Materials overview

Before covering my glassing techniques used on this project, let me first review the materials I used. These will be the same ones as were used on my last scale project, the SBD Dauntless.

First off is Deft Sanding Sealer. This Lacquer based product is easily brushed on right out of the can and acts as a sealing barrier to help keep the waterbased Poly from soaking into the balsa. This reduces weight and warping, especially on built-up constructions (warping isn't really an issue on foam builds like this one).

Two quick coats and a good smooth sanding gets your airframe ready for glassing. You'll find the surface to be much harder and smoother after sealing with the Deft Lacquer, which also helps the glass cloth to lay down better. The Deft dries in about 15 minutes or so.

Next are the actual glassing materials. At the core of this list is your fiberglass cloth... I use 3/4 ounce cloth exclusively. The cloth needs to be applied with some sort of "resin" which can be one of any number of materials (Epoxy, Polycrylic, Lacquer, Polyester, etc).

My preference is Minwax waterbased PolyCrylic (satin finish). In my experience it is less expensive, goes on faster and easier, no mixing, no mess and virtually no odor. All clean up can be done with water and you can apply it with a brush or roller. I prefer to use a 2 inch nylon brush to apply it straight out of the can.

Glassing the wing

Starting with the wing, I flip it over and work the bottom side first. I cut a piece of 3/4 oz cloth that is big enough to cover the entire bottom in one piece. I leave plenty of excess around the edges... about 4-6 inches is plenty.

Starting from the center, I brush on the Minwax Poly towards the LE and TE of the wing root, then work my way out towards each wing tip. As I work out towards each tip, I continue to work form the center forward and backward towards the LE and TE along the way. I apply it clear around the LE of the wing, almost to the top side of it.

It takes anywhere from 20-40 minutes for it to dry, depending on temperature and humidity. Don't accelerate the drying, you want it to settle down into the cloth and level out. Once it is dry, I hit it with another coat and let it dry. These first two coats will properly secure the cloth in place well enough to allow you to go around the edges and remove the excess trim.

I generally use a hobby knife to cut the excess away, then use a sanding block to feather the edge of the cloth in just a bit. Don't go overboard or you'll sand the surrounding balsa away. Once you've minimized the cloth edging, you can flip it over and start on the top side.

I repeat the same process on the top side, giving me about 1 inch of overlap at the edges of the wing. Again, two coats dried on the top will secure it and get it ready for more sanding. This time, let it dry just a bit longer, then go ahead and try to feather the edge overlaps out. It won't take too much work, the 3/4 oz cloth and Minwax tend to just melt out of sight anyway. You don't need to get it perfect yet, there are more coats to follow.

The thing about waterbased Poly is that it has so much water content that once it dries and the moisture evaporates out, you're left with a VERY thin layer of Polycrylic. Therefore it takes about six coats to adequately fill the weave of the glass cloth. It's no big deal since it goes on so fast and dries so fast. It takes no time at all to hit six coats.

After the third coat is when I start to get a little more serious with my sanding. You still have to be careful though as it is easy to cut into the cloth. You're really just trying to get the excess buildup, runs and seams knocked down at this time. If you like, you can sand again after each subsequent coat, but I didn't. I sanded after the third coat, sanded very lightly after the fifth coat, then sanded thoroughly when the sixth coat was dry. Actually, you could probably get by fine by sanding only after the third and sixth coat if your really wanted to.

You'll know when you've filled the weave good enough by the "sound of the sand." When sanding the surface, you'll hear a "zipper-like" sound as the sandpaper crosses the brittle weave of the cloth. Once you have the weave filled with Poly, the zipper sound will go away and it will be the same quite hush you heard when sanding the bare balsa.

Control surfaces and canopy

Ditto on glassing technique for the control surfaces except for a couple minor differences. First, I only put four coats of Poly on the control surfaces. I actually put it down a little heavier, but not much. But, I'll be adding another coat or two later after doing some additional detailing work (I'll explain later).

The other difference is the "inside" of the flaps. Due to all the ribs, hinge blocks and horn blocks, you just can't lay cloth down in there. So, I just hit that side with about 3-4 coats of Deft Clear Lacquer Wood Finish from a spray can. The flaps are not balsa, so they're pretty stiff and strong anyway. You really just want to add a smooth surface to make painting easier.

So, a few coats of Clear Lacquer and a little sanding and you're done with the inside of the flaps (likewise for the flap bays in the wing). The "outside" of the flaps get glassed with Poly and cloth just like the rest of the plane.

As for the canopy rear (sliding) section, I use the same glassing technique here as well. I cut the cloth just short of the open glass area. I don't glass the underside, I just put about 3 coats of Poly directly on the thin AC ply so I can sand and paint it. After all the poly is applied, dried and sanded, I'll begin masking off all the open glass areas with masking tape before moving on to the primer and putty stage.