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- This topic has 13 replies, 7 voices, and was last updated 6 years, 11 months ago by Derek McGuckin.
03/26/2016 at 2:06 pm #42464
Awhile ago I covered a Satellite 450 with Polyspan lite. This is the first time I’ve used the lite version. After the usual coats of Nitrate and a few weeks drying time I found the covering to be very brittle and easily punctured. I then sprayed a light coat of epoxy on the stab and it’s still very easily torn.
Aside from using the PSL, is there anything that I missed?
Dan03/26/2016 at 5:03 pm #55884Steve LandyParticipant
I’ve had the same problem with both light and regular. I think I read somewhere that many of these synthetic tissues become brittle when doped.03/26/2016 at 8:44 pm #55885
Huh, never had that embrittlement or any other trouble with regular polyspan. Have covered F1As & E36s, then nitrate doped a coat or two.
The covering held up quite will covering wise.
Never used the lightweight stuff. Comments from others said it was difficult to close its pores with dope, so I avoided it.03/27/2016 at 2:03 am #55886Scott LapraikParticipant
Dan, I’ve tried Polyspan lite a no. of times and it just doesn’t stack up to regular Polyspan. The brittleness your talking about is more likely due to the P.S. lite. It isn’t near as tough as regular P.S. I’ve only used it on stabs and have popped holes in it when attaching the rubber bands. So what I did to resolve this was to add another layer with the grain 90 degrees to the initial application. This was in the ctr. section only! I use regular P.S. on all my Nos. planes where the wing structure is not stiff enough for plastic covering IMHO! Works great too!
Scott03/28/2016 at 5:55 pm #55887
Thanks for the replies guys…
I’ll nix the lite stuff and stay with the original. I thought perhaps Butyrate dope might be better but I’m not sure it’s compatible with epoxy finishes.03/29/2016 at 10:55 am #55888Scott LapraikParticipant
Dan, epoxy over Butyrate dope is not a problem. I’ve been doing it for years!
Scott04/03/2016 at 2:35 pm #55883GeneChristensenParticipant
Put a drop of caster oil in the dope it will rubberize it, and make it less brittle with no ill effects to the finish.04/04/2016 at 5:44 pm #55882
Hal Cover recommended TCP(Tri Cresyl Phosphate)as a better plasticizer additive. Been using it since 60s or thereabouts.
Non-tautening dope may be an equiv.
It’s available in pints/quarts, etc, from Aerodyne, or Aircraft Spruce in larger sizes.04/04/2016 at 6:19 pm #55881Mike SchwartzParticipant
Lee is correct. We have been using TCP as a plasticizer since 1959.
Mike04/06/2016 at 2:03 am #55878
Approximately how many drops TCP per quart dope?
Thanks!04/06/2016 at 2:46 am #55879
Wow, can’t recall how much I used per volume. Maybe Mike will know.
It did not seem very critical as I recall.
Maybe 3-6 drops per ounce?
Anybody?04/06/2016 at 7:51 am #55880Mike SchwartzParticipant
The amount of TCP used is not critical. 3 drops per ounce is all that’s needed. if you get a couple extra drops, its no big deal. Use a small glass or plastic eye dropper to add the TCP to dope. Add it to the thinned dope and stir it in completely. You can use it in either nitrate or butyrate dopes.
Mike04/21/2016 at 4:41 am #73971GeneChristensenParticipant
Polyspan lite over tissue is very stiff04/21/2016 at 10:04 am #73986Derek McGuckinParticipant
Gene, any specific reason you put the polyspan over the tissue? I have thought of using tissue over lite polyspan. I like the look of tissue.
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