Randolph dope

Need to repair ceconite fabric on tail of my experimental. It is done with Randolph dope. What do I need in chemicals to do this repair?
Don,t what to buy stuff I don,t need.

MEK to clean it down to the fabric. Super Seam cement to glue on the patch. Nitrate dope for first coat. Silver butyrate for UV protection. Color dope to cover it up.

Web

Web ,

I a Polyfiber guy but that stuff is on my list plus some reducer. I,m kind of a dope but Why the nitrate dope?

Thanks much,

Don

It's just your base coat. Butyrate doesn't like to stick to artificial fibers but nitrate sticks good. When you cover the bare fabric with the nitrate, it gives the butyrate something to stick to. Kinda like PolyBrush.

Web

Thanks Web. Hey I found the procedure manual online. I revered a flap on my Pacer 40 years ago, but used cotton.

Been a while.

Web

use dacproofer or rando-proofer?, not nitrate... same stuff but with a blue(or green) dye in it...

if its small patch, don't bother... just use the butyrate dope... not much difference...

Some of us regard small patches as minor alterations, and use whatever we want. I have had great success with Poly Fiber or Stewarts patches on just about any covering process including Razorback. I am going to do a small gear leg patch tomorrow with Ceconite on Poly Fiber. Your opinion may vary.

if you need to clean down to the fabric, use clear butyrate dope. it stays in place way better than thinner or keytone. don't try to do too much in one shot. put it on, let it sit, scrape it off with a dullish knife. if you do it right, the curve of the blade will taper the dope from the original paint thickness to bare fabric. that makes blending the patch easier. if you have a long seam or hole that you need to strip, leave about 1/8" along the open part with the dope still on.... that will keep the fabric from fraying while you work the repair.

if you clean all the way down to the fabric, it's best to use the nitrate prime coat (Dacproofer/Randoproof) and then switch to butyrate for the build up. if you bond straight on to the old dope surface you can use clear butyrate to bond with.

I like to pre-dope the fabric & let it dry before cutting the patch (prefer nitrate but buty works too). it makes a really clean cut when you make the patch & the patch is easier to control when you apply it.

since you are experimental, you don't have to follow the rules in part 43 App A. AC 43.13 has some stuff on the process. better yet, look at the Ceconite STC

don d said:

Need to repair ceconite fabric on tail of my experimental. It is done with Randolph dope. What do I need in chemicals to do this repair?
Don,t what to buy stuff I don,t need.

Click to expand...

Duct tape! :smile: Just kidding but it will work. Remember as a rule Butyrate dope goes over Nitrate dope but Nitrate dope doesn't go over Butyrate dope. The Nitrate will lift the Butyrate like paint remover. IF the dope has been on for a long time this may not happen. Both are made by Randolph. Nitrate sticks better than Butyrate. Butyrate shrinks more than Nitrate. Think aileron coves. When Butyrate is used the tapes like to pull during shrinkage over time, rubbing on the leading edge of the aileron. Which Randolph dope is on your plane?

Sky, once I realized the sun usually wrecked my temporary duct tape patch I started covering the duct tape with aluminum tape.

in the old days the butyrate over nitrate rule was because the buty has the higher order of solvent (more active). in the old days nitrate would not dissolve butyrate... but the chemistry changed over the years. you can even use buty thinner in nitrate, where at one time mixing the two would have made cottage cheese (this was demonstrated to me in A&P school over 40 years ago). now you can use either over the top of the other as long as they are clean and dry. there is also no such thing as non-tauntening dope, only "less tauntening".... they all shrink when they dry. easy to prove, put dope in a plastic paint cup and let it dry. the dope film will pull away from the cup..... self cleaning as it were. the thicker the dope, the more it shrinks. same with the old nitrate based Superseam glue. the new SS glue is not a nitrate, it's more like Polytac

Thanks for all the good info...

Depending on the size of the repair, you can also work the patch completely thru the dope just by brushing it with acetone. Then a little dope and sanding and you will hardly be able to see the patch.