Hi all, I recently got my hands on a kit from Japan. Its a Fantasista Evo http://www.ctt.ne.jp/~wcraft/
Its a typical laser cut built up balsa airframe with light carbon parts for the belly and nose section.

my question is what special techniques do you guys have when finishing built up balsa airframes? epoxy or polyurethane varish, and fibreglass cloth? any other threads relating to finishing?

I was going to use basecoat/ clearcoat, and do some trails first. rather than using expensive basecoat colours for the complete airframe, I would try enamel or acrylic paint for smaller areas such as pin strips. the small jars of acrylic paint sold in model shops have a wide range of colours including metallics etc. anyone else tried this? from the Japanese blogs I have seen it appears they use a mixture of paints, let it cure well, then wet sand all ridges smooth and then the final clear coat.

http://f3a.sakura.ne.jp/radiocontrol...dction_31.html this blog is full of information

Anthony

Don Ramsey has a very good video about finishing balsa. In his case it is wings but the same techniques would work on fuselages as well. Here is a link to his site. I have seen the video and it is well worth the money, great detail, filmed well and good narration.

http://suddenlink.net/donramsey/

Woodie

I just finished a Phase One, an older design but I like it and it will do what I need it to do. I used .5 oz. glass cloth on the whole thing with Z-Poxy resin. I brushed on a second coat to fill the weave without adding much weight, then went to work with 240,400 and 600 wet sand paper, lots of work but worth it. I decided to go with Ace brand rattle can paint and used Spraymax gloss clear to top it off and for fuel proofing (using a YS 140 DZ in this one). I'm very happy with the results and have used it on some other airplanes. It's slightly heavier than Moneykote but much more durable and I'll continue using it. I think good finishes just take time and effort.

Rick H.

My technique is the old and proven silkspan and Jap tissue ( Control Line Stunt like) applied with dope. I use nitrate for the bedding of the paper. I currently use light paper but for a guy who has less experience it's better to start with medium grade...much easier to handle. Beware this is an extremely light and thin finish that is prone to some hanger rash....I do everything over a bed of towels.

For paints I use base coat and clear catalyzed urethane over that.

1/2 ouce glass and epoxy or polycryllic works fine but it is quite a bit heavier and possibly a bit more durable. You still have to be careful with handling

On my F3A planes, they are painted balsa, just one coat of light sealer and sanding, then the colour and clear cote, that's it, it has come down to that to keep weight, just make sure the balsa is sanded to a perfect finish, I use 800 grit for final sanding before paint.

The finish is simply perfect. The way you described is perfect, it is a shame Sakura did not built anymore planes, I was told what happened but don't remember....

As you said Anthony, just try it, I used a sealer from Sig, item SL-003, really good, I use Dupont Chroma System, which has a flat base coat and clear, the flat coat dries fast and you need very little paint compared to other Uretane paints, the only thing is do not apply a really loaded coat, just very light coats, even if it takes three or four, weight is minimal, but having to sand and repaint is really something I hate.

Hope it helps

regards

Alejandro

Like Matt, I am having exceptional results with silkspan. I use polycryllic versus dope with two coats of primer sanded almost all the way back. My paint and clear of choice is House of Kolor.

The great thing about silkspan is it looks like it came out of a mold. The problem with glass is sooner or later the weave telegraphs to the surface.

I did the Evolaris on the cover of the June issue of the K-Factor using silkspan.

ok, good ideas here.
what is Polycryllic? is it similar or better than polyurethane.
after some searching last night, I did notice in a Japanese blog, that silk was used, and what looked like polyurethane. that was wet sanded.
that link to Don Ramseys site is a wealth of helpful tips as well. I have used dope and tissue or silk a lot with control lines etc when I was younger.

I have to agree on the silkspan idea, I've done many airplanes that way, it is a great finish. I'm a big fan of dope finishes, doing two Aeromasters in silk/silkspan and dope now.

Rick H.

Here it is:

http://www.minwax.com/wood-products/...tective-finish

Being water based, it has no offensive odor like dope. The down side to water base is it can and will warp surfaces like ailerons There are two ways to deal with this. The first is to coat both sides of the surface at the same time, let them dry until they are not tacky and then weight them. The other is to first use a coat of lacquer based sanding sealer and then the polycrylic.

Polycrylic develps into a thin acrylic polymer. Think plexiglas only extremely thin, on the order of 2-3 thousandths of inch. Minwax and a couple other makers, make a water based paint but you can find other bases as well. This is a tough but a little brittle polymer which isn't really a problem when used with a reinforcing material such as paper, or silk or glass

Polyurethane is urethane based which produces similar thickness to polycrylic. Urethanes tend to be leather tough but are not difficult to sand. Again in the thicknesses we use in models, they all will ding easily.

Epoxy paint used to be my favorite way to finish but it was just too hard to produce light enough finishes. In thin sections it will ding as easily as the others.

Dopes particularly thinned nitrates build into a thinner section than the others. These are also very tough materials but so Thin they tend to require more careful handling. Thin means light so you should judge accordingly. One caution, nitrate dope doesn't hold up great to glow fuel so don't allow soaking for long periods. But gasoline (and electric of course) is fine.

Maybe Isaac has some ideas?

http://www.rcuniverse.com/forum/rc-p...ac-najary.html

Bill P

yeap, I have had a good look at this thread, plenty of good photos
Anthony

I've done a number of non-pattern planes with Polyspan and nitrate, followed by Klasscoat epoxy and maybe Nason clear polyurethane. Polyspan is a good bit stronger than jap tissue and is heat shrinkable.
Just like Matt said, it's a tough, but not-so-light finish.