Quest Striker AGM Build Part 7 Filling Tips

On most models, I've been filling the balsa grain before gluing fins onto the body tube. This is for a few good reasons:
Trying to fill balsa (using sanding sealer or CWF) near a glue fillet at the root edge never gets good results.
It's easier to fill a flat fin surface when it's off the body tube.

TIP: You'll get a stronger root edge glue bond using the Carpenter's Wood Filler opposed to sanding sealer) if you choose to fill balsa fins before gluing to the body tube.
CWF is water based. Any white or yellow glue adheres better to a water based filler. Sanding Sealer or Balsa Fillercoat will seal the wood and not allow glue into the wood surface when adding fillets. Some builders still prefer sealer and fillercoat to fill balsa.

Look at the lower half of the Striker fin root edge.
The flat balsa surface (facing away) has one dried coat of CWF.

Look close and you'll see the curved warp down the root edge.
The side of the fin you can see has yet to be painted with CWF.
When the second side dries, the new filler will straighten out the curve.

Contrary to what I've read on the rocket forums, most thin balsa will warp using a sanding sealer or CWF. I've used sanding sealer off and on since 1969 and it pulls and warps as it dries. I was told by an experienced model plane builder that dope finishes will keep curing and tightening for years. (I don't know it that is true or not.)
When you fill the other side the bend should go away without laying waxed paper and weights on it while drying.

Again off the model, the launch lug gets the seams filled with CWF.

When filling body tube seams, CWF can crack and pop out when sanding. I tend to use one application of CWF on tube seams, then rely on sanded primer to fill any remaining lines.
I wish body tubes would hold CWF as well as launch lugs do. (See the next post!)
One coat of CWF and sanding and lug seams are filled! The CWF locks onto the launch lug seams and won't crack or fall out when sanding.