Originally Posted by Lou Crane

Bob J and Clean
(Hi, Clean, it's been a while. Good to see you again!.)
(Bob, any further word on the K&B .28 scheduling?)

One thing I think I noticed missing so far ... how much nitro are we talking about? Nitro is an extreme solvent ...

Butyrates stand up pretty well to 5% nitro fuels, in my experience. 10% gets iffy, moreso if raw fuel sits on the model. With luck, a spritz and a quick paper towel, you may prevent 10% to maybe 15% nitro giving a foggy white appearance like blushed dope.

Epoxies are supposedly more resistant - only tried that way once, but It came out heavy! I know, practice and technique can overcome that. However...

Odd thought... not for most of us: diesel fuel and exhaust residue don't do well with dope finishes - they yellow light colors; don't wash out with cleaning solutions and even straight isopropyl doesn't bother them. Also, ether or kerosene in them seems to dissolve, or dissolve into, enamel finishes. Does kerosene act too much like turpentine (aka: "mineral spirits?")

Incidentally, Bob, 20 or likely more years back, the EPA was really cracking down on 'volatile organic solvents'. At one time, it got so you couldn't mix a newest batch of Aero-Gloss with the previous batch. SIG paints were a bit better off. SIG has survived, I think. Has Pactra resumed production of "CAB" (Cellulose Acetate Butyrate) dope? If you have either current, or a stash of earlier, compatible A-G, Fantastic!

...Some of this explains the extreme cost of today's model airplane dope and the newer possible substitutes for it?

There are automotive finishes compatible with butyrate dope. You may have a nearby auto paint store that can mix pigments into straight
Randolph butyrate Clear for any color ever used on cars, boats or (people-carrying) airplanes... Possibly in as small as a quart volume....

A little attention to technique! - they can build up weight in a hurry, but cover very well even used sparingly.

They were developed for auto repair/rebuild/custom shops, for reasonable labor hours billing. Generally, they flow out well, 'cure' (at least to sanding/buffing extent) quickly, and "sand" ( w/1000 or 1500 wet or dry, or rubbing compound ) within hours. Traditional butyrates did better with several days to a week curing... (but, thinned properly, usually came out lighter.)

Just some ramblings...