After experimenting with some of the newer
finishing materials and paints, none have really given me the satisfaction
of a good, old-fashioned silkspan and dope finish. Dope, however, is a relatively
high cost option, both for nitrate and for butyrate. There is a way to help
bring down the expense by buying it by the gallon, if you don't already
do so. Sig and Brodak are fine dope products, but even in the quart size
cans it costs 2x to 3x the amount of getting it by the gallon from Aircraft
I have a vintage Carl Goldberg 1/2A Skylane configured for
control line that is now in the process of being covered, and a vintage
control line Sterling F4U-1 Corsair is nearing completion of the construction
so it will be getting covered soon. On top of that, I have a vintage Top
Flite P-40 Warhawk control line kit that will be next in line for building
and covering. Finally, plans and balsa have been procured for a long-awaited
control line Douglas DC-3 control line model that will also be covered with
silkspan and dope. That's a lot of dope to buy. Naturally, I want to save
money wherever possible, so buying in gallon quantities makes sense.
For example (see photo below), a gallon of butyrate clear dope costs
$49.00 by the
from Aircraft Spruce. The largest can of clear that Brodak sells
, for $23.89 (Crystal
is $32.99/gal., but is not equivalent to the Randolph product).
That works out to $95.56 per gallon (95% more). Fortunately, Aircraft Spruce
also sells white butyrate dope by the gallon for $76.25. Brodak only sells
color (including white) in
cans at $16.49. that works out to $131.92 per gallon (73% more).
Butyrate thinner from Aircraft Spruce costs $42.70 per
. Thinner from Brodak is costs $18.19 per
That works out to $72.76 per gallon (70% more). So, as you can see, an overall
cost saving of 75-80% can be realized when buying it by the gallon.
The best bet for buying color other than white is still through Brodak
or Sig, because it is $60-$85 per quart from Aircraft Spruce. Here is the
insane thing: Buying it buy the gallon costs LESS at $55-$75 per gallon
Go figure. If you need enough colored dope to buy it by the gallon, then
it's a great deal.
Randolph Butyrate Dope and Thinner by the
Here is a tutorial I did on
silkspan and dope
. It include a few videos of the process.
Posted October 25, 2012