Originally Posted by
WLIU
One likely answer is that modern finishes fail before the fabric so external observation of the condition of the finish is all that is needed.
The Grade A and dope covering has the characteristic that the cotton is attacked by moisture and bacteria (mold) in ways that modern polyester fabrics are not. And the cotton absorbs the dope. When the finish is observed to be failing, that means that both the dope and the cotton are failing.
In contrast, my experience and observation of modern fabrics and finishes leads me to believe that the finish, be it dope or Cooper Superflite, has the failure mode of losing its bond to the fabric, leaving the fabric at full strength initially. If the finish is not repaired, then synthetic fabrics will start to degrade, but usually the owner responds to the ugly looking situation by repairing the finish. Or if the finish and fabric is old or too ugly, ripping off the old fabric and recovering. My Pitts S-2A was recovered when the work of fixing the butyrate on Ceconite got to be too much hassle. Looked at some sections of the old fabric and an informal pull test between two guys seemed to indicate that the fabric was fine but the dope had simply gotten brittle and the dope to fabric bond was failing.
So perhaps we do not need any testing of modern finishes at all beyond the old mark 1 eyeball. When it looks bad, fix it. Skip messing with testers.
Best of luck,
Wes
N78PS recovered with Cooper Superflite