From djpil
Randolph fabric and dope would be my first choice.
Well...Randolf WAS our first choice...applied by a very experienced guy that raved about Randolf and has used their products for the last 25-30 years. Was applied by the book. The products were supplied ex-Australia from the Australisian supplier.
We picked the aircraft up on 1 March, and within a week the fabric appeared to be lifting around the top tank (Pitts S2B), and the dope around the top fuel cap departed company. We returned the aircraft for repair. Then a few days later this occured...
The tape lifted and the patch of dope is somewhere in the Central Hawkes Bay!!!
This is apparently not unheard of...Aviat has stopped using Randolf ceconite/Rand-o-proof/dope systems and has reported that they have had 3 similar cases reported to them in the last few months.
The Australian supplier has walked away from the problem saying that it wasn't applied properly (even though they initially offered to re-supply the products to redo the job)...but without knowing what caused the problem there is no way we're going through the same process again. THis time we're using the Superflite system.
Here's a quote from Kevin Kimball (of Pitts Model 12 fame)
Randolph over then past 6 or 8 yrs has totally changed its formulas due to both regulatory and other issues. They have added so much plasicizer to try and keep the stuff limber, that it never dries. It always stays gummy. After 1 year, you can put a piece of masking tape on it and leave a mark. The stuff balloned loose on one of the gee bee wings after 10 hrs and we recovered it with classic aero which isn't much better. The one cotton and dope job we did came to us with some 1970's randolph dope, the good stuff. It sprays different, smells different, dries different etc, from the later stuff. The old stuff met Mil spec. New does not match mil spec formulas. The pitts factory was having lots of trouble with the dope jobs over ceconite then switched to cotton and found out the the reformulated dope reacted with the reformulated fabric process and the cotton would fail punch test after 3 years. They had to eat 15 or 20 cover jobs. Then they switched back to ceconite and again had adhesion problems like those that Kurt said Stits had. Tapes have left stits jobs but not huge amounts of coatings leaving the bare fabric like dope has. So, then aviat went to the PPG system that has been in existance for nearly 15yrs. No one used it much until Superflight got an STC to use it calling it Superflight system II. So, basically, aviat uses SFsII but buys the stuff direct from a PPG dealer.