What's the dope on dopes?

I've only used film and enamel (Flair Spectrum) so far.

Does Butyrate shrink covering?

Do I have to use non-shrink dope on fuselages?

Tony

>I've only used film and enamel (Flair Spectrum) so far.
>
>Does Butyrate shrink covering?
>
>Do I have to use non-shrink dope on fuselages?
>
>Tony

You bet.
You don't HAVE to use low-shrink dope on solid surfaces, but many people do.

Jake

>Does Butyrate shrink covering?
>
>Do I have to use non-shrink dope on fuselages?
>
>Tony

"regular" butyrate dope will shrink when it dries and shrink the surface with it if it can. Some dopes have plasticisers in them to keep them from shrinking (as much). SIG "Lite Coat" and all of their colors are listed as "non-taughtening". Their regular butyrate is used for shrinking covered surfaces. From there you go to the other. Brodak dope seems to work well in most applications. If you are using a "stick and tissue" type of construction, however, you may experience some warpage. The structure of most of our airplanes (not all) will withstand the shrinking with no problem. Still, it is good to dope the top and bottom of a wing at the same time. This will even out any pressures from dope shrinking. And you need to take care in the fillet areas to make sure they remain clean and you don't over load them with dope. Otherwise you may get lifting (bubbles) in these areas.

But mostly, it is easy to work with, it is light (when you don't overdo the coverage--especially colors.) And it is very easy to touch up when you need to fix litle dings and dents (or even larger patches) which is something that is far more difficult to do woth automotive finishes. On the downside, dope takes longer to do. Brodak dope dries considerably quicker than SIG and also has a less pugnatious and lingering smell. (Both good qualities--especially the smell.)

Tony, I forgot for a moment that you were in England. I don't know what dopes you have available to you there, but I used our commonly available brands of dope here in the US. You can add plasticisers to any butyrate dope if you are worried about the top coats shrinking too much.

So, what brands are available to you there? (Remember, you can use the stuff that the RAF uses if you want.)

The full range of Brodak butyrate dopes are available from Paul Smith who advertises regularly as PSAeroproducts in the UK comics and there's a plethora of nitrate dopes (shrinking and non shrinking) availble from a variety of UK manufacturers.

I have used nitrate dopes for all of my diesel powered planes as it is not affected by the fuel.

I have painted a couple of mini Goodyear C/L team racers with Brodak dope.

I much prefer the smell of nitrate dopes to that of the butyrate dopes.

If Tony wants platiciser he can purchase tri-cresyl phosphate from Mike Woodhouse a free flight at http://www.freeflightsupplies.co.uk don't worry Len, very few of his products compete with yours

From what I understand butyrate has a gentler shrink though I have not compared the nitrate and butyrate dopes against each other on an open structure covered in tissue .

LAST EDITED ON Feb-18-04 AT 06:24 PM (CDT)
 
"From what I understand butyrate has a gentler shrink though I have not
compared the nitrate and butyrate dopes against each other on an open
structure covered in tissue ."

Nitrate generally tends to shrink to a certain point and then it pretty much quits. Butyrate it seems "shrinks on forever". The only real reason butyrate dope was developed at all in the first place was because of attempts (in the late 1930s) to find a dope for full-size aircraft that was more fire resistant than nitrate. The alcohol fuel resistance bit for model airplanes was never even a consideration then.
Nitrate doped fabric tends to go up in a flash- and if you are the guy inside the airplane at the time, that is probably not a real happy thing to have happen.

Jake

Tony

Mike Woodhouse at Freelight Supplies.co.uk stocks a plasticiser.

Good flying

Here's an interesting source for the compatibility of various finishes - what can be applied over what . . .

http://www.modelflight.com/chemical.html

Several other reference tables, as well.

Tony,
If you use butyrate from Paul Winter you are on your own, I'm afraid.
If you use regular nitrate dope, use only HMG or Britfix. Don't even think of using Irvine dope. For plasticiser, add one tablespoon of castor oil per 1/2 litre of dope (clear and colour). Fuelproof with Aerocote.