I am attempting to cover a foam core balsa sheeted wing. I have sanded the plane to 400 grit, sprayed a 50/50 Balsa Rite and IronX mixture on the plane then lightly sanded with 400 again to get the smoothest surface possible. I am using a cool iron (220 degrees) to apply the Monokote. The Monokote lays down well however after a few minutes bubbles form....a lot of bubbles! I have tried more heat, less heat, gun and iron. It seems as though a gas is forming, hiding in the balsa (because it can't get past the epoxy) and emerging a few minutes later. I thought a cool iron would eliminate the production of gas. Any advice would be appreciated.

Hello,
Get your self a WOODPECKER and before you put the Monokote on,run the Woodpecker along the grain of the balsa.Then lay your Monokote down and heat it with an iron.
NEDYOB

I have covered foam/sheeted wings with monokote.
I didn't have any bubbles form.
Perhaps the solution that you sprayed on your wing has something to do with it.
I haven't found the need for any supplemental adhesive with Monokote. I find that it adheres very well on its own.
The woodpecker mentioned above should allow the air bubbles to escape into the core, however, if you don't have that tool, I would suggest you sand the adhesive off in some area and see if the Monokote will work properly.
Good Luck!

- The IronX you put in the mix may have something to do with it. Its an adhesive remover, its gas may be messing with the monokote.

- When you recover, Seal the root rib, leading and trailing edge, and leave the tip of the wing unsealed to let gasses escape. Use a heatgun and go from the root out, using a wool glove, Tshirt or paper towels to "iron" the covering down. You will get a perfect finish with this method, no bubbles.

The bubbles are because of the smooth wood surface you left. The gasses have nowhere to escape to, you sealed the wood. If you follow this method, you'll have no problem.

A woodpecker would work too...

If you use that delightful woodpecker, how do you iron down the mono and not see all those definite little dimples? If you don't iron it down, just shrink it tight, you still get them around the edges whereever you do iron it down. I would love to use this tool, but find the covering afterward less than satisfactory.

You only see them if you use pearl colors, or transparent colors, Dark colors and sometimes white, you cant see the holes. You will see them if you iron the covering on, but if you heat gun it tight, you probably wont notice. I've gotten to where I can use it, and you wont notice it at all.

Thank you all for your input. I have done some more testing and found the following tricks that helped:

1) Brush (just as the instructions suggest) rather than spraying the 50/50 mixture put enough Balsarite on the surfaces to create a "layer" that allows a stunk adhesion (at 220 degrees which is just before gas bubbles form.)
2) Sand the Balasrite with 320 grit before the Monokote goes on. This creates a "glass smooth" surface.
3) Iron on the Monokote about 15 to 20 minutes after you apply the Balsarite. It dries to touch in about 5 minutes. Don't wait overnight or longer.
3) By thinning the Balsarite you will create a much smoother surface for the Monokote adhesive to grab. Balsarite (out of the can) is pretty thick.
4) Your iron should should not be more than 220 degrees
5) Use an iron rather than gun. You get better temperature control.
6) With Balsarite you get MUCH better adhesion and no bubbles! But if you don't use it correctly.....it sucks.

I use balsa rite all the time for my fully sheeted TF warbirds. I use the "film formula" which is thin, unlike the "fabric formula" which is quite thick.

I never thin it. I brush it on, and sand any imperfections out. I don't use a wood pecker. I use a foam brush to apply it.

I iron monokote directly onto the balsa-rite-coated wood with a relatively hot iron (setting is at 3/4). I iron on from the center out to edges, slowly, stretching as I go.

Often, I balsa rite an entire airplane and don't get around to covering parts of it for weeks thereafter.

I've never had the bubbles problem you are having. I think the problem is the addition of the ironX. It's a solvent, meant to undo many adhesives, and I think it's doing just that, creating pockets of gas as it does so.

Try applying directly from the can, without thinning. I think you'll notice a difference.