I build Warbirds and need to apply Monokote to the top of my wing where it lays in the wing saddle. What is the best method of cleaning the solid surface of balsa on the wing before applying the Monokote? I just need to apply a 6" wide strip on both sides so I can mix epoxy resin and filler to make a perfectly tight fit for the wing. I don't want any gaps. I did this once before but don't remember what I cleaned it with. I was thinking of using 91% alcohol to clean it because it evaporates so quickly. What do you use? I would like to at least get the Monocote on today so any replies will be much appreciated!!!

Barry

Maybe PVA and wax might work better for you. Is the surface painted?

No it is still raw balsa. I am following this method. That one is a 93" Ziroli Corsair and mine is a 126.8" blown up Ziroli Corsair.

Barry

Barry,
Just take a tack cloth to the balsa and remove all the dust. The Monokote shoud stick just fine to the balsa without any additional treatment. I also assume you will be removing the Monokote afterwards?
Later!!
Anthony

Yes then it will be covered with glass cloth and west sytems resin. Primed, details added and painted.

Thanks,

Barry

Barry

Do you want a permanent bond or just a temporary one to form the seat? In any case, brush vacuum the wood to get the dust off. A tack cloth follows. This provides a clean surface. If this is to be a permanent covering, Iwould use balsa rite or unscented hair spray to seal the wood and provide a better bond. A light sanding and again cleaning will be needed as either will raise the grain somewhat.

Nice project you are on. Love to see the photos of your progress.

Don

It would seem to me that a single layer of Monokote is not going to give the same thickness of your glass cloth and west epoxy, plus paint.. Iwould do a couple test pieces to see what the added thickness is going to be for both the Monokote and the west/paint covering. A couple thousandtoo thin of a temp covering when you cast the saddle for the wing could end up with a sizable gap in the center after the final covering is on.

I did a little Rhino work to see what the difference would be. Iused a 4*60 airfoil and offset it by 0.003", approximately the thickness of Monokote. Then I fit it into the original curve with both ends touching. This resulted in a 0.009" Gap at the wides point. This is on a rib of 11.25" length. If you figure that the glass coat with a few coats of paint will probably be in the neighborhood of 0.010" to 0.020" thick, you could end up with a sizable gap, probably around 0.030" to 0.060" given the thickness of glass/paint covering.

Don

I am going to cover the wing in .53 oz or .75 oz cloth and most ofo the primer gets sanded off to a very minimall thickness. Just enough to leave panel lines. I only paint with an airbrush and apply just what is needed to cover everything completely. So what are you saying? I should use multiple coats of covering? I can always cover the wing saddle with glass also. Here is the first layer and I really don't want to apply more. Also if I apply more then the gap would still be the same unless I didn't cover it completely on each end of the cord. The cord is 28". Plus how the heck do I get this off the balsa when I want to remove it. Can I just use a heat gun to melt the glue so it comes right off. Now it is stuck on there it seems for good. I don't want to mess up the already nicely sanded wing. Now you have me confused. The person I am copying is a master builder and he only used one layer and his saddle came out perfect.

Barry

Barry, Using the cord you gave, and finding the thickness of the cloth, and applying a liberal amount of paint, IE total thickness of 0.003", the gap doesn't amount to anything to worry about on a wing that size. The gap becomes fine enough that it isn't important. The shorter the cord though, with the same airfoil and same thickness, the gap becomes more noticeable. I'm guessing yours to be in the noise level, around 0.001" , forget my concern. It wasn't well founded.

As to how to remove the Monokote, as long as it was put on raw balsa, it will peal off cold quite well. Glue joint may cause some minor problems a the adhesive sticks to the glue, or epoxy better than to the wood. Use a single edge razor blade to pick up an edge if it tears.and slowly peal from there. With the overhang shown in the photos, it should be an easy task to simply grab the overhang and pull the covering back. Pealing it rolled back on it's self seems to work best. If the clear surface comes off that what is still stuck to the balsa is the adhesive where all the color is. I've used a heated knife, one of the soldering irons that has an Xacto knife end and use the chisel end blade. Carefully scrape off any color that remains. Be very careful here as it is easy to leave knife tracks in the wood. For that last stubborn bit, Q tips dipped in Acetone will make quick work of them. Don't soak the wood, but wipe the surface quickly. There may be a slight amount of pigment left, but once covered in glass, primed and painted, it will not bother you. Pealing the covering off will leave the wood a little fuzzy and a very fine sanding woud be in order.

I've not had good results using a covering iron or heat gun removing the covering. They liquefy the color and it is as likely to stay on the wood as stay on the plastic surface as you pull the surface off.
Don</p>