From: Don_Schmitz@transarc.com
Date: Mon Aug  3, 1998


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Part 4

Part 4 ** General how-to questions ** ** This sections covers frequently asked questions regarding construction ** techniques that can be answered in a few paragraphs. Questions with ** longer answers have their own FAQ section. Most of these questions ** are fairly general, although some very specific questions are asked so ** frequently I've included them here too. [Q] How do I remove "chrome" from plated parts? [Q] How do I remove paint from a model? [A] schmitz@transarc.com (Don Schmitz 8/95) The "chrome" plating on model parts is extremely fragile, and most hobby paints aren't much tougher. There are hobby specific paint removers available at hobby shops, Easy-Lift-Off made by Polly S has been recommended, but many household cleaners will also remove paint and/or chrome. Find a plastic container with a lid and soak or scrub the part or complete model in/with one of the following, listed in roughly increasing order of chemical nastiness: Castrol Super Clean (hand cleaner ? - buy at auto stores), Fantastic, Formula 409, Pinesol (not lemon scented), chlorine bleach (works good on chrome, maybe not paint), using a toothbrush to scrub with Comet cleanser (for chrome, not paint), EZ-Off oven cleaner, common dot3 brake fluid (more toxic - not good to wash down the drain - but good for long dry paint). The time to soak varies with harshness of the chemical, from a few minutes to a few days. Chrome plating should just disappear, you'll likely have to scrub the paint off with an old toothbrush, especially from the nooks and crannies. Some cleaners are reported to etch or embrittle plastic, so keep the exposure brief and flush with water afterwards. A downside to the harsher, faster acting chemicals is that they tend to remove putty as well. One thing *not* to use is standard methyl-ethyl ketone based paint removers - this stuff will disolve styrene very quickly. Lemon scented Pinesol has also been reported to soften plastic. Finally, the nastier of these cleaners - especially the EZ-Off and bleach - can cause burns to the skin, eyes and nose, and who knows what else. Use common sense and lots of ventilation (common sense includes wearing safety goggles, rubber gloves, and a respirator when using this sort of stuff). [A] schmitz@transarc.com (Don Schmitz 10/97) Since I wrote the previous answer, several new [I think citrus-based] products have appeared that have been recommended by various rms participants. Word is they work as well or better than the traditional cleaner-based products and are much less toxic and enviornmentally unfriendly. One product - named "Strip-A-Kit" - is marketed specifically for model use and is sold by rms "regular" Rick Fluke. For more info and ordering information check out his web page at: www.montana.com/people/home2/arl3845/www/hangar1.html [Q] How can I get a chrome finish onto a part? [A] schmitz@transarc.com (Don Schmitz 8/95) The "chrome" finish on model parts is really vacuum deposited aluminum, and requires specialized (read expensive) equipment to do - it is not a do-it-yourself sort of project. There are aftermarket companies that do this sort of work - you send them carefully polished plastic parts and they chrome plate them. It is somewhat expensive - order $20 for a handful of parts. Look for ads for these places in the modeling magazines. "Chrome Tech USA" is one that comes to mind. If you are trully obsessive, the best chrome finishes are achieved by casting/fabricating the parts in brass and having them nickle plated by a bumper shop or jewler, or casting directly in silver. Needless to say, this is beyond the scope of this FAQ. [Q] If I'm not that obsessive, what paint is closest to chrome? [A] schmitz@transarc.com (Don Schmitz 9/96) If you don't want the hassle of sending the parts to a plating shop, here are two alternatives: 1. Rustoleum brand "Chrome" spray paint, #7718, available in hardware and department stores (in the US at least). May attack styrene slightly, so use an automotive type primer underneath. 2. Prepare the surface as for a natural metal finish, paint gloss white and then buff on SNJ polishing powder (see section 8 for info on natural metal finishes, and section 9 for contact info for SNJ products. [Q] How can I remove decals without screwing up the paint? [A] kmartin512@aol.com (Keven Martin) Try brushing on some decal solvent, letting it sit for a few minutes,then burnish some real tacky masking tape over it. Then just peel away. It may take a few tries, but will not ruin paint. [Q] How do I make my own dry transfers? [A] schmitz@transarc.com (Don Schmitz 8/95) Dry transfers - graphics using "rub on letter" technology, are much easier to make (and afford) than custom decals. This is a summary of an article that appeared in the December '94 issue (#94) of "Scale Auto Enthusiast", written by Pat Covert. The process they describe is to produce original black on white artwork using a good quality printer/copier. You produce a positive - ie. the black is the part you want to become the marking. The print shop will expect a true size image to fill a 7 x 9 inch sheet. The article suggests drawing/producing the artwork at 2 or 3 times actual size, and then reducing it with a good quality copier to smooth out minor glitches (eg. quantization staircases). Mount the on-paper atwork on a sheet of white posterboard for strength, using 3M spray adhesive. Leave 3/8ths of an inch between items on the sheet, and a similar border around the edge of the sheet. Just about any color ink can be matched, but you pay more if it is a custom mix. Typical costs were given as $8 to produce a negative (you should be able to have this done locally by a type-setting shop if you find a service that prefers to produce the transfers directly from a negative rather than on-paper artwork), and $25 per sheet. It didn't mention if there was a quantity break for producing more than 1 sheet at the same time, but most modelers have a hard time filling up 1 sheet. The claim was most any commercial print shop can make these transfers (they are used by architects to produce repetitive details on drawings of buildings, and by advertising shops to mock-up new product packaging). The author did give the name and address of one shop he has used that will do mailorder work: Lithoplate and Negative, Inc 2429 3rd Avenue South Birmingham, AL 35233 205-251-7291 Another source, dedicated to doing modeling work and highly recommeded by many r.m.s participants, is Archer Fine Transfers, owned and run by Woody Vondracek, who often posts here on r.m.s (email address is transferman@mindspring.com): The following text was provided by Mr. Vondracek: My company, Archer Fine Transfers, has been producing custom made Dry Transfers for model builders for over six years and is the only Dry Transfer company to create chemistries specifically designed for scale model builders. I also supply instructions and inexpensive materials to convert dry transfers into water-slide decals as well as producing a line of three dimensional Dry Transfers that replace or add rivets, etc. lost during sanding or to vac-form / resin kits. I do all of my work in my newly constructed workshop and turn around time is very reasonable. My rates are fair and I can handle anything from custom artwork from the client's reference material (from $80) to printing from a client-supplied negative ($25-$35 per color). My products carry a 100% Unconditional Money-Back, Satisfaction-Guaranteed, No Time Limit Guarantee to live up to your expectations and my claims. I also have a catalog of stock items for $1.00, $3.00 if you want a sample along with the catalog. My address is: Archer Fine Transfers 1205 Silvershire Way Knightdale, NC 27545 email: transferman@mindpsring.com www.mindspring.com/~transferman/ [Q] Why do my decals have ugly silvery borders? [A] schmitz@transarc.com (Don Schmitz 8/95) Decals work best on a smooth glossy surface. If you put a decal on top of a flat painted surface, you get "silvering" - the decal film can't conform to the rough surface of the flat paint and so you get air bubbles under the film producing the frosted look. Assuming you really wanted the flat finish, the solution is to use gloss paint, apply the decals, and then overcoat everything with a clear flat finish like Testor's Dullcote. Its quite common that you can't find the military colors you need in a gloss paint - so the procedure is to paint with flats, overcoat with a clear gloss finish like Testor's GlossCote, apply the decals, and finally apply the DullCote over the whole works. ---------------------------------------------------------------------- Note: the following information was extracted from the previous version of the FAQ compiled by Urban Fredriksson. I've edited out a few repetitive answers in the interest of space, and added the [Q] and [A] style markers that let me generate the table-of-contents section from the source. Many thanks to Urban for putting this together the first time around. ---------------------------------------------------------------------- [Q] What are the basic techniques of painting models? [A] urf@icl.se (Urban Fredriksson) Paint difficult areas first - All kits tell you to paint the smaller parts before assembly. I also paint difficult to reach areas while the model is unassembled. In fact, I ALWAYS paint the wings of the plane before I attach them to the fuselage. this way I can give each the attention they deserve. Once assembled, a lower wing will always receive a second rate paint job. Don't forget to prime the interior of the fuselage black when the halves are unattached. this will brevent the shiny coloured plastic from spoiling the effect of the model. ... I almost exclusively use Polly-S and Tamiya acrylics. To use them with an airbrush, I thin them with a mixture of 50% water, 50% ethanol/methanol and a very small amount of dishwashing detergent. I have the thinning mixture in small glass bottles with drippers. To get the proper amount of detergent: - put a drop of detergent in the bottle - fill it with water, shake and empty - repeat stage 2 two times - fill up with 50% water and 50% ethanol Some people have successfully used windowcleaner instead of this mixture Usually you have to add 40-60% thinning mixture to the paint. It should give a very thin layer, so expect to put on several. To decrease the drying time, you can use a microwave oven. Put a glass of water in the oven to protect it, then put the model in for maybe 30 seconds at half power. In this way I've managed to put on 5 layers of paint in 20 minutes. I have a few tins of enamels, but I use them almost only for .... [A] boebert@sctc.com (Earl Boebert) Let me add a couple of tips from my days of supplanting military pay by painting HO brass locomotives and the occasional custom-built plastic model: 1. Surface preparation is essential; in the case of plastics, making sure that all the parts have been washed to remove the parting agent. Avoid fingerprints. Handle parts with tweezers or wear "finger cots," which are sold in office supply stores and look like miniature condoms; these keep your finger oils off of the surface but still enable you to feel what you're doing. (followups to alt.sex.plastic, please. :-)) 2. Look for the thinnest masking tape you can find; the stuff sold in artist's supply stores is often much thinner and with less "tack" than the automotive/hardware kind. 3. Cut your own strips, using a scalpel and a steel ruler. I would lay the tape out onto a glass plate and cut strips about 3/16" wide. This makes for much cleaner lines, as the rough edge and adhesive "bleed" from the machine-cut rolls is eliminated. If you need more width, add a band of plain paper or (as the previous poster mentioned) aluminium foil. 4. As mentioned, remove tape as soon as the paint has "surface set." Learn what this time is for the paint you are using by experiment. 5. As with anything that mixes craft and technology, the really spectacular results are obtained through a deep understanding of the medium you are working in. What this means is that you find things like brands of paint and tape that work and you stick with them, so that each job becomes less and less a voyage of discovery and experiment. Hope this helps. Earl [Q] I understand pastels can be used to achieve subtle
colour variations, especially for weathering - what kind of pastel should I use?
[A] urf@icl.se (Urban Fredriksson) Use chalk pastels, not use oil-base pastels. Most people use pastels for weathering and highlighting areas on models. I would recommend obtaining a set of shades of gray, and a set of earth tones. I obtained a set of 12 of each ranging from very light to very dark at a craft store for about $4.50 for each set. You can also obtain many individual colour, like shades of green. I've used these for creating the line camouflage on some German aircraft used in Africa. [Q] How do I apply pastels [A] urf@icl.se (Urban Fredriksson) There are several ways to apply pastels. Here are some tips: 1) Make sure the model has a matte finish. This can either be the bare matte paint, or if the paint is gloss, a matte overcoat. 2) Use fine sandpaper or emery boards to make some chalk dust. At this point different coloured pastels can be mixed. 3) To apply the pastel, use a paintbrush, preferably with somewhat firm, yet soft bristles. Alternately, there are cardboard pencil like applicators that can be obtained at craft stores. Q-tips also make a good applicator, as well as pieces of felt. A very good applicator can be obtained from a cassette head cleaning kit. These kits usually have a small handle and pieces of felt used to clean the head of a cassette player. 4) Don't worry if you apply too much, a damp cloth will clean it right off. 5) Use of a sealer coat is optional. Unless you will be handling the model much, one is not necessary, and looks better. [Q] There are so many fillers today. What should I use? [A] urf@icl.se (Urban Fredriksson) The statement that there are many fillers today is quite accurate. As with everything in modeling, there is no one answer as to which to use. It partly depends on what it is you want to fill. Is it a small nick or sinkhole in the model, is it a large seam, or did you do a conversion and need to fill a large area? The answer to this question partly determines what you should use. Also it also boils down to a matter of personal preference. The best way to answer is to tell what is available, give some of the characteristics of each, and some recommendations as to the situations that they work best in. There are those products that are intended as model fillers, those that are fillers for other things, and others. Let's take a look at each type. Here is a partial listing of some of the available putties and other fillers Model putties: Squadron Green Putty Dr. Microtools Supreme Model Putty (red putty) Testor Contour Putty Other model fillers: Mr. Surfacer Non-model specific filler putties: Bondo Other: 2-part epoxy putty thin superglue gap filling superglue Lets look at each kind, and some of their characteristics. Model Putties The most commonly used products are the model specific filler putties. I personally don't recommend the Testor Contour Putty. It was the first that I ever used many years ago. Maybe things have changed with it since, but it shrank quite a bit, and was not based on a solvent that bonded to the plastic. It was also somewhat brittle and tended to flake off of the model if even slightly flexed. Dr. Microtools and Squadron putties are quite similar in performance. They both are based on a solvent, toluene if I am not mistaken, thus they bond with the plastic. They fill gaps well and are easy to sand. They do have some disadvantages though. They both shrink if large amounts of filling are needed, like if you are doing a conversion and have very large areas to fill. They should be applied in thin layers when you have large areas to fill. This helps some in solving the shrinkage problem, but not completely. It also prevents the problem of too much solvent damaging the plastic (I'm almost ashamed to admit this one, but back when I was in high school beginning modeling, I decided Squadron Green Putty would be good to fix some weights into the nose of an F-14. Well, the nose radome collapsed from too much solvent). Another problem is that when sanded, these putties invariably will have small pinhole bubbles in them. Other model fillers One of the best products to come around in a long time for the modeler is a product caller Mr. Surfacer produced by Gunze Sangyo. In my opinion, and in the opinion of several of my fellow modelers in our local club, this is almost a miracle product. "What is Mr. Surfacer?" you may ask. Well, I guess the best way to describe it is that it is a thin filler, almost the consistency of paint. It is the best filler for small gaps, seams, scratches and the like. It can be applied with a paint brush, toothpick, or whatever you like. It dries fairly fast. It dries without bubbles and is very smooth, and sands very well. It comes in bottles in two grades, #500 (a thicker variety) and #1000. It also makes a GREAT primer. It can be thinned with Gunze Sangyo thinner, or as I have used, Dio Sol, and airbrushed. If you don't have an airbrush, it also comes in a spray can variety. Using it as a primer the first time (or any time for that matter) is an interesting experience. Unlike other paints, you spray the Mr. Surfacer on fairly thick. It will look like you have filled every scribed line and obscured every detail on the model, but when you put it aside, go away, let it dry and come back, it will "suck down" tight and every detail will show, and any small sanding scratches or the like will be gone. This brings me to the only disadvantages. It isn't intended for large gaps, but if you layer it, it can be used even for large areas needing filling. It also, since it is so thin compared to putties, shrinks much more. However it's lack of bubbles and quicker drying time more than make up for this. Super glues Super glues also make very good gap fillers. Thin superglues work well for small gaps and scratches. For gaps along seams, put a drop of superglue on a sheet of wax paper, and use a #11 hobby knife blade as the applicator. Put the tip of the blade in the superglue, and run the point along the seam like you were cutting, but don't apply too much pressure. For larger gaps, you can also use superglue combined with baking soda. Put some baking soda in the gap, and apply the superglue to the baking soda. The baking soda will add some bulk giving more filling capacity, and the baking soda acts as an accelerator for the superglue. Thick gel type superglues work very well for larger gaps. I usually use a toothpick, needle, or #11 blade as the applicator. As fillers, superglues have advantages over hobby fillers in that they don't have bubbles when they set. They also shrink very little if any. They also set very rapidly, so can be sanded much sooner. Their primary disadvantage is that they are harder than plastic, so if you are using building a model that uses a particularly soft styrene, the plastic and superglue may not sand evenly if you don't take care to make sure that they do. Probably the best way to guarantee this is to use a sanding block. Also, don't spread the superglue with your finger. For more information on superglues, refer to the section covering superglues in the glues section of this FAQ. Non model specific fillers There are a number of fillers that are not intended for models, but can be used. Most of these are auto body fillers. There are many different ones available. I have not tried any, but others have and have had good luck. One that was recommended was Bondo. It is solvent based, and will bond to the plastic. It also gets harder the longer it sets. It gets very hard, and can be difficult to sand if left to set too long. Epoxies Two part epoxies can also be used for filler. Either the thin, molasses consistency ones or the putties can be used. There are many different epoxies, the long set varieties all the way to the 5 minute varieties. In general, the shorter the set time, the softer the epoxy when it is set. Some of these are even softer than the plastic. Also, most of the putties are not very hard setting either. One of the harder setting epoxies that I know of is JB Weld. It's not too hard to sand, but it is harder than plastic. The advantages of epoxies are that they do not shrink. They do not attack the plastic. Their disadvantage stems from this, in that they do not really bond with the plastic like solvent based fillers. IMHO, epoxies are the least desirable for most filling applications. ... Tipp-Ex for small gaps. Soft but paints well. Milliput for larger jobs. Can be built up rather thickly, and softened during application by mixing in small amounts of water. Home made putty made from plastic shavings and Ethylacetate. Unfortunately dries very quickly, so you have to make it as you use it. [Q] What glue should I use to glue plastic together? [A] urf@icl.se (Urban Fredriksson) That depends on the plastic being used. Lets start with the most common used in modeling, polystyrene. Gluing polystyrene to polystyrene There are 2 ways to approach gluing styrene to styrene. One is to actually weld the parts together and the other is to attach the parts through an adhesive. Which way should you use? It depends. Lets look at ways to accomplish each, and their advantages and disadvantages. To weld the plastic, one could actually try welding, but that isn't practical. When I mention welding the parts, I mean using a solvent to dissolve the surfaces to be joined, and letting the solvent evaporate. Most common model cements aren't cements, but are solvents, and take this approach. These liquid cements are either aromatic or alphatic solvents, ketones or chlorinated hydrocarbons. Here is a list of chemicals that are solvents of styrene and some of their characteristics. evaporation odours cost - Acetone 1 - Benzaldehyde - Benzyl alcohol - Chloroform strong - Dichloromethane - Ethylacetate - Ethyl isopropyl ketone expensive - n-Butanone strong (methyl ethyl ketone, MEK) - Toluene 5 strong - Trichloroethane - Xylene 5 strong 1 very, very quickly 5 slow Commercial liquid cements, what they are made from Testors MEK Tenax 7R Trichloroethane (?) Floquil DioSol Toluene/Xylene (ok, this isn't sold as cement, but it can be used as liquid cement) Editorial Warning: A reader who should know pointed out that many of the chemicals listed above are extremely toxic and/or carcinogenic. It is unlikely that any hobbyist working in their basement/kitchen can hope to use these safely. Given the variety of commercial products available, at quite reasonable prices at the local hobby/toy store, it seems silly for anyone to use something like chloroform to glue their models together. Please use common sense and lots of ventilation. - Don Schmitz. [Q] How do I used liquid cement? [A] urf@icl.se (Urban Fredriksson) For most seams, hold the parts together, not too tightly, and use a brush or needle applicator to apply to the joint, allowing capillary action to pull the cement along. Once cement is applied, press the parts together tightly and clamp (rubber bands work well for the fuselage of aircraft). If the seam fits well, the little molten glue/plastic combination that oozes out will fill the gap and can be sanded when the cement has dried. Little filler should be needed. [Q] Which cement should I use? [A] urf@icl.se (Urban Fredriksson) That is a matter of personal taste. I have personal experience with Testors, Tenax, and diosol. I like Testors very much for most applications. I usually let it set up overnight before removing clamps and sanding. I like to wait longer if I am not too eager to work on the kit. It produces a very solid seam. Diosol is very similar. Tenax 7R sets extremely fast. With Testors, I sometimes apply to flat surfaces then mate them. This is impossible with Tenax. You have to use capillary action. The joint is dry enough to sand within half an hour, shorter for small joints. It welds the parts, but because of the speed of evaporation, I have had bubbles for surfaces that didn't mate very well. It is fantastic for surfaces that mate very well. Ethylacetate is very thin giving it good capillary action capabilities. It evaporates rapidly, is reportedly less harmful than those containing Tolouene and Xylene, and is cheaper. [Q] With the proliferation of vinyl figures, what should I use to
glue the parts?
[A] urf@icl.se (Urban Fredriksson) One suggestion is to try cyanoacrylate, or superglue. [Q] Of what kind of plastic are soft drink bottles made? [A] urf@icl.se (Urban Fredriksson) Soft drink bottles are made of PETE plastic. PETE is an acronym for: PolyEthylene Terephthalate Ester or more commonly, polyester. Apparently, Kodak makes about 80% of the plastic soda bottles used in the U.S. Additionally, DuPont and Hoechst-Celanese also manufacture polyester. A big reason is that Kodak, DuPont, Himont, and Amoco are all major manufacturers of purified terephthalic acid, one of the raw materials used in making polyester. [Q] Are their solvent type cements that can be used to join PETE
plastic like there are for styrene?
[A] urf@icl.se (Urban Fredriksson) Yes, there are, but they are pretty nasty substances. The known solvents for PETE are: phenol o-chlorophenol dichloroacetic acid trifluoroacetic acid hexafluoroisopropanol pentafluorophenol methylene chloride/hexafluoroisopropanol tetrachloroethane/phenol 1:1 and various combinations of other chlorinated alkanes with halophenols One would generally not like to use these at home. [Q] What can I use then to join PETE? [A] urf@icl.se (Urban Fredriksson) Probably the best would be to use superglue. Some use PETE as wing- tip protectors for flying model airplanes. They recommend roughening the plastic with 100 grit sandpaper and using gel type gap filling superglue to attach it. Hot melt adhesives, such as those used in glue guns, is also a possibility for the adhesive, but superglue is probably better in most modeling applications. [Q] What do I use to glue together dissimilar materials? [A] urf@icl.se (Urban Fredriksson) There is not one pat answer to this. 2 part epoxies and cyanoacrolates are probably the best. And depending on the application, one could also use contact cement. [Q] What do I use to glue together to metal parts? [A] urf@icl.se (Urban Fredriksson) This is particularly important to figure builders, since many figures and parts are made from white metal. One of the oldest and probably best ways is to join metal parts is by soldering them. If you don't want to learn to solder, then adhesives can be used. If the parts mate very snugly, particularly 2 flat surfaces, superglue works very well. For surfaces that do not mate quite as well, gap filling thick superglue is one option. 2 part epoxy is also something that can be used. [Q] What should I use to glue wood to wood? [A] urf@icl.se (Urban Fredriksson) The best glue for wood is Alphatic resin, carpenters glue. It produces a joint that is stronger than the wood itself usually. [In the US, Elmers is a common brand - the yellow stuff sold in hardware stores, *not* the white glue sold most everywhere else.] [Q] What should I use to glue wood to styrene? [A] urf@icl.se (Urban Fredriksson) There are several options. Some suggestions are: 1) You could try using superglue with an accelerator. This would probably have to be thick superglue, unless you are using a very dense wood. Thin superglue would tend to absorbed by the wood like a sponge. 2) 2-part epoxy would probably be best, since it works well at joining dissimilar materials. 3) If the styrene is thick enough to withstand heat, hot glue may work well. [A] jkerns1@ford.com (Jim Kerns) Gluing Styrene to wood or paper is a pretty typical thing to do when assembling flying model rockets. Tube type plactic cement works fine - that's what Estes recommends. CyA also works. Glue soaking into the wood really isn't much of a problem. I use thin CyA to attach balsa fins to paper body tubes all the time - hold the parts in place and add several drops of CyA. It does soak into the end grain of the balsa and the paper tube so you have to use several drops instead of just one drop like you might between nonporous surfaces, but it works quite well. [Q] It seems that the super glue that I am using glues my fingers
together better than the parts, why?
[A] urf@icl.se (Urban Fredriksson) This is quite natural, considering why cyanoacrylate was developed. It was developed for doctors as a way to seal wounds without sutures during Viet Nam. In the field, with the many wounds, if a way existed to quickly seal a wound with out stitches, more people could be saved. So, biological things such as fingers are joined very well by CA.
rec.models.scale FAQ, part 5

FAQ Table of Contents