I have colored silk from Sig for my Ringmaster wing.  Usually I brush dope on silk and paint over the silk.  This time I am going to leave the silk as is with just a clear dope finish.  I also have an air compressor and a hobby type spray gun with a 4 oz. cup.  What would give me the best looking finish?  Should I brush the dope or spray it?

The problem with brushing dope on silk is run through, where blobs of dope accumulate on the inside and dry to give a mottled appearance.  I deal with this by brushing the first coat about 70% thinner, 30% dope.  The run through is inconsequential.  You want dope to go through as it will make the silk more transparent. Couple of coats like that then thicken up the dope a little.  Keep brushing and thickening until all the pinholes are filled, then put on enough coats to get the degree of shine you want. 

George Aldrich clued me in to a great technique for doping silk.  He recommended use of a disposable foam brush.  You just dip about 1/4" of the end into the dope and then gently draw the brush across the silk.  You get really long strokes, and rarely have brush through.  If you do get a puddle inside, just turn the model upside down and brush from underneath to draw the dope back out again.  I used that technique the last two silk jobs, and his advice proved golden.

I was just going to suggest that, Larry--we used to hold the model overhead and brush from underneath.  Except using a standard brush. (Didn't have foam brushes back when I was still using silk and dope). Absolutely no accumulating on the inside.  Also a pretty good isometric exercise for the arms...

--Ray

Hi Ray,

I have mentioned that technique several times before.  It really does work!  

Foam brushes work fine with dope, don't react with it...I don't know about cleaning with thinner, etc.  though.  I just throw 'em away after one use, when I use them at all.

--Ray