Painting directly on the wood or Covering?

[Tony H]

Hi All,

I was chatting to a fairly experienced guy at our flying site regarding painting ic aircraft insteady of covering.

He says if you have a fully wood covered/sheeted aircraft you can just sand it smooth, fill it wth yellow car filler, sand it smooth again then use sanding sealer then spray paint it with car spray paint.

Is this a good idea? will this be too heavy? will the paint come off with the fuel when you wipe it down ( he says it won't)

Any thoughts? Should I just cover it with solarfilm?

[Peter Miller]

Painting on bare balsa is not a good idea, the wood will eventially sag and or crack. Also coveirng with tissue adds strength to the wood.

The tissue prevents the eventual sinking of the finish into the grain. This may take months or years but it will happen.

You don't need car fillers which do tend to be heavier. Sanding sealer works well but you can also use dope with talcum powder in it for the first coat.

It is possible to achieve a finish like glass with dope and tissue, sanding sealer and then paint , all rubbed down between coats.

My sequence used to be, Dope and talc, tissue and dope, then three or four coats of sanding sealer and finally two or three coats of celullose paint. It is very important to let the various coats dry completely before adding the next.

Another secret of a perfect finsish. It isn't what you put on, it is how much you sand off.

[BB]

Depends on the size of the model. Chris Foss advocates glass clothing his planes (kit built not the newly introduced ARTF variety) then painting/covering.

BB

[Ernie]

Hi Tony, Not a good idea for two reasons. 1 The untreated wood, especially balsa will soak up the paint and you'll need zillions of coats to get a good finish. 2 A covering of tissue, or nylon, or very light glass cloth will give a increase in strength, a resistance to hanger rash, and provide an excellent base for paint

ernie

[Martin Harris - Moderator]

There's a strong likelihood of the finish developing cracks along the wood grain if you don't cover it with a stable layer such as glass cloth and epoxy/WBV or the traditional doped nylon or tissue.

2 pack car paint might be fuel proof but is extremely dangerous to spray with "home" protective equipment and cellulose or modern equivalents aren't fuel proof in my experience - even a metallic lacquer that I tried wasn't. You can always test a sample if you want to be sure.

[Peter Miller]

I should have added that the final coat should be Tufcote or Aerocote as these fuel proofers can be buffed to a glass like finish.

My finish as described takes a very long time, is very smelly and is hard to repair but, Boy!, Does the finished result look good.

Edited By Peter Miller on 13/03/2012 08:49:43

Edited By Peter Miller on 13/03/2012 08:52:11

[Richard Wood]

As Peter says, you can get an extremely smooth, almost glass-like

finish with traditional tissue & dope by careful rubbing down. You could also

consider using Poly-C instead of dope as it's a lot less smelly - but possibly

not quite as hardwearing.

If using Poly-C apply 8 or so thin coats with a light fine sanding between coats.

It takes around 1/2 hr to 1 hour to dry depending on temp. & humidity.

After this use very fine wet & dry paper wet with warm slightly soapy water to

achieve a very flat glass-like finish with no brush marks, runs or 'bits' left

prior to priming & painting. Be careful not to remove too much Poly-C

when rubbing down.

It's a very satisfying process & can produce a very good finish.

 

 

 

 

 

Edited By Richard Wood on 13/03/2012 09:01:09

[Engine Doctor]

I have used brown parcel paper fixed with pva for prepping balsa covered areas for paint . The last model I used it on was a1/5 scale  DB Hurricane . The wings and fus ,from the cockpit forward were covered in it . Its very strong .It can be used in small sections overlaped to replicate panels and paints really well and its cheap . total cost for huuri was about £3 .To cover the Hurri in tex or glass would have cost a fortune and the glass epoxy would have taken forever. Obviously no good for small models where weight would be a problem but bigger models its fine.Balsa sheet needs a coat of dope prior to covering to stop it buckling with the moisture from the pva .

http://twokentvillages.org/assets/mmfcforum/view_topic.php?id=127&forum_id=11&page=4

Pics of brown paper covering on my building blog of DB Hurricane

Edited By Engine Doctor on 11/04/2012 17:39:43

[Reno Racer]

I've had good success painting over film coverings. This will be far lighter than using all that filler or glass cloth.

Just rub down the film with scotchbrite to key the film so that the paint sticks and spray on. Use a fuel proof laquer to seal the paint and any decals. Using this method, I've never had an issue and the film doesn't seem to sag in sunlight etc after spraying. If you use silver film, you can rub the paint back to add some weathering effect.

Corsair was sprayed using this method.

Chris

[Ben B]

Nice Corsair. Very tidy. I really must try spraying films at some point. My brain says it won't work but lots of people who have tried it say it does!