Estes EAC VIPER #0820, BT-55 Upscale, Part 6, Step 1 - Filling Seams & Balsa Grain

I see forum posts about a builder doing six or seven spray and sanding of filler/primer to fill the balsa and tube seams. It shouldn't be that difficult.

I do a two-step process that fills the grain and tube seams. 

Thin out Elmer's Carpenter's Wood Filler with water. For more info: CLICK HERE

Here's STEP 1:

Brush on one side and let dry. Don't panic if the balsa warps! 

Brush with the grain first. Then while the filler is still wet, brush against the grain to force the filler into the pores.

The balsa will level out when the other side gets it's coat of CWF.

On the left is the balsa after the CWF dries. It will dry with noticeable brush strokes.

I first sand with 220 grit to remove the brush strokes (take off just the top) then 400 grit to do final smoothing.

Don't sand all the way through the CWF, leave a very thin beige layer. If you see the pinkish balsa you've sanded too far. 

For the tube seams:

Dip just the tip of an old knife blade in the thinned CWF. Wipe the backside of the blade off over the lip of your thinned CWF container. You won't need the CWF on the back of the blade.

Set the blade in the tube seam and move it back and forth. This should leave CWF in the seam. The blade directs the filler into the bottom of the gap. You should be able to fill an inch or so before dipping again. 

Dip, wipe off the back of the knife and apply the next inch.

I remover the bulk of the seam filler using 220 grit on a sanding block. I haven' t taken the filler down entirely yet.

Follow with 400 grit to take the filler down to the tube surface.

This will leave the tube a bit fuzzy. The fuzzy surface will be gone after the next step.

The second filler step using a spray of filler/primer is next.