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Building Tips and technical articles. => Paint and finishing => Topic started by: fred cesquim on June 24, 2022, 05:28:04 AM
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fellows this is my third endeavour with polyspan
some rips started to develop while sanding the primer ( light hand, belive me) ;D
i fized and shot yellow
probably this rip was while masking colors and moving around
is that normal with polyspan, that fragility or am i doing something wrong ( other than hitting the covering with things)
any advices or tips?
thanks
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Have you been using the same polyspan all along? That is, the same brand. I have encountered some polyspan clones. These clones are not of the same quality as the original polyspan. When I started using polyspan, it was the Starline brand.
Most of the clones were poor quality. I have no idea who made them as there was no labeling. The product was wrapped around some cardboard with no manufacturer information. The weave was quite coarse in spots, very uneven, and there was no way to fill it with dope or anything else. And, with such large voids, it was rather fragile, tearing easily.
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Have you been using the same polyspan all along? That is, the same brand. I have encountered some polyspan clones. These clones are not of the same quality as the original polyspan. When I started using polyspan, it was the Starline brand.
Most of the clones were poor quality. I have no idea who made them as there was no labeling. The product was wrapped around some cardboard with no manufacturer information. The weave was quite coarse in spots, very uneven, and there was no way to fill it with dope or anything else. And, with such large voids, it was rather fragile, tearing easily.
bought them from RSM all looks the same, good weave overall. maybe i am not doping enought? 6 brushed coats 50% dilluted, not butyrate
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Sounds to me not enough clear before the primer coat. My self I put enough clear that it starts to get a sheen to the surface. Then I put on the base primer and least two coats before sanding. Takes very little sanding as my poly-span looks decent when I put on the color coats. After all the graphics I shoot a coat of clear. Really I sand primer coats only where the area is still showing pin holes or rough to the feel. Take a very light touch with 200 grit paper. D>K
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Fred, I have used polyspan (from Okie) for years and never had a crack. Sanded through some rib edges but even then it frayed but did not crack. That spiderweb tells me that the dope was really brittle. I agree, bad lot.
Ken
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so probably i was conservative on the doping and ended up being fragile, well, hope the clear coat will stiffen and holds the finish
next time will ad more dope layers.
thanks for the input guys!
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I'd like to know what kind of primer you used.
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I'd like to know what kind of primer you used.
sherwin williams spektra prime, 2 part Polyurethane ( it comes with some plasticise to be applyed on plastic bumpers and be less brittle)
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I still think the problem is low quality poly span. Unless you got some labeled Starline, it could be a clone. There is no way to know who made it. It might look OK but it is not of equal quality as Starline.
Some years ago, there was a product called Thermal Span. Same material as poly span, and attached and filled the same way, but it was as strong in the chord wise direction as it was span wise. There was no "grain." The weave looked tighter and I preferred it to poly span. You might still be able to find it but with so little demand these days for such things, it is probably out of production.
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I'm just getting back into the hobby now that I'm retired, so I need to know where's the best place to buy: Polyspan, Dope, and Thinner. FYI, I'm frustrated with iron-on coverings that can't take the Florida heat while being left in a closed up car for a few minutes. For instance, I have a plane with an UltraCote covering and the covering shrinks even more in the car and then wrinkles after it cools. Since I seem to be able to keep my airplanes for 10 years or more I'd like to learn how to apply a longer lasting covering, no mater how long it takes to apply. BTW, I watched a video on the Stunthanger YouTube channel and a guy there did a wonderful job explaining how to apply Polyspan. I just need to learn where to get the materials from.
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Dope and thinner you can get from Sig Manufacturing, polyspan from Okie Air.
Motorman 8)