I couldn't agree more. I've found that water-based ANYTHING is a disaster for fins.

Joe

I use lacquer primer exclusively and haven't had any problems with it going over Fill-n-Finish.

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I love sanding.

Heck, I'm getting high just reading this thread

Doug

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YORF member #11

I haven't either. But we usually apply it in thin coats, and it dries fast, so any effects will likely be very shallow and get sanded away.

I suspect if you hit a spot with straight lacquer thinner, you would see more severe effects.

As for dope, I've taken the FnF fillets right off a rocket with it Not only will the dope cut FnF, it'll cut red body putty, too. You have to be extra careful with it. You pretty much need to put the dope at the bottom of the pyramid of compatibility - just about anything can go over dope, and dope can't be put on top of anything else (except dope). That's been my experience.

BTW, I've lifted the red putty off a rocket, too

I believe I could be heard saying dumb@$$ to myself...

Doug

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YORF member #11

I agree with you Doug; in my finishing process, Dope's in the foundation.

Many years ago, I used to use water-based products, like airplane balsa filler, to fill the grain on fins and other balsa parts. But I soon found I disliked the amount of sanding dust, and especially with thin fins, found that it was difficult to control warpage. That's a risk one takes with water-based products applied to paper and wood elements.

I'm cut from the same piece of tissue as GH; I like using Nitrate dope (because it shrinks less than Butyrate dope) and tissue (OO or GM weight silkspan) to cover fins. It takes about 3 successive coats to fill the silkspan weave and grain depressions (with sanding in between) to get to the primer stage, but with far less dust and mess, and very little risk of warpage. And to your point, so long as dope is the starting point, just about anything will go over the top of it. It's very resilient.

On the other hand, this finishing process can take longer, and the Supreme Commander has been known to sniff somewhat unappreciatively on her occasional GAO inspection tours to the shop, remarking somewhat pointedly like "what stinks"?

In the end there are often several ways to skin a cat, so to speak, with it coming down to preference, and the compromise one's willing to accept stemming from a combination of convenience, speed, cleanup, and results. The important thing is to find a method and material set one's comfortable with, and then practice, practice, practice. It's proficiency that will drive towards those sought-after results.

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John
YORF #003
SAM #004

Lacquer primer over F-n'-F is fine as long as one uses reasonably thin coats. Laying it on thick can and WILL cause F-n-F to lift clean off the material it was applied to if thick such as filling dents or for fillets.
One can coat over the Lacquer primer then with the choice of Lacquer, Enamel, Urethane, or two-part Epoxy paint (which is darn near impossible to find due to enviro-NAZIs), but NOT Color Butyrate Dope as that will burn right through the Lacquer Primer down to the F-'n-F making a horrendous MAYHEM-like MESS.

Years ago, Pactra made a primer that was a "Less Hot" Dope-base called "Pactra Prep" that could be shot over just about any filler materials including water-based F-'n-F that WAS actually compatible with Color Butyrate Dope topcoating. I sill have two quarts plus a pint of the stuff in fresh cans, but it has been gone from production for at least 15 years (prior to Midwest, then RPM (Testors) taking over Pactra).
Real bummer that stuff is gone too as it by far was the BEST primer I have EVER shot out of my gun and airbrush for finishing rockets.

The nostalgic "olde-tyme" hobby-shop aroma of nitrate and butryate dope products ALONE almost makes them worth using. There is a special technique in knowing how to use these products, but most never look back and stick with them once they get the hang of it.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !

Amen GregGleason!

I hear ya bro!

The power of dope to the sinesus!


Yeah brother!

Dittos on that. GH steered me to acetone as thinner for SIG sealer in a past thread on this subject. I have a bottle that tends not to seal all that well, apparently, and I've re-thinned it with acetone numerous times.

I used mostly Aerogloss brand as a kid, but tend to buy SIG now, since Hobby Lobby carries it, and I can get it using the 40% off coupon.

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Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp

That happened to one of of my models-in-production. I put sanding sealer over a boat tail which I'd filled with Fill n Finish.

I plan on sanding it down and starting over when I get my enthusiasm back.

For basic fin filling I gave up on Aero Gloss sanding sealer which I've used since 1978 and now just use Plastikote automotive spot filler and primer 100% of the time. I use Fill-n-finish followed by the Plastikote primer on nose cones... Its hard to warp a nose cone .

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Scott

NAR #32070