SilkSpan

[Darrell Mims]

  How do you tell if silkspan has gone bad? does it have a shelf life? I have tried to patch a hole in my Oriental wing several times and the edges will tear at the rib caps. Iv'e had to double and tripple the layers.

[Mike Spiess]

Sounds to me like you sanded to close or on the rib caps. My experience silkspan doesn't age the finish you put on does though. Nitrate will "evaporate over the years if not covered. and butyrate becomes brittle and shrinks as seen by the cracks that are present in old dope finishes.

[Tom Perry]

Silkspan does have a bad habit of absorbing oil in the air, moisture, dirt, etc. It can get very brittle if left in a hot place such as an attic, even if in a kit. I have some like that. If the silkspan is a dark yellow to light brown or darker, it is brittle and frankly no good. Toss it. I did mine. 

Ty is exactly right.  After a 30+ year sojourn I returned to modeling and discovered this to be to true.  my problem was only some of it was bad. the problem is you can't tell just by looking.

I built 5 models and covered with the old stuff.  3 turned out ok but 2 were so fragile that just holding them on an open bay would end up with a digit penetrating the wing.  Best to toss it and get some new.

[dennis lipsett]

I have quite a bit of the old stuff and always kept it in the box that it came in and in a cool dry dark place, wrapped in plastic wrap.. Suprisingly it is all good and I've been using it. I also bought off the bay a few complete boxes of K&S silkspan and it was also good. This was also old stock and had not yellowed or darkened so it had to have been well taken care of. My biggest problem is that I have lots of the 00 and gm but very little of the gms paper, so I've not used it on my larger planes. Instead I use polyspan which is really much more durable.
dennis

[Bill Little]

I use all the "old" stuff that is suspicious on fuselages and such, not over open areas.  No problem when doing that!

Bill <><

[Bill Little]

Good idea Bill. Waste not, want not.

Hi Ty,

I'm pretty sure we grew up in very similar environments.

A touch of "plasticiser" (castor oil) in the clear, and the old stuff is just fine over sheeted areas.

Bill <><