I'm beginning the finishing stage of my winter project; a Sig Super Chipmonk that I plan on flying at the Northwest Regionals in Eugene in May. My question, how long should I wait between coats of dope? I brushed on the first coat over the airframe yesterday (the bays are still open) and plan on sanding today. Will it be ok to brush on the second coat today? I plan on entering the plane for appearance points, but I'm not looking for, or planning on, a 20 point plane; if I can garner 10-15 that will be fine. I'm brushing on Randolphs non-tautning nitrate for the base, and will switch to Randolph's Butyrate when I put the silk on the bays. I've thinned the nitrate about 50%, is that enough? Too much?

Thanks,

Brian

Thanks Randy; I will take your advice every time. 

I sanded the first coat with #200 grit sand paper and was happy with the finish. I then applied a second coat, and after drying and with no sanding a third coat. I am now seeing lifting of the dope in the wing/fuse joints, causing bubbles at that point.

What am I doing wrong?  I'm not too concerned with this plane; I know I'm still learning, but would like to avoid this issue in the future if possible. Am I not thinning the dope enough, applying the dope to thick, or the second coat too soon? Or . . .  .

I'll sand this out tomorrow, but before I do I will take some photos and post. For me this is a huge learning experience and I would like to learn sooner than later.

I'll sand again with #200, then with #500; at that point I hope to switch to Butyrate and get ready for the silk.

I'm planning on using the Randolph's white (butyrate) I ordered as both a primer and base color. I'll be thinning quite a bit (60% thinner or more) and brushing the white. I hope it will flow well then. I'll be sanding between coats before going to color and a final clear coat. The last two stages I hope to spray.

Any thoughts, comments, suggestions . . . or laughs are welcome.

Brian

Hi again Randy; The fillets are balsa and glued in place (Sigment). I used Hobbylite balsa colored filler to fill in gaps. I sanded that down, cleaned only by blowing hard and wiping with a rag; then the dope.

As I said, I'm not too concerned with this plane, but really want to learn to get the process right.

Here are a few pics.

Brian

Brian,
If I were you I'd get rid of the Hobbylite before you go any further.  That stuff is almost a guarentee of lifting in a filleted area.  I wouldn't use it anywhere.  Get some Epoxolite, Aeropoxy Light or some Polyfiber Superfill.  Make sure when you use Randolph butyrate that you add some plastciser to keep it flexible.  Go easy on all dope applications in the fillet area and it helps if you can spray those areas with a somewhat dry spray.  With brushing you have to lay it on very thin and get away and let it dry.  Also when brushing a finish, I'd probably thin more like 70% thinner to 30% dope.  That way the dope will level out better.
Alan Resinger

Thanks Guys! I really appreciate your help. I won't strip it off this ship, but will switch to something else for the next one.

Brian