Grain filling Swamp Ash

vanlooy1

I've just grain filled a Swamp Ash body as per @SteveRobinson's guide and sanded back with 320 grit, does anyone know of an effective method of checking missed/unfilled areas? It all looks okay to my novice eye but don't want to move on until I'm certain that the whole body is filled.

It's one of @GSPBASSES superb rb6T bodies (build thread to follow)!

MattNovak

I find a quick spray of primer helps show the spots I’ve missed, but I’m sure others with more experience will contribute. And yes - build thread!

vanlooy1

Thanks, I’m planning a black top and natural sides and back (nitro) so was going to just spray straight on to sealer

Winny_Pooh

Sealer is primer. Shoot some sealer and then lightly sand back. You can grain fill on top of that before you put on more sealer coats. 

vanlooy1

Winny_Pooh said:

Sealer is primer. Shoot some sealer and then lightly sand back. You can grain fill on top of that before you put on more sealer coats. 

Thanks, I’ll give that a crack, I guess I’m looking for pin holes then?

Winny_Pooh

When you flatten your sealer you will see shiny divots, that means you need to flatten more to avoid those divots as they only stay around later when you accidentally sand through topcoat to remove them.

SimonBarden

Or add more grain filler, sand back and then check again with another mist coat and sand-back.  The shiny divots/dips are where the wood is lower than the rest of the surface and your sealer/primer has filled them and is relatively shiny because it hasn't been sanded.  In simply sanding back until the wood surface is level with the base of the divots, you could well be exposing more unfilled pores.  It's not like the situation where you've got many layers of finish on and you've got the depth of finish to allow sanding the top layer down by up to 1mm or so until it's all perfectly flat with plenty of finish left on the guitar. You're right on bare wood, and some of those pores in the wood that you cant see (and the filler can't reach yet) are only just below the surface.  Sanding even 0.5mm off can then expose them, causing issues if you then simply go and apply your finish on top without further filling.  

Almost all grain fillers will shrink to a small extent as they dry, so I find it best to take your time and certainly do two, maybe three applications.   I've been trying Solarez UV curing grain filler recently and that doesn't noticeably shrink at all (there's no solvent to evaporate and reduce its mass), but I'm not totally convinced about the way nitro sits on top of it at the moment, so I've got to do some more testing before I'd fully recommend it.

vanlooy1

Thanks all, I’ve given it another going over with the filler, I’ll be sanding back tonight and then give it a squirt with the sealer and see where I’m at. All advice is very welcome as this my first nitro job and it’s a bit daunting to be honest! I’d rather balls it up as unspectacularly as possible!!