Rabble Rousing (more painting stuff) ;-)

Well, I guess it's time to shake the tree a bit. I'm just getting ready to start finishing my latest creation. Now, I've been known to do a foolish thing or two in my time (any of you on RC Online will remember my trails with paint last Spring). The plane design is radical enough as it is, so I plan to use some pretty standard methods for finishing. Howard Rush and my recent experience using auto lacquer had just about convinced me to try using Ditzler or similar, but I'm chickening out and going with dope. I'm going to just step out and use Sig Litecoat and my own toners, but that isn't much of an experiment since I've already tried it on a test finish (my son's Banshee) and it worked fine.

Now, after that long preamble, I have an actual question. Any suggestions as far as maybe semi-locally available reducer (thinner) that will work with Sig Dope? I had used DuPont 3608, but that's not available any longer (at least not in the EPA Secret Police controlled Northwest). I'm afraid to try anything like V3608S and even it is difficult to come by. I'm also not too thrilled about ordering Brodak thinner by the quart (I tend to use a lot when finishing). I did find a place that sells lacquer auto paint and reducer (mostly DuPont and Ditzler) for car restoration work in limited amounts, but at the prices this guy charges, I'd rather go with Brodaks at $10 a thimble-full.

So any other bright ideas, or do I just kick out for Brodaks and grit my teeth?

Thanks,

Dupont 3608S thinner is the stuff we used with SIG. Are you sure that this has changed? I was under the impression that in those areas where it is banned that the number had changed slightly when they reformulated it.

That said, if you were willing to buy Brodak thinner (at the admitted higher price), then I would certainly recommend going all the way and using all Brodak dope. You get a lot more dope for your money, so the higher price for the dope isn't really higher after all. And the thinner is the key to the system. That is what allows it to dry so quickly (and to quit smelling so quickly) and to be able to be sanded so soon. Remember, there is some thinner in the dope already when they formulate it, even though it is much thicker than SIG's. We have heard reports of some people buying Brodak dope and using someone else's thinner (even Randolph's thinner is different stuff. Brodak dope is made by Randolph, but to a different formula than the "real" aircraft dope they are noted for making.), but using a different thinner defeats the purpose of Brodak's dope. Use what is made for it and you will be very happy with the product. We have a bunch of SIG dope and 3608S thinner that just went downstairs. Even though we already have some of the stuff on hand, and can still buy the Dupont thinner wholesale by the gallon (it is not banned--yet--in our area), and even by the 5 gallon lot--and with no added shipping--we have switched to using Brodak dope and thinner because it is that much better.

And, yes, Matt has tinted his own colors using Brodak clear on a desert scheme, and it worked fine. Ten dollars a quart may seem like a lot of money for the Brodak thinner, (It is $35 a gallon when you can pick it up direct, so the gallon lots are not that much cheaper), but how much does your whole plane cost, and what is your time worth when you don't have to wait so long between coats? I might add that even though you have to thin the dope before using--even before brushing because it is that much thicker--you will still end up using less dope and less thinner in the over all project than if you started with SIG dope. The SIG doesn't cover as well, so you use more coats, more layers, and then spend even more time in waiting for it to dry.

Matt's first front row finish came with using Brodak dope.

Free commercial over.

If you still must use your Sig stocks due to economic considerations like I have to do. I find that PPG Ducaryl 876 (medium) Acrylic Laquer thinner works extremely well on Sig Dope.

Dupont 3608S is certainly not the only brand or formula that works well. Each brand has a similar equivilent type of thinner that should work. The key is to get something that disolves well and has a similar drying time. Some cheap stuff that we got works to clean the paint gun, but not much more. Watch drying times very carefully. If it is too fast (Brodak excluded which is formulated for our purposes) the acrylic lacquer thinner may not "bite" and the upper layers will peel. If it is too slow, it will "melt down" into the bottom layers and you will end up with a mess. You will also find it bubbling later on when it skins over, but is still gassing off underneath.

The Dupont we know works well. If someone sells another brand, check with them to see what is similar. They should have a chart that will tell them.

>>You will also find it bubbling later on when it skins over, >>but is still gassing off underneath.

Leonard,

Well, this is pretty much what happened to me last Spring using Sig and 3608 on the substrate and Brodaks on top. It's ugly, don't do it.

I live in Puget Sound area and DuPont 3608, 3608s and v3608s are simply not available. Ditzler pPg stuff is available and semi reasonable as I noted.

Hear's the deal. I have about 3 gallons of Sig Litecoat and can mix my own colors (as I've noted before). I also have 2 gallons of Randolphs (the blue tinted base coat stuff). I'm not real thrilled about the idea of using it for weed killer and putting out a bunch more for Brodaks. Not that I'm complaining about cost really. I just hate to waste the stuff I have. It's sitting in a 40 degree fridge and should keep for a bit.

As I've noted, for my environment (cool and humid most of the time), 3608 worked the best and most consistent. v3608 was ok if the humidity was down. v3608s doesn't work at all. I haven't tried the ppg stuff, but I'll talk to my guy at the paint shop and see what he has to say.

You really sholdn't need to refrigerate it. All you need to do is to keep the thinner from evaporating. In fact, dope can get pretty thick and still be saved by adding thinner and stirring it up. But the best trick I have learned to keep it from--and this works for latex paints as well--is to make sure the lid is tight on the can (or bottle) and store it upside down. Any minor air leak in the lid then becomes self-sealing.

but, as I say, make sure the lid is tight. If you have it in a place that gets warm in the summer (like a garage) this could get disasterous. If you have it stored in a refrigerator, I would take it out and let it warm up to room temperature. Pop th lid and then reseal it to take off any pressure. And then you should be able to store it indefinitely upside down at room temperature.

I understand your desire not to waste the stuff. The Randolph tinted clear is sort of Lite Coat by another name. This stuff is made for "real" airplanes, and the tinted base is to show that it is non-taughtening. It should work well for base coats before you apply the color. Use the same thinner for this as you use for the SIG, and you should be able to "mix and match" OK. As I say, the thinner is the key to Brodak dope. And since all dope already has some thinner in it, you can't merely use Brodak thinner with something else to get the same advantage. But regular Randolph and SIG are close enough that if you use a common thinner that is also similar to what they are formulated with, they will work compatibly together. Just watch that you don't use something that is too slow drying or you will get melt down.

Leonard Neumann

Jim,

Thanks you. This stuff, the Duracyl 876, is acutally available at a reasonable price (if you call $28 a gallon reasonable, but hey...).

You didn't mention Sig thinner. It's cheaper than Brodak and I've found it works a lot better than 3608s for the clear coats when you're using Sig dope.

However, I'm switching to Brodak for all my new masterpieces. To save a few bucks, I still use 3608s for cleaning out the spray gun, but the Brodak dope goes on very nicely and is better behaved.