Painting and smoothing foam electric airplanes
07-22-2005, 11:24 AM
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Painting and smoothing foam electric airplanes
I'm trying to paint a few foam airplanes, but they are not smooth. What can I use as a filler that would stick to foam, and not weight down the plane. I've heard Drywall compound, and urenthene. Any suggestions? What is the prep process?
07-22-2005, 02:48 PM
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RE: Painting and smoothing foam electric airplanes
It's nice to be able to prevent the foam from accumulating dirt just from handling (let alone landing!) but I had to admit that I just cannot expect a finish on a foam airplane to rival a fiberglass job with auto paints so if you try to be too fussy you will end up frustrated. Do not expect to completely eliminate the beaded appearance of the foam but you can reduce its prominence.
(If you DO want to glass the foam part, then you can get a very nice finish.)
That said, here are some pointers from my experience.
Zinsser B-I-N primer-sealer-stain killer in a spray can from the hardware store will not attack foam and dries enough to sand in 15 minutes unless it's put on too thick or if it's brushed. I've seen it at Wal-Mart too.
I repaired deeper dings with vinyl spackle and sanded with 220 dry. Then I sprayed the primer and sanded with 320 or 400 wet. I just used a pie plate half full of water and kept dipping the wet-or-dry paper into it. I rinsed the slurry off the part. I used Testor's spray enamels over it. Enamels are not fast drying paints, tho. Both the spackle and the primer dry fast so you can get thru many iterations of surface preparation in a short time even if you later have to wait longer for the colors to dry.
The one problem I had was that masking tape tended to pull it up in spots along with the masked color on top of the primer. Even low tack tape would sometimes do this. Apparently the bond between the primer and the foam is not terribly strong. I filled the spots in with vinyl spackle, sanded, re-primed and resprayed and eventually got to a presentable job but this greatly extended the time it took to do the job.
If you are spraying only one color and don't need to mask you'll be fine. If you do need to mask try to be very careful both applying and removing the tape. When putting it on, try to limit the burnishing down of the tape to a small width near the edge of the mask instead of the entire width of the tape and when removing pull the tape back on itself, not up 90 degrees to the surface. Use a steady slower pull to give the adhesive a better chance to release and if you see it start to pull the paint/primer up, stop immediately before it pulls up more and see if you can tease the tape apart from the paint with the point of a knife blade, to at least limit the damaged area. I tried pulling the tape starting again at the other end so it would tend to lay the loose part down instead of pulling it up more but I only got another lifted spot coming the other way.
I have yet to find any kind of paint, surface prep or iron-on film or fabric that did not give me some kind of difficulty in finishing an airplane but I can't stop trying and I do gradually get better.
I hope you find some of this helpful.
Tom
(If you DO want to glass the foam part, then you can get a very nice finish.)
That said, here are some pointers from my experience.
Zinsser B-I-N primer-sealer-stain killer in a spray can from the hardware store will not attack foam and dries enough to sand in 15 minutes unless it's put on too thick or if it's brushed. I've seen it at Wal-Mart too.
I repaired deeper dings with vinyl spackle and sanded with 220 dry. Then I sprayed the primer and sanded with 320 or 400 wet. I just used a pie plate half full of water and kept dipping the wet-or-dry paper into it. I rinsed the slurry off the part. I used Testor's spray enamels over it. Enamels are not fast drying paints, tho. Both the spackle and the primer dry fast so you can get thru many iterations of surface preparation in a short time even if you later have to wait longer for the colors to dry.
The one problem I had was that masking tape tended to pull it up in spots along with the masked color on top of the primer. Even low tack tape would sometimes do this. Apparently the bond between the primer and the foam is not terribly strong. I filled the spots in with vinyl spackle, sanded, re-primed and resprayed and eventually got to a presentable job but this greatly extended the time it took to do the job.
If you are spraying only one color and don't need to mask you'll be fine. If you do need to mask try to be very careful both applying and removing the tape. When putting it on, try to limit the burnishing down of the tape to a small width near the edge of the mask instead of the entire width of the tape and when removing pull the tape back on itself, not up 90 degrees to the surface. Use a steady slower pull to give the adhesive a better chance to release and if you see it start to pull the paint/primer up, stop immediately before it pulls up more and see if you can tease the tape apart from the paint with the point of a knife blade, to at least limit the damaged area. I tried pulling the tape starting again at the other end so it would tend to lay the loose part down instead of pulling it up more but I only got another lifted spot coming the other way.
I have yet to find any kind of paint, surface prep or iron-on film or fabric that did not give me some kind of difficulty in finishing an airplane but I can't stop trying and I do gradually get better.
I hope you find some of this helpful.
Tom
