Using Testors Glosscoat as a sealer

[falcongeorge]

I have heard on another board that testors Glosscoat (the old-fashioned stuff that turns yellow) will work as a sealer to prevent laquer from etching plastic. Anyone tried this? Not interested in theory, please only respond if you have actually TRIED it.

[hogs29]

I wouldn't do it. Even though many people have, using extremely light coats gradually built up, been able to put lacquer over enamel, it's just not supposed to be done.

I know a guy that swore he could do this time and time again, disregarding all the warnings. And it worked for him until he got to a project he had spent ages modifying the body on, getting it just so. That's when science finally caught up to him, or at least Murphy caught him.

Facts are facts, lacquer will attack enamel when sprayed over it, and even though it is possible to do, there is no gaurantee when it will or will not work.

Use a good automotive grade primer. I stay away from Duplicolor now. It tends to attack the softer plastic being used in the newer Revell kits. Plasti-coat has worked great for me over that stuff.

[falcongeorge]

I dont think its enamel. I think its a shellac. Smell it. Doesnt look like anyone on here has tried it. I will give it a shot on something when I have time.

[Guest zebm1]

shellac is funny stuff......here's some research...

What is Shellac?

Shellac is an animal product, a resin secreted from the Coccus lacca (lac beetle), a scale that feeds on certain trees in India and southern Asia.

After hatching, the nifty little bug snoops around for a place to eat, selecting a stem or leaf as its breakfast counter. It has a sharp teensy beak, and it uses that to puncture the tissue of the plant, and settle in for a lifetime of sucking nourishment.

After feeding, the insect secretes a resin, which dries and hardens into a protective covering called lac. The lac is collected, crushed, washed, and dried. After cleaning and heating, it is drawn into thin sheets of finished shellac.

The level of refinement, the timing of harvest, and source of the lac,

determine the specification color that comes to you, the happy woodworker.

Who uses it?

The largest uses for shellac are for the food, drug, and cosmetics industries. Fruits and vegetables in the produce aisle of your favorite grocery store are coated with shellac and wax to make them shiny and eye-catching. In the world of cosmetics, women (and men) use shellac-based hair-spray to make themselves appear shiny and more eye-catching. Many vitamins, pills and food supplements are coated with shellac to make them slide easily down your throat, into your tummy. Of course the most important use of shellac, in my not-so-humble opinion is as a woodworking finish, where you can make your projects shiny and eye-catching. Are you sensing a pattern here?

Other Features of Shellac

All shellacs imbue some bit of color to wood. They also won't yellow as much with age as other varnishes and lacquer (though it does change subtley with exposure to light)

Barrier coat - prevents stains and finishes with same base, i.e., oil-based stain and oil-based varnish, from bleeding (ghosting) into one another. Works similarly with lacquer stains/varnishes. Also a good barrier between incompatible finishes.

Stops pine pitch from bleeding

Dries hard, and won't gum-up like oil finishes (perfect for bookcase shelves).

Easily repairable (new finish melts into previous layer)

Outstanding clarity, really pops the grain of those wild grained woods

Tintable - avoid uneven staining by tinting your projects using colored shellac. Gives complete control over how much to tint your project. You can use a nearly infinite combination of the various shellacs to color your project, for example garnet over a seedlac washcoat, then French polish with blonde.

Dries quickly. Avoid the problems inherent with varnish (dust specks, bubbles). You can recoat thin coats (recommended) in usually less than two hours.

Problems are easy to fix - level your finish with a hand-held scraper, simply slice off runs or sags with a razor, blushing (water vapor trapped in the finish) fixed by wiping down the finish with 1/4# cut shellac-soaked rag.

Non-toxic when dry. Shellac is a USP-approved food coating. This doesn't mean you should grab a handful of flakes and eat it! I'm not selling food here, I'm selling wood finishing supplies.

Easy on your tools. Forgot to clean your brush? No problem. Fully-dried shellac will dissolve in alcohol or water/alkalai solution.

It makes sanding and planing difficult woods easier. A spit coat stiffens the wood fibers, allowing the cutting edge to shear the wood cleanly.

If you're stripping porous wood, and the stubborn pores still have gunk in them, you can apply shellac, then strip it again and the shellac will pull the gunk out!

Got a greasy spot on the wall of your house? Dab a little shellac on it, and come back and paint it two minutes later; the grease won't bleed through!

Hope this helps, if yu want more details go to this website...

http://www.shellac.net/information.html

zeb :wink:

[ramonesblues]

Zeb, that is the most comprehensive analysis on shellac I have ever seen. Bravo Sir! In the old days we used to spray Endo shellac on synthetic enamel as a bleeder sealer,i.e. white over red.Worked great. Not sure how long they lasted, as they were usually economy paint jobs.

[chopt31]

I'm a shop teacher in my "other life". I've suddenly got an urge to try shellac! I usually go with more modern spray finishes but I'm seriously impressed with your shellac tutorial! Thanks for an inspiration! Working with kids the safety issues surrounding any finish material is always a concern. With plastic, however, the line of modern Tamiya sprays is just too easy to work with. Their primers, flats and gloss finishes just totally make the paint portion of building a pleasure. I can't see ever using Model Master again. I just wish the hobby shops in Honolulu could do a better job of keeping the supply adequate to meet the demand.

[Zoom Zoom]

I'll have to test the Testors clear to see how it works, also need to test Future as a sealer. Most new kits, even molded in color, don't seem to have a color bleed issue, but they often have ghosting/crazing issues if there's any bodywork and the top coats are automotive paint.

Zinsser B-I-N is a white shellac based primer/sealer that you get at Home Depot or Lowes, comes in cans for brush/airbrush, or tall spray cans (lousy nozzles) that you can replace the nozzle or transfer to airbrush. I know from experience that it's a great sealer. If you have doubts whether you'll have any problem with using a hot automotive paint on your model, you really need to use a sealer like this. Just apply a quick coat of regular primer first (whatever you like, Tamiya, Duplicolor, Plastikote). Then apply the B-I-N after it's dry. You can then paint anything over the B-I-N, it's a great primer that you can shoot color over, or more of your regular primer. B-I-N is thinned w/alcohol. It sands to a fine powder.

Some people swear by Variprime as a sealer. I swear at it :wink: . It did not work for me as I had hoped, it's incredibly hard to mix (as are other sealers from MCW and B-I-N in pint/quart cans), and it's incredibly toxic to breathe. It's expensive when you buy it and the reducer. People who use Variprime and like it don't want to hear that cheaper/less toxic sealers actually work better for a loudmouth like me . My point is if you are in the market for a sealer, start with something like Future or B-I-N or Glosscote and see for yourself if that works before going nuclear.

[Guest zebm1]

Actually, tha tutorial is not mine, tha website that I listed is where I found tha info. I believe that the guy who wrote this piece also sells hi-quality shellac from that site as well.

I just copied and pasted tha info for all of us modelers, as I prefer to let tha eggsperts, in their fields of endeavor, do tha explaining.

As a trained paralegal, one of my skills is an ability to do extensive research on tha web, around tha world. I have search engines going back to tha mid 90s. Almost nothing ever gets erased offn server mainframes, most are afraid to erase old entries because of tha crossfeeds and tha volitility of erasing 1 post causing several other posts to disappear as well. Is tha one thing I thank King Gates for....making Windoze so accessible. When I started cruising tha web, Netscape waz tha premier internet OS, and it waz FREE.

zeb

[ramonesblues]

They don't call Vari-prime green death for nothing. its excellent for ground coating metal as a rust preventative, but the risks are not worth it just for models,imho.Plus, its incredibly expensive.

[Modelmartin]

I have been using PPG acyrlic lacquer primer on all of my styrene with no problems whatsoever! I used to use Duponrt but they must have changed the formula because it started splitting :cry: when it dried like a "distressed" finish. I changed to PPG and Voila! Perfect results.