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Building Tips and technical articles. => Paint and finishing => Topic started by: dave siegler on November 27, 2013, 09:49:54 AM
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My foggy memory seems to think that even nontaugtening dope shrinks a lot.
So if I were to get a gallon of Randolph clear, Which one should I get? I know it will be like maple sirup, and I will need 3 gallons of thinner or so.
Colors come only in tautening right?
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Randolph dope (tautening) clear #9701
Randolph dope (non-tautening) clear W-8350 Has more plasticizer than 9701. Will not continue to tauten.
Randolph colors are non-tautening.
It all tautens to some degree, and is really not that thick, about 50% thinner will get you near a sprayable condition, less needed for brushing. On bare wood you can about take it straight from the can.
See if you can get a Randolph procedures manual and color chart from your supplier, lots of good info there.
Note: The above are all butyrate dope, I used to use nitrate clear #210 for covering and up to the color coats. My latest project has been all butyrate which is what I think most dope finisher do.
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thanks. Wag Aero is just down the road, so I can get anything without shipping as long as I am willing to take a quart or more.
I will get the 9701 and some thinner
And a quart of white.
The old guy at the hobby shop had a 55 gal barrel of Coopers dope, and I would get a pickle jar at a time of it. It was as thick as white glue.
I know to avoid the The "Poly dope" cause is isn't dope, but what is it?
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Be sure you get clear clear, and not that blue tinted nonsense! H^^ Steve
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I use a lot of the Randolphs hi solid nitrate, I do not put paper on with it unless I stop at the first attachment coat, and use water wet silkspan, let that dry then go to butryrate .
The high solid nitrate fills fast, it is also the best thing I have found for sealing the glue side of sheeting that is going on foam
Randy
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The Randolph cleat butyrate you want to buy is A-1690. It is not tinted as the W-8350 is tinted a light tan color. It would be ok for base coats but wouldn't be any good for final clear coating.
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The Randolph cleat butyrate you want to buy is A-1690. It is not tinted as the W-8350 is tinted a light tan color. It would be ok for base coats but wouldn't be any good for final clear coating.
Don't I want the 9701 clear taughtening?
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Dave,
The difference between tautening and non-tautening dopes is small. You can and should use non tautening dope in most all cases. All of Randolph's colors are formulated as non tautening dopes. That just mean that they shrink less than those listed as tautening dopes. I usually use only one or two coats of tautening dope and then as the first couple coats on open bays covered with silkspan or polyspan. The A-1690 is the only clear non tautening clear that Randolph makes, as all the others have tints in them to make them easier to determine film thickness on full sized aircraft covering jobs. If you are going to buy a gallon, get the A-1690 as you can also use it for clear coating after all your color is on.
Alan Resinger
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My previous post was done with a Randolph procedure manual open in front of me. It does not contain the a-1690 product number. ??? I just went out and looked at the gallon can that I am presently using it is A-1690. This is non-tautening clear butyrate dope and I agree with Alan, this is the one you want. I don't know why the A-1690 isn't listed in the manuals I have
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Don,
I think Randolph lists the A-1690 as to be used when covering full sized aircraft with Ceconite. If your manual is for linen covering it lists the other numbers. I wouldn't swear to it but that kinda rings a bell with me. Maybe Bill Byles will chime in.
Alan
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I believe the process for Ceconite is nitrate clear for the first coats, then butyrate clear and color thereafter. "Butyrate dopes WILL NOT STICK TO BARE POLYESTER FABRICS." Quoted from a booklet "How To Cover An Aircraft Using the Classic Aero System. The Randolph manual calls for one coat of G-6302 Rand-O-Proof which is a nitrate base product and inspect to insure complete encapsulation or penetration to the back side of the fabric.
For whatever reason, the Randolph Aircraft Products list just does not have the A-1690 in it nor can I find it anywhere else in the book BUT, it is the butyrate clear to use. A newer copy of the manual may have it, mine are rather old.
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Wag aero has the right stuff. Thanks.
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I believe the process for Ceconite is nitrate clear for the first coats, then butyrate clear and color thereafter. "Butyrate dopes WILL NOT STICK TO BARE POLYESTER FABRICS." Quoted from a booklet "How To Cover An Aircraft Using the Classic Aero System. The Randolph manual calls for one coat of G-6302 Rand-O-Proof which is a nitrate base product and inspect to insure complete encapsulation or penetration to the back side of the fabric.
For whatever reason, the Randolph Aircraft Products list just does not have the A-1690 in it nor can I find it anywhere else in the book BUT, it is the butyrate clear to use. A newer copy of the manual may have it, mine are rather old.
Now you tell me. All of my planes covered with Poly-ester fabric are finished with Butyrate clear dope, SIG and Brodak.
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My previous post was done with a Randolph procedure manual open in front of me. It does not contain the a-1690 product number. ??? I just went out and looked at the gallon can that I am presently using it is A-1690. This is non-tautening clear butyrate dope and I agree with Alan, this is the one you want. I don't know why the A-1690 isn't listed in the manuals I have
If the procedure manual that you are referring to is the Consolidated Aircraft Coatings (PolyFiber) Ceconite manual 101, June 2008 revision, originally issued 1958, the A-1690 non-tautening butyrate clear is specified on page 57, coats 4 through 6. Aircraft Spruce & Specialty Co. shows A-1690 on page 400 of their current catalog and is readily available.
Randolph Products was purchased by Poly-Fiber in Riverside at Flabob airport awhile back and is the manufacturer of Randolph dope products. Hope this was the info you were looking for Don.
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My foggy memory seems to think that even nontaugtening dope shrinks a lot.
So if I were to get a gallon of Randolph clear, Which one should I get? I know it will be like maple sirup, and I will need 3 gallons of thinner or so.
Colors come only in tautening right?
Hi Dave,
Don's reply below your initial post is correct; I would just add that tautening dope will shrink about ten to twelve percent. Non-tautening type dope will shrink about five percent or so; both tautening and non-tautening types will continue to shrink to a lesser degree as the plasticizer leaches out over time.
Just as a suggestion I would suggest that you buy a quart of tautening butyrate (Randolph #9701) to shrink the cover over open bays with first 3 or so coats, and also buy the gallon of non-tautening clear butyrate (Randolph #A-1690) you mentioned for the rest of your finishing. I haven't found that the non-tautening dope will shrink enough to tighten covering over open bays to the degree that I like. As long as you put the lid back on the dope can after each use the dope will keep for a few years.
I think your buying 3 gallons of thinner is a good idea depending on how far you are from an aircraft materials supplier such as Wicks or Aircraft Spruce. Thinner doesn't go bad and I find that I typically use more than I estimate I'll need.