malmaz Posted October 25, 2019 Share Posted October 25, 2019 I am building a Curare from a plan using foam cored wings and tailplane, I am thinking of glassing it using Poly C or deluxe Eazy Kote. My question is, what do you use to seal the wings and tailplane other than sanding sealer due to it seeping into the foam,? Thanks Quote Link to comment Share on other sites More sharing options...
Richard Wood Posted October 25, 2019 Share Posted October 25, 2019 I've used Ronseal type varnish before with success as an alternative to sanding sealer when the sanding sealer had run out. I've not yet had a problem with sanding sealer on foam wings as long as it isn't thinned... Try it on a small area or scrap experimental piece 1st. Edited By Richard Wood on 25/10/2019 09:35:04 Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 25, 2019 Share Posted October 25, 2019 Why can't you use Poly C, or Eazy Kote. Aren't they basically the same stuff as Ronseal. Quote Link to comment Share on other sites More sharing options...
Richard Wood Posted October 25, 2019 Share Posted October 25, 2019 Posted by Don Fry on 25/10/2019 09:42:16: Why can't you use Poly C, or Eazy Kote. Aren't they basically the same stuff as Ronseal. They're water based & if applied straight to the veneer will ripple it. The Ronseal used was not the water based type. Edited By Richard Wood on 25/10/2019 09:50:07 Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 25, 2019 Share Posted October 25, 2019 Thank you Richard. Quote Link to comment Share on other sites More sharing options...
malmaz Posted October 25, 2019 Author Share Posted October 25, 2019 Don Fry So you think I should give the sanding sealer a try ? I am certain I have used dope/sanding sealer in the past on foam cored wings when I used to tissue cover them before painting and did not have any problems, so I think I might give it a go Quote Link to comment Share on other sites More sharing options...
ron evans Posted October 25, 2019 Share Posted October 25, 2019 I've recently mended a veneered foam wing with light glass cloth and Wilco water based poly. There seemed to be no adverse effect on the veneer after 3 coats. Many moons ago I finished a foam wing with tissue and dope, and the dope seeped through the wing tip joint to eat away some of the foam, a bit of a mess to sort out. Quote Link to comment Share on other sites More sharing options...
Bruce Collinson Posted October 25, 2019 Share Posted October 25, 2019 Didn’t I read that Poly C is not advised for glassing, and that water based resins will tend to cause adverse effects to veneer? Why not epoxy resin which doesn’t eat foam? Z Poxy seems to have its detractors but I’ve got on fine with it. BTC Quote Link to comment Share on other sites More sharing options...
ron evans Posted October 25, 2019 Share Posted October 25, 2019 Can't see why water based poly shouldn't be used on veneer, it is made for use on wood. Both my Cutlass airframes are glassed with poly over wood, depron and epp (see my photos) without any issues. Epoxy does give a harder finish, but poly is completely adequate, with a low odor and easier clean up. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted October 25, 2019 Share Posted October 25, 2019 Posted by malmaz on 25/10/2019 11:58:02: Don Fry So you think I should give the sanding sealer a try ? I am certain I have used dope/sanding sealer in the past on foam cored wings when I used to tissue cover them before painting and did not have any problems, so I think I might give it a go Sorry, I didn't say that. Havn't owned a pot of sanding sealer for many years. My post assumed that Poly C et al, were the same as Ronseal. All waterbased. I personally would not use water on a veneer, it swells the wood, when you think about it, and that can't be good. I was curious. My system is, I use epoxy. I use no other, and was curious about other systems. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted October 25, 2019 Share Posted October 25, 2019 The veneered foam wings and fuselage decks on my La7 were fine with water diluted PVA and brown paper, and back when I built my Eros I covered the 1/16" sheeted fuselage with 20gm glass and PolyC, again with no issues. If you think about it, the low viscosity epoxies used for glassing also soak into the grain and cause swelling, try coating one side of a sheet of thin balsa and you will see it curl over. Maybe not quite as much as a good soak in water but then Poly-C also has a higher viscosity than water too. I seem to remember back in the mists of time when I covered foam wings with tissue and dope I put the tissue on wet. IIRC I sealed any seams and cracks in the veneer by rubbing in PVA. edit - all this assumes that the veneers are tightly attached to the foam! Edited By Bob Cotsford on 25/10/2019 19:53:05 Quote Link to comment Share on other sites More sharing options...
PatMc Posted October 25, 2019 Share Posted October 25, 2019 If there's a risk that cellulose based sanding sealer will find it's way through to the foam core then the same danger is present with Ronseal varnish which is also based on an EP foam solvent. Like Richard, I've also used doped tissue & sanding sealer on veneered foam wings without any problems. I've used Wilko's water based varnish & Rustin's water based floor varnish on tissue covered balsa sheeted wings (but never on obeche veneer) again with no issues. Edited By PatMc on 25/10/2019 19:58:02 Quote Link to comment Share on other sites More sharing options...
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