After many years away, I have once again built a Ringmaster to be  powered by my old trusty Fox .29. Last Ringmaster I had was about 1960 when I was 14.  After talking to some fliers at a local control line field and reading about new stuff on the internet I made the decision to cover wings with polyspan.  Trying to follow all suggestions I could find, the covering job went well with only some minor trouble at tips. I've got three coats of butyrate dope, thinned , and see some trouble area that are not filling in open bays.  Those areas, especial ONE, look like the fibers of the covering are just not well distributed, actually all along a span-wise band but most obvious in that one spot.  I don't think I had to use very much heat in shrinking with my iron and tried to just float it quickly over the surface when all was attached.  I found out near the tips that holding the heat too long in one spot and pulling can easily separate the polyspan, at least across the width.

When I look at the remaining material left over from covering, I see that fibers are not very well distributed across the width. Is it normal with this material to spread it out and choose what portion to actually use, trying to eliminate parts of the roll that "might" cause trouble? I ordered regular weight but wondered if it is right.  I cant say about weight but thickness is .0022" to .0025".  When I remember what I can about silkspan, and compare polyspan to some tissue and some old micafilm piece that I have, the distribution of fibers looks very irregular on the covering I just used.

Can anyone comment?  Right now I intend to dope a patch over that one problem area and continue with finishing.

I've never noticed that fiber strands like that on all the Poly-Span I've used.   But, like you said if you use a heat gun and hold it in one place too long, it means making a patch.  Yes the tips take time an heat as well as patience.  but, I don't think you can see the spots where I had wrinkles plus patches once all the coloris on.

I may go back to silk on my next model.  My local hobby shop, Hobby Barn in Tucson, actually has some Sig silk in two different weights.  I thought on this Ringmaster I'd try to save some weight and be a little more modern. I think I would have used silkspan if it had been a little more readily available.  Maybe I did not look far enough. An old flying buddy I went to school with offered me some but I  guess I just wanted to give polyspan a whirl since I'd heard how strong it was. As it is, I'm not convinced of strength.  I'll see how the Ringmaster holds up.

I have some of what I think is the Starline brand of polyspan.  It is very consistent in density, no obvious spots where the material looks "a bit thin."  And, it is fairly easy to determine which side is up and which is down.  There is a difference in sheen and feel on each side.  This product has always worked out pretty well for me.

But, I bought a roll of what might be a polyspan clone.  No labeling as to who made it.  It is not very good.  There are obvious thin spots.  More like voids that don't look like they would ever fill properly.  It is almost impossible to determine which side is supposed to be up and which is to be down.  I have not tried using this particular polyspan yet.  I have a scrap wing and will try it there first before I took a chance on a good wing.

If I get anymore polyspan I will stay with the Starline.

I got my Polyspan from Larry Davidson: http://www.modelflight.com/larrydavidson.html

I recently ordered several pkgs of Brodak "silkspan".  I thought it would be that light, flimsy stuff.  But it looked to be medium-heavy.  I used it right away with great results.

Brodak part nr. BH 926.  Package contains two sheets 24" X 36"  (no price on the pkg, and I don't remember how much)

Floyd