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Building Tips and technical articles. => Paint and finishing => Topic started by: adam collver on March 18, 2014, 09:45:33 AM

Title: thinner to dope ratio
Post by: adam collver on March 18, 2014, 09:45:33 AM
I was wondering after you cover with silk span and put on colour for your top clear coat what would be the thinner to dope ratio.

Thanks
Adam
Title: Re: thinner to dope ratio
Post by: Tim Wescott on March 18, 2014, 09:58:15 AM
That depends.  You want it thicker for brushing, thinner for spraying.  For all I know, if you've got an HVLP system you'll want a different viscosity than for old-style.

Now, if that doesn't make things vague enough, different brands of dope are thinner or thicker in the can -- Sig and (I think) Brodak are thinner, Randolph's is thicker.

Ideally you thin enough to get the right consistency, not to get some specific paint/thinner ratio.
Title: Re: thinner to dope ratio
Post by: adam collver on March 18, 2014, 10:21:01 AM
Thanks Tim Im using Randolph's and I'm brushing it on, before I colour and then span is on how many coats of clear do u put on before colour?
Thanks
Title: Re: thinner to dope ratio
Post by: RC Storick on March 18, 2014, 10:34:58 AM
About 3 coats will start to give a sheen sometimes four. Then apply color and apply clear after that. This all varies on your technique in application.
Title: Re: thinner to dope ratio
Post by: Dennis Toth on March 18, 2014, 04:42:57 PM
Adam,
You might want to look at the Preval spray system. This is a simple cheap self contained spray system available from Home Depot. Here is the Preval web site http://store.preval.com/?gclid=CP_R-5SGnb0CFQ8OOgodvnoA1w. Each unit can cover 2 - 35 size ships. If you spray mix the clear 50/50, watch the temp and humidity (less than 80F and 68% Hum). If the humidity is higher you will need to add 1 -2 % retarder. Wait at least 1 hr between coats, 2 should do it for a top coat. After complete let it gas off at least a week before you fly.

If you brush, I think 40/60 thinner/dope. Use a very soft brush apply in one stroke to avoid softening and smearing the color.

Best,        DennisT