GLUES and ADHESIVES
Application to Model Building
By: Eugene L. Larson

Former NRG Chairman of the Board of Directors

Copyright (c), August 1, 1999

Updated December 1999
Note: The NRG is liberal in releasing copyrighted material for various purposes when requested, however, be aware that this article contains material from another publication, included here with permission.

Very seldom have the technical aspects of the glues and adhesives been put together with the practical applications. There have been some very broad, incomplete, inaccurate and quite uninformative articles on glues and adhesives appearing lately in various publications. This presentation is meant to provide an overview on the types available, their properties, and their application to ship model building. The sources of information, as mentioned within the article and listed in the references at the end, are mainly from reputable magazines and professional workers, with as little of my personal influence as possible, except in areas where there is a lack of details. I urge the model building community to contact me with updates and suggested changes.

SOME BASIC CONSIDERATIONS

Fit of the Joint
Always make as close a fit as possible when joining materials. Do not expect glues to work properly in gaps. The maximum strength of most glues occurs when the fit is close and a minimum amount of glue is used. Also do not expect glue to fill the gaps. The surfaces must be clean and free of debris.

Securing
I always try to provide a mechanical form of securing materials and fittings since I do not want to depend on the glue alone. Small pegs of metal rod, cut off brads or small wood dowels inserted, for example, in the bottom of wood stanchions, deck structures, gun carriages, and general deck fittings, will insure a firm mounting. Then only a small amount of glue is needed, and this helps prevent those ugly smears that are difficult to clean off. A light bump on a glued fitting can send it adrift. A pegged and glued fitting will usually stay fixed. If one is knocked off the builder will have to learn to be more careful!
A remark by Dana Wegner, Curator of models for the U.S. Navy, "We really liked your section on mechanical fastenings used to supplement glue joints (or vice versa.) It's an excellent practice."

Application
It is usually not advisable to apply glues from the furnished bottle or container due to the lack of control of the quantity. The only time this is successful is when large pieces are being bonded and the glue needs to be applied in larger quantities. The best method for applying glues to small parts is with a special applicator. There are some commercial applicators made especially for model work, but the homemade types are just as good. Small dowels, toothpicks, thin wire, and wire with a small applicator loop in the end are very adequate. I generally use toothpicks to mix epoxy, and then use the same toothpick to apply it. Note: mixing epoxy on discarded margarine tub covers is very convenient. The few times that I use super glues I apply them with a drop on the end of a thin wire, or I use the slotted end of a fine sewing needle with the end ground off so it looks like a two tine fork. Clean the set super glue off the applicator frequently by cleaning with acetone. Some recommend removing the residue with a flame, but be aware that the resultant fumes are extremely poisonous and will make you ill. The fumes can cause severe respiratory problems and possible loss of consciousness.(3)

The Bond
William Tandy Young in Fine Woodworking, January/February 1999, (1) states that almost all glues will provide a bond stronger than the wood they join, except for wheat or rice paste, hot-melt glue and contact cement. Also, the moisture content of the glue should be considered for the specific project. High moisture in the glue can effect the outcome of applying thin woods such as veneers. Most of the natural and nonreactive glues above have a high moisture content.

The bond should be material to material with nothing in between such as a painted surface. Attaching a fitting to a painted wooden hull, for example, results in attaching the fitting to paint, and the bond is fragile and no stronger than the weakest bond of the fitting to the paint, the paint to the primer, or the primer to the wood

Fine Woodworking magazine, September/October 1992, (7) explains how glues interact with the chemical components of wood, which is a complex mixture of organic chemicals and water. Approximately ninety-five percent of wood is the structural matrix which provides strength, rigidity and elasticity. These components are the cellulose, lignin and hemicellulose. Five percent is resins, oils, tannins, gums, coloring and sugars.
When glue is applied it is absorbed into the wood and combines with the structural fibers. "The glue's polymer molecules then come together, surround the structural fibers and harden, mechanically interlocking the fibers. Thermosetting glues such as epoxy, urea formaldehyde and resorcinol, cure by a chemical reaction. Thermoplastic glues such as white and yellow glue, cure by evaporation." When cured the glue provides the bond to hold the pieces of wood together.

Metal to metal
Whenever possible join metals by soldering or brazing. Do not use solders containing lead due to their deterioration over time. When soldering or brazing is not possible then the next choice is epoxies. Super glues are not recommended - see comments below.

Color, absorption and smearing
The color of glues is important. White glues such as Elmer's dry clear with a slight shine. This property is a great advantage where the glue line or glue area might be seen. The stronger yellow glues such as the Titebond products and Elmer's Carpenter glue dry yellow, however, the glue line should not be a problem if the fit of the materials is close, as dictated by good skills and by the glue manufacturers.
The viscosity of the glues and the porosity of the materials being joined determine the amount of absorption of the glue. The thin super glues are not recommended for wood because of the absorption problem. There usually is not enough glue left in the joint area to provide an adequate bond, and more and more glue is applied in an attempt the secure a bond. The thicker super glues avoid this problem somewhat. The higher viscosity PVA glues do not present a problem as they generally remain close to the bond area. In some cases a thin glue is desired. If the white glues such as Elmer's are thinned with water they can be absorption into rigging knots and seizings. When dry the clear glue provides enough strength to hold the rigging in place. Other than this application it is not recommended to dilute glues very much as their strength will be compromised.
Manufacturers recommend the application of only enough glue to fill the joint, with perhaps just a little squeeze out. This is very difficult to judge, but well worth the effort. When, for example, two pieces of wood are joined with Titebond II (one of my glues of choice), and squeeze out occurs, the first reaction is to wipe off the joint. Then a smear occurs that covers a relatively large area of the surface. The best advice is to let the glue set until rubbery, not rock hard, and scrape the joint with a knife or razor blade. There will still be some glue in the wood pores immediately next to the joint, but not as bad as a smear.
The purpose of this discussion is directed at the finishing of the model. None of this matters if the model will be painted, however, a natural finish with stain, tung oil or varnish will look terrible since the smear areas have sealed the wood and will not permit the finish material to cover evenly. The result is the area must either be scraped and sanded enough to remove the surface glue, or you will have to give up on the natural wood finish and resort to painting. Most epoxies (the other glue of choice, especially for radio control models) cure clear and if the wood surface is not to be stained, usually a flat varnish closely matches the epoxy, and a smear area cannot be seen.

Clamping
In most applications clamps should be used when joining materials. They hold the parts in the proper position and tight together which makes the bond stronger. The clamping time will vary depending on the glue being used. Super glues set and cure within seconds while some PVA glues grab quickly but set in one hour and cure in twenty four hours. See the separate shop note on clamps
A remark by Dana Wegner, Curator of models for the U.S. Navy, "Mike Condon (in the model shop) points out that it is possible to make a glue joint too tight, and therefore weak. It is possible to have two very smooth pieces of wood and clamp them too hard and force out the glue between. This condition can easily occur when fitting pegs into too tight holes. Sometimes you have to consciously avoid making a glue joint too tight."

Shaping to relieve stress
In model work where the surface areas to be joined are quite small it is always best to not rely on the glue to hold pieces under stress in place, such as encountered with hull planking. The wood should be shaped to nearly the final configuration before applying glue. This shaping can easily be accomplished by heating the wood and bending it to the desired contour. This heating can be accomplished in many ways, and models builders are ingenious in finding all of them. A soldering iron or a specially adapted commercial plank bender resembling a soldering iron works well. Anything that will apply heat to the wood to permit a softening of the fibers will work. A little moisture on the wood sometimes helps in the heat transfer. The wood is heated and bent off the model, test fitted, and heated again if necessary.

Longevity
Where possible, the longevity of the glues is identified below. As a special note however, it is informative to mention here the "SPECIFICATIONS FOR CONSTRUCTION OF EXHIBITION MODELS OF U.S. NAVAL VESSELS" published with permission of the Curator of Models, U.S. Navy on the NRG web site at http://www.Naut-Res-Guild.org/usn-spec.html. It is stated:
As part of the permanent collection of the Department of the Navy, it is reasonable to expect a new ship model to last one hundred years before deterioration is visible. Therefore, resistance of models and parts to the actions of temperature, humidity, and light is essential. Extreme care must be given to select materials which are known to be compatible and will not, in time, interact chemically.
Although only a few materials are prohibited in "Specifications for Construction of Exhibition Models of U.S Naval Vessels," some recently developed model-building materials and techniques should be avoided until sufficient time has passed to properly evaluate their longevity. Though some of these recently introduced materials may ultimately test superior to more traditional techniques, substances of unproven longevity should not be employed in models built under these specifications. It is advised that fiberglass resins, styrene, expanding foams, casting resins, and cyanoacrylate glues be avoided when other materials can possibly be used. (The bold emphasis is made for this article.)

Water Resistance of Glues
Further, attention should be given to the water resistance properties of the glue you intend to use. This is usually a consideration for models that will be placed in the water. However, in most cases the hull will be coated with a water proof material, and the choice of glue becomes mute. The water resistance properties of glues as discussed in Fine Woodworking Magazine generally line up as follows: (1)

Marine epoxies
waterproof, good for coating and sealant
Resorcinol
waterproof
Polyurethane & urea
extremely resistant - extended immersion
Type II PVA
resistant - short exposure
PVA & others
do not use for high moisture applications

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Some Comments on Various Glues by Model Builders

Christopher Morrison, long time NRG member, made the following comments in his article on Catboats and his model of Pauline.
Small brass stock was held to a master in order to file to shape. "Shellac is nicer than cyanoacrylate for such work because it is so quick and easy to undo with heat. One stick of furniture repair shellac will provide several centuries worth of adhesive."
"The 3-inch block shells used in the rig were built up of pearwood cheeks grooved for a strop and pearwood swallows. These were glued together with the tiniest dabs of epoxy. The trick was not filling the strop groove, since it is only a few thousandths deep and could never be cleaned out afterwards. Epoxy is ideal for this because it does not evaporate, and therefore does not skin over when used in minute quantities, as water-based glues like Elmer's do. Consequently, mating pieces are properly wetted with glue upon assembly, reliably producing sound joints." (NRJ 39-4)

Erik A. R. Ronnberg, Jr., former Editor of the Nautical Research Journal and highly acclaimed professional model builder and researcher had the following observations in his series of articles on "Steam Trawlers Come to the Boston Fishing Fleet", in which he describes the construction of the model of Surf of Boston.
"Cyanoacrylate glue was spotted at a given strake's ends and middle, and yellow carpenter's resin glue was carefully spread between the spots without touching them. The cyanoacrylate acted only as an instant clamp to hold the strake firmly in place while the carpenter's glue set." (NRJ 40-1)
"The choice of glues for this work was also important for the model's longevity. I have used Weldwood powdered resin glue for hull glue-up since the late 1960s. When lifts are snugly clamped so there are no gaps or slack seams in the glue joints, the bond is very durable and the glue is compatible with most finishing methods. This is the only part of the model where I use this glue; there are few other situations which allow the careful clamping which is absolutely necessary to get a strong bond. Close contact between the wood fibers of the joining surfaces is essential; only the smallest amount of glue is needed to cement these fibers together. If the glue forms a solid mass which separates the joining surfaces, a weak, very brittle bond results and it doesn't take much of a shock, such as from dropping, to cause the glue to shatter like glass.
"For the vast majority of wood-to-wood joints, I use Elmer's yellow carpenter's glue or its equivalent. This is the glue I used to apply the basswood "out" strakes to the model, as its flexibility matches that of the materials it is joining. In only a few cases, where great strength or rigidity in a very small gluing surface are needed, will I use epoxy glues on wood. They are extremely strong and tough, but very rigid and unable to move with wood. I once glued up a large hull of obeche lifts (too soft - never again!) using epoxy resin. After a couple of years, the lifts had shrunk, but the glue did not; every glue seam stood out!" (NRJ 40-1)
In applying copper wire to the hull to simulate rivets (3/8"=1'): "The wire was roughened by drawing it through sandpaper, the tip dipped in flat acrylic varnish, and pressed into a hole. Acrylic varnish makes an excellent "glue" for this purpose and has the advantage of being compatible with the gesso and overlying finish coats of acrylic paint." (NRJ 40-1)
In summary: "Wooden parts were glued to wood with yellow carpenter's glue; metal-to-wood and metal-to-metal joints were glued with epoxy. In some cases, mechanical fasteners were used." (NRJ 40-2)

A remark by Dana Wegner, Curator of models for the U.S. Navy, "Safety -- The David Taylor Model Basin used to use Weldwood powdered glue (mentioned by Erik A. R. Ronnberg, Jr) exclusively and extensively for the tow tank models. We always used it for gluing up lifts. If carefully mixed it was good stuff. Several years ago the product was banned for our use by the Navy because the dry powder was found to contain formaldehyde and is a carcinogen."

Dr. John M. Bobbitt, award winner at The Mariners' Museum, NRG essay winner, and long time NRG member states in his article on "Wave, A Chesapeake Bay Pungy", "I do not trust Cyanoacrylate glues and use them only rarely to join very small parts under no torsional stress." (NRJ 40-3)

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Quick Reference on What to Use
For a quick layman's listing of what glue to use for various applications go the web site: http://www.thistothat.com/.

CATEGORIES AND TYPES

William Tandy Young in Fine Woodworking (1) defines "glue" as being based on polymers from natural sources (starch and protein such as rice or cattle hide). These natural glues are generally reversible with the application of water, a property desired by some archivists. "Adhesives" are based on chemically synthesized polymers (PVA resins) and usually cannot be reversed. There is generally no distinction made between adhesive and glue in casual use.
There are three major categories and many types of glues and adhesives (1) with potential for common use by ship modelers, plus an "other" category added by the author. These are discussed in detail within this article:
NATURAL GLUES
NONREACTIVE SYNTHETIC GLUES
REACTIVE SYNTHETIC GLUES
OTHER (added by author)

RATING GLUES
The August 1999 issue of Consumer Reports (2) rates "household adhesives" in a very brief two page article, but they have a direct application to model building. Consumer Reports does not release copyright on their published materials, therefore, the results cannot be repeated here. However, an issue can usually be found in a local library, or for a fee can be accessed on their web site.

PROPERTIES OF GLUES AND ADHESIVES

NATURAL GLUES

Rice and Wheat Pastes
Bond: porous materials, i.e. paper, cloth & leather to wood.
Strength: do not use to bond wood
Longevity: poor unless preservative is added to inhibit fungal attack

Fish Glue
Bond: wood to wood, natural materials, i.e. cloth, metal & bone to wood, grain filler
Strength: light duty bonding
Longevity: becomes brittle with age

Hide Glue - an old traditional glue
Bond: most materials to wood, edge and face gluing, & veneering
Strength excellent, but avoid thick layers which become brittle
Longevity: may become brittle with age

Casein Glue (made from milk) - an old traditional glue
Bond: oily woods, veneering. Thick glue lines. Some gap filling
Strength: excellent & creep resistant
Longevity: poor unless preservative is added to inhibit fungal attack

NONREACTIVE SYNTHETIC GLUES

Ethylene Vinyl Acetate Glue (EVA)
Bond: mainly woodworking for cross grain wood with expected movement
Strength: little rigidity and creep resistance
Longevity: affected by heat & moisture
Cleanup: water

Polyvinyl Acetate Glue (PVA) white and yellow glues. (The term Aliphatic resin is meaningless (1))
Types:
White - low grade craft/hobby/school, paper and fabric
Yellow - high grade professional & industrial
Bond: - edge & face wood gluing, plastic laminates
Strength:
White - adequate but low rigidity & creep resistance. Highly flexible, but rubbery composition clogs sandpaper.
- Will not take any strain so use it only for non-stress and non-load bearing parts unless fasteners are also used.
Yellow - higher strength, rigidity, durability & creep resistance - they are comparable to epoxies, but fasteners are still desirable.
Longevity:
White - low resistance to heat & moisture, and is shock resistant. Inside use only. Freezing will ruin the glue.
Yellow - High resistance & shock resistant
Both will degrade in high UV light
Setting time: short to medium grab time, but should be clamped for maximum strength.

Note: PVA glues will adhere more than just wood, however, the bond will not be as strong. The white (clear dry) glues can be used on transparent plastic items such as canopies, windows, portholes, etc. without evidence. (3)

A remark by Dana Wegner, Curator of models for the U.S. Navy, "In concert with my report on lead rot, I would ask that model builders recall that PVA glue and some brands of silicon sealant release acetic acid which can be harmful to lead fittings in a stagnant environment."
See the NRG web site at: http://www.Naut-Res-Guild.org/lead2.html

Contact Cement (recommend water based products due to toxicity)
Bond: laminates & veneers
Strength: no permanent structural strength, rigidity or creep resistance
Longevity: poor moisture & solvent resistance, good heat resistance
Note by Ben Lankford (Former NRG Director and Treasurer) in NRJ 14-3, "Contact Cement is good for copper bottoms and also for sticking deck houses down on decks when you do not want glue squirting out on the deck. Be careful to line up first or you will wind up with a crooked deck."
A remark by Dana Wegner, Curator of models for the U.S. Navy, "Ben's (recommended) preference for contact cement for copper plating would suggest that he has never had to reattach those little plates when they flutter off the model in five or ten years. In our experience, except for ease in application, contact cement is a terrible choice for copper hull plating."
As you know, you need a plan for applying contact cement in advance of applying the copper. You can't work too much in advance, nor can you be too slow. The smell can get you too. We have found that contact cement seems to dry up between five and ten years after application. The actual time probably depends on the brand, the technique, and the environment.
Author: "then what do you use for hull plates?"
Dana Wegner: "We use 3M adhesive film for copper. (See below)"

Hot-Melt Glue
Bond: edge banding sheets & for jigs and temporary projects
Strength: very little
Longevity: moisture resistant but no heat or solvent resistance
Note: The woodworkers white stick hot melt glue can be used on bulkhead models (3)

REACTIVE SYNTHETIC GLUES

Urea Resin Glue
Bond: exterior wood joints, laminating, veneering
Strength: very strong, rigid & creep resistant, especially two part products
Longevity: may become brittle with age, especially lower grades
Setting time: quite long
Products: Cascamite, Aerolite

Resorcinol
Bond: face & end wood bonding, veneers & laminations
Strength: very strong, rigid & creep resistant
Longevity: solvent & heat resistant
Note: Highly visible joint due to red color
Note by Ben Lankford (Former NRG Director and Treasurer) in NRJ 14-3, "For gluing up lifts of models try Resorcinol instead of Weldwood Plastic Resin glue. Resorcinol comes in two parts which, when mixed together, sets with an excellent bond and is completely waterproof; it will not shrink, will not deteriorate in the can (Weldwood does), is red in color and is available from any hardware store."
A remark by Dana Wegner, Curator of models for the U.S. Navy, "Ben Lankford's (recommendation on) Resorcinol glue is, indeed, the best waterproof glue available. Those considering it should know that dry (cured) resorcinol is usually considerably harder than the wood it adheres. It is difficult to carve and sand lift models glued with resorcinol because the glue joints are harder than the surrounding wood, usually resulting in raised glue lines. Also hard Resorcinol is tough on edged tools and dry glue fragments can damage your eyes."

Epoxy
Bond: wood, veneers, laminations, metal parts to each other and to wood.
Strength: excellent but relatively low heat resistance, even sanding heat. I prefer Devcon epoxy: the plastic steel, the short 5 minute, and the longer setting two ton brands.
Longevity: excellent.

Note by author: Epoxy is a good sealer for porous woods, and for waterproofing if marine epoxy is used. If the epoxy to be used as a "sanding sealer" is too thick it can be thinned to the desired consistency with denatured alcohol. (Too much thinning might effect the bond to the wood and might induce cracking over time.)
Epoxies come in various cure times, and it is generally accepted that the longer the cure time the stronger and less brittle the bond. They also are available various consistencies ranging from a thin liquid to a thick putty. The thick epoxies are excellent for embedding propeller shafts and rudder tubes on radio control models. I place car body fillers in the epoxy category and recommend their use for many applications.
They seem to be the strongest of the adhesives available. Color can be added to them for fiber glass work, and they have advantages in solving many structural bonding problems. They can be used to "glaze port holes.(3) They can also be used as fillers and for sealing wood (vs sanding sealer).
Note by Ben Lankford (Former NRG Director and Treasurer) in NRJ 14-3, "Epoxy comes in two types, both useful. The first is the two tube type, amber color when mixed. This is good for small parts, both wood and metal, that require good strength. The second is the thick grey kind which comes in large containers and is excellent as a filler and provides a good glue bond at the same time, something you can not get with regular wood filler. Though it sets harder than most woods, it sands well."

Polyurethane
Bond: wood, laminations, veneers, metal. Tight fit and clamping required, however, these do expand on curing and fill in slight gaps quite well and they are sand able (Lloyd Warner, NRG Secretary).
Strength: good strength with creep resistance & rigidity
Longevity: not available

Cyanoacrylate Instant glues (Super Glues)
Bond: rapid bonds of small pieces of wood and other materials. Not for large pieces
Strength: Very strong & rigid. Fair durability on small surfaces. Good in tension, poor in shear
Longevity: Good moisture & heat resistance. Poor solvent & shock resistance. Will yellow & may degrade in UV light

Cyanoacrylates are available in various consistencies ranging from a thin liquid for close fitting low porous materials with on gap filling capability medium viscosity thicker "gels" for porous materials and some gap filling capability.
They are also available for purposes ranging from wood, plastic, metal, general purposes, etc. Some can attack various coatings and materials.(3) It is advisable to always test the compatibility before using on the project.

Do not use CA glue in projects that come in contact with water.(4)

Note by author: This glue is not recommended for model work by certain builders. It has been suspected to have a chemical reaction with copper and brass. In a Shop Note by Peter E. Demarest, he states in part, "Every (brass) hook on the model that was in touch with the cyanoacrylate was in some stage of failure, and only those hooks were affected" (Nautical Research Journal, Volume 40, Issue 2, June 1995)(5).

Dana Wegner was asked what glues are on hand in the U.S. Navy Model Shop. He replied, "white PVA and cyano". However, Michael Condon, Ship Model Conservator in the Model Shop explains, "In response to Gene's question about why we have CA in the shop if we don't allow it in our specifications. We use this adhesive out of necessity, on occasion, when speed and work volume become considerations. Many times we are in a situation where we are forced to fast-track a project or perform work in the field under time constraints. We consider our use of CA to be prudent because we have had extensive experience with it and are familiar with its shortcomings. So, we only use it in situations where we are confident in its abilities. We avoid reliance on its structural strength, especially over the long haul, by extensive use of fasteners and by relieving strain at the attachment site. Typically, we will only use CA for the formation of fillets or in an attempt to add girth and dimension to a detail. CA is somewhat hygroscopic, so a vapor barrier is very important to its longevity. Climate controls and a lack of exposure to organic solvents is critical to this material's success. Furthermore, when we use CA we know its exact location on the model so we can closely monitor it. We discourage the use of CA on contract models because we cannot control its exact application. We choose to make our lives simple and "just say no."

A word of warning by Charles O. McDonald, former Editor of the Nautical Research Journal, in Volume 33, Number 2, June 1988, "Some topmast futtock shrouds I had worked on just before abandoning the project (to become Editor) and had secured with cyano-acrylate to prevent their distorting the lower shrouds when their lanyards were rove became entirely crystallized despite being linen cord. When I resumed work, they broke like thread made of glass. DON'T use CA anywhere around rigging! It is handy for many things, but not that!"

In addition, its longevity has not been proven conclusively, and to my knowledge no conservators recommend its use. When used in rigging ships the glue makes the lines very rigid and susceptible to breakage. For porous woods such as basswood (lime), mahogany, etc., it must soak in and build up sufficient material to create a bonding surface. An initial application, which is allowed to set, helps to seal the pores, and the next application will hold. However, the super glues make the wood brittle. The absorption effect inhibits the use of stains and natural finishes on wood much more that the other adhesives that only fill the joints.
However, the super glues have been very popular with the resin kit builders who concentrate on 1/700 and 1/350 warship models. The glue is especially useful in bonding the very fine photo etched brass fittings including the ship's railings. There apparently has not been a problem identified to date with the use of the instant glues on the models. Time will have to be the judge.

CA comments by former NRG Director and long time member John Fryant (Riverboats & Tug boats plans service)
"Its too bad the Consumer Reports article didn't test some of the leading hobby CA glues, such as Zap, made by Pacer Industries, or Insta Cure, made by Bob Smith Industries. I've used both these brands extensively with very satisfactory results.
"I have found that very good metal to metal joints can be made with CA providing that the metal pieces are absolutely clean. I usually sand the joining surfaces with 220 grit paper, then wipe them clean with a tissue or cloth.
"A far as using CA as a filler, plastic modelers do this all the time. I constantly read kit reviews in FSM where the author uses and recommends medium or thick CA as a filler around poorly fitting parts. I doubt it would be good for this purpose on a wood joint, as the cured CA is harder than the surrounding wood, therefore making sanding difficult.
"As for the permanence of CA, that's where I disagree with most critics. I've been using CA for about 21 years now on both personal and contract models. I have yet to hear of one of my museum models falling apart. Also I've used CA to glue paddlewheel parts together - hundreds of little plastic bolt heads and wire stirrup bolts, all glued to plywood arms and bucket planks. These are working paddlewheels for R/C models and are subject to constant immersion and drying off, changes in temperature and humidity, etc. One of these wheels has been in service for about ten years and nothing has fallen off ( yet!) Of course, all of these parts are painted after assembly, which waterproofs the glue joints somewhat.
"Of course, time is the only thing that will tell the tale both for acrylic paints and CA glues, which become an acrylic plastic when they cure. None of us will be around 500 years from now to see if those paintings and models are still intact. I guess when that time comes we will be either praised or condemned for using acrylic products."

Long time NRG member Phil Krol states:
"Cyanoacrylate glues will continue to be used by modelers in spite of their shortcomings. Two brands absent from the test list commonly found in hobby shops are ZAP from Pacer Technology and Bob Smith, who puts the hobby shop label on the bottle. My personal preference is Zap. The Bob Smith formula seems to have more surface tension, and doesn't flow into a joint as readily. You may want to consider mentioning the use of accelerator for CA and also debonder.
"Another application technique for CA is putting a capillary micro dropper on the bottle spout. These will dispense micro drops directly from the bottle in a controlled fashion, one micro drop at a time. I used to be able to buy them on a card, 6 for $.50, but when my supply was running low, I found they were no longer available. I now make my own from Teflon tubing by drawing them out in a flame just enough to soften the Teflon, but not burn it. Perhaps this may be more than most modelers would want to get into."

Dave Judy, an outstanding warship model builder in the Washington Ship Model Society states:
" I prefer the CA glues but also use epoxy in some applications. The Enterprise carrier was constructed entirely using CA, and the hull was 6 pieces doweled together, no cracks even when subjected to extreme (from room temp to car in winter) temp changes. Being of mixed media this was a concern! As for longevity only time will tell as you have said."

Also, please see the comments under "Longevity" at the beginning of this article.

OTHER (added by author)

Adhesive Film
This is the 3M type adhesive strips that has a peal-off backing on each side. It is adhesive only, without a plastic carrier such as Scotch tape has.
Bond: for most any smooth surface contact. Especially good for copper hull plating.
Strength: excellent bond if there is a close contact made.
Longevity: lasts much longer than contact cement. It has been used for many years.

Dana Wegner says, "We use 3M adhesive film for copper. We have considered using the film in a few cases where we might use glue. But we have not tried it yet. Some likely areas would be like joining small superstructure elements to decks, attaching gun mounts or gun tubs to decks, etc. Before using the film for copper, we had good luck with old PVA too. (Believe it or not, PVA has some metal to metal bonding capability.)"

Joe McCleary has used the adhesive tape and provides the following source:

The product is 3M Hi Performance D/C Polyester Tape with Poly Coated Liner; Product number 9500PC. It comes in rolls 3/4 inch wide by 36 feet. It is available from 3M Bonding Systems Division, St Paul, MN 55144 (tel 1-800-362-3550). The only catch is, 3M will not sell direct to anyone who wants to buy less than a case, which contains 24 rolls (we could supply the whole NRG and then some).

I did locate a retailer named Gard Distributing Co. who will sell by the roll. The price is $12.64 per roll plus shipping. Compared to the price that 3M quoted, Gard's price is reasonable. The address is:

Gard Distributing Co.

6981 NW 42 Street

Miami, FL 33166

Tel 305-592-6920

I dealt with Gard by phone and ordered using a credit card with no problem. They shipped via UPS. I had located several other distributors, some thru 3M and some by other means and none but Gard would deal in less than case lots. I suspect that they did not stock the tape and would order from 3M to fill a case lot order. Gard seems to keep the stuff on hand.

Although 3M does not want to retail this stuff, if you call them at the above 800 number they will send you a sample roll containing 3 feet of the tape to try out. I ordered a sample roll to try out before buying a full roll (actually I bought two rolls - a lifetime supply) and found that it is easy to work with and does a good job.

Plastic (polystyrene) glues
Bond: mainly plastic to plastic. The plastic is partially dissolved by the glue and the bond becomes permanent - similar to a weld
Strength: if properly made the bond is as strong as the original plastic, however, certain glues of this type contain chemicals that remain in the joint and can cause brittleness with time.
Longevity: no known effects from aging
Note: There are generally two types of plastic glues. The type available in tubes contain a plastic base and a solvent. When set the solvent has evaporated the base remains. The liquid cements come in a bottle and contain only the solvent. Many model builders recommend the second type.(3)

Fiberglass resins - both epoxy and polyester
Bond: fiberglass molded parts to each other and to wood but bonded surfaces must be sanded. Good sealer for porous woods and for waterproofing. Can be used in place of sanding sealers.
Strength: high strength if mixed properly but less than if fiberglass were imbedded in the resin.
Longevity: brittle but no known aging effects.

Solvent glues the basic "ageless" model building glues.
Bond: plastic, wood, ceramic
Strength: not too good, but flexible
Longevity: Not available, but have been used for many years. Shrinkage during the cure process may be a problem
Caution: notable for the toxic and flammable fumes they produce. Use ventilation
A remark by Dana Wegner, Curator of models for the U.S. Navy, "Longevity. Ambroid glue, similar to old "Duco" cement, is celluloid based. Dry or wet it is flammable and potentially explosive. It usually has poor longevity. A dinosaur from the age of "airplane glue."
Note by Ben Lankford (Former NRG Director and Treasurer) in NRJ 14-3, "Ambroid is good only for sticking two lacquered parts together, even though many ship model builders swear by it and use it for many tasks. However, I still think it should stay with the model airplane builder."

Goo
Comments by former NRG Director and long time member John Fryant (Riverboats & Tug boats plans service)
"Goo is marketed by Walthers and aimed mostly at the model RR market. The labeling on the tube proclaims this to be 'a rubber based adhesive'; beyond that I don't know what it's composition is. It has been around for at least 45 years and is one of the best adhesives for joining dissimilar materials.- brass to wood, for example. Goo is very much like Goodyear Pli-O-Bond, which I haven't seen for awhile.
"One of the best techniques for joining metal to wood with Goo is to heat the metal part after the pieces are joined. When you see the Goo bubble out from the joint remove the heat . After it cools you will never be able to separate the pieces!"
A remark by Dana Wegner, Curator of models for the U.S. Navy, "John Fryant's (recommendation on) Goo was always one of our favorite "temporary" glues (it doesn't last very long) but it was also banned by our safety office because of one of the solvents in it. I cannot recall which one gave them a problem. It was a long time ago."

"Varnishes"
Although not conventional, for small parts and special applications clear acrylic (flat or gloss coat, Future Floor Wax/Johnson's Kleer/etc.) or lacquer/enamel based clear coats can be used. The acrylics have the advantage of drying quickly and quite flat (especially Future).

Silicon bath sealant (caulking)
This material can be used in radio control boat applications where operating parts need to be fixed inside the model but future removal may be necessary, such as for ballast, radios, and motors.(3)

Special recognition and thanks -
to the following persons who made contributions to this article and who provided suggestions and changes:

Dana Wegner, Curator of Models, U.S. Navy, and his associates: Colan Ratliff and Mike Condon, David Taylor Model Basin, Carderock, Maryland
John Fryant, A former Director of the Nautical Research Guild, Owner, Plans Service, 6508 Dorset Drive, Alexandria, Va. 22310-3018, Riverboats, tugs, barges and ferries, E-mail to: Jnoboat@aol.com
Lloyd Warner, Nautical Research Guild Secretary, Owner, Warner Woods West, P.O. Box 100, Ivins, UT 84738, Milled specialty woods, blocks, & cases, Laid up linen line, E-mail to: warwoods@xmission.com
Phil Krol
Dave Judy

More detail can be found in the following sources, most referenced above:

REFERENCES
1. Fine Woodworking magazine, January/February 1999, "A working Guide to Glues" by William Tandy Young. Copyright release is greatly appreciated.

2. Consumer Reports, August 1999, "Stuck on Glues".

3. Marine Modeling International, "Adhesives for Marine Modeling", by Ian Williams, November 1998, Traplet House, Severn Drive, Upton-upon-Severn, Worcestershire WR8 0JL, England.

4. Wood Magazine, "Easy Reference Guide to Woodworking Glues", August 1998, Better Homes and Gardens, 1716 Locust Street, Des Moines, IA 50309-3023

5. Wood Magazine, "Ask Wood", October 1999. ibid.

6. Nautical Research Journal, published by the Nautical Research Guild, various issues.

7. Fine Woodworking magazine, September/October 1992, "Adhesives for Woodworking" by Chris Minick.

Copyright (c), August 1, 1999
Note: The NRG is liberal in releasing copyrighted material for various purposes when requested, however, be aware that this article contains material from another publication, included here with permission.