Opaque finish on Alder

Sean6247

Active member
Messages
33
Hi All,

I have an Alder Strat body coming soon and I plan on finishing the guitar in opaque white acrylic lacquer.

My plan at this point is to fill with a water based grain filler, seal with Bullseye Shellac, primer, color, then clear.

I have read Alder doesn’t need filler. My test pieces show very small grain depressions. I didn’t fill or seal the test subjects, because I was focusing on the ghost pearl I am applying over the white.

I guess my main question is, will shellac adequately fill the grain? Or, should I fill and then shellac?
 

Rick

Senior member
Messages
4,510
I never bothered to grain fill alder.  Everyone is different but I bet when you get your body you'll see grain filling as redundant.
 

DuckBaloo

Senior member
Messages
299
Why shellac and primer? For opaque finished the primer usually replaces the sealer coat.

A good primer should handle the sealing and the filling on a non-porous wood like alder.
 

Sean6247

Active member
Messages
33
DuckBaloo said:
Why shellac and primer? For opaque finished the primer usually replaces the sealer coat.

A good primer should handle the sealing and the filling on a non-porous wood like alder.

I hadn’t considered primer acting as the sealer. The primer I used still left some grain depressions which I don’t want on my guitar. I am wondering if shellac will act as a filler since the grain is so small.
 

DuckBaloo

Senior member
Messages
299
You have to sand the primer back to level. If you can’t sand it flat and level without sanding through, then you haven’t sprayed enough primer.

When you spray the primer, no matter how many coats, it is going to follow the contour of the wood, but it is building up. Not unlike the top half of this Popular Woodworking illustration (this is actually an illustration promoting grain filling, disregard the bottom half) ..
woodpores2wcolor.jpg


You level it by sanding the higher “field” down level to the “lower” grain. Lay it on thick, sand it back thin.

It is the most labor intensive part of the process and you will probably find yourself cussing loudly sometime during it and having to reach for the spray gun/can. But this is when the hard work is necessary to get that mirror-smooth finish at the end. 

The primer, which is high solid for faster coating is better the shellac (though they do make shellac based primers like B-I-N). Either way you aren’t getting around the elbow grease.

With open-pored woods like ash and mahogany, the pores are so large and deep than it would take forever to build up enough primer or sealer to fill the grain, that’s why we grain fill as well (but we have to do both for mirror-smooth finishes).

Despite all I said above, there is no harm in grain filling alder, and some pieces really need it. 
 

Sean6247

Active member
Messages
33
DuckBaloo said:
You have to sand the primer back to level. If you can’t sand it flat and level without sanding through, then you haven’t sprayed enough primer.

When you spray the primer, no matter how many coats, it is going to follow the contour of the wood, but it is building up. Not unlike the top half of this Popular Woodworking illustration (this is actually an illustration promoting grain filling, disregard the bottom half) ..
woodpores2wcolor.jpg


You level it by sanding the higher “field” down level to the “lower” grain. Lay it on thick, sand it back thin.

It is the most labor intensive part of the process and you will probably find yourself cussing loudly sometime during it and having to reach for the spray gun/can. But this is when the hard work is necessary to get that mirror-smooth finish at the end. 

The primer, which is high solid for faster coating is better the shellac (though they do make shellac based primers like B-I-N). Either way you aren’t getting around the elbow grease.

With open-pored woods like ash and mahogany, the pores are so large and deep than it would take forever to build up enough primer or sealer to fill the grain, that’s why we grain fill as well (but we have to do both for mirror-smooth finishes).

Despite all I said above, there is no harm in grain filling alder, and some pieces really need it.

Thanks for this post. I had not considered using primer in this fashion. Most finishing schedules I have read just instruct spraying a couple coats of primer, quick sanding, then color. They also include the same instructions for filling, sealing, color.... etc. I never honestly understood the purpose of primer for most applications and have just used it “because I’m supposed to”.
 

Sean6247

Active member
Messages
33
DuckBaloo said:
BTW, it’s great that you got scrap to practice on.  :eek:ccasion14:

I bought some alder from a local hardwood supplier to create color swatches for the ghost pearl and to check out a couple different colors. I was not as meticulous as I normally would have been when finishing a body, because I was focused on the color. Fortunately, that educated me on what can happen when foundational steps are not given their proper weight.
 

DuckBaloo

Senior member
Messages
299
Sean6247 said:
Thanks for this post. I had not considered using primer in this fashion. Most finishing schedules I have read just instruct spraying a couple coats of primer, quick sanding, then color. They also include the same instructions for filling, sealing, color.... etc. I never honestly understood the purpose of primer for most applications and have just used it “because I’m supposed to”.

Primer serves a few jobs.

  • Lacquer is lousy at sticking to bare wood, but it sticks well to primer and primer sticks well to clean bare wood
  • Primer is high solids, and is fast to spray on as a sand-able "leveler" coat to get a smooth finish
  • Primer gives a good opaque base so you don't have to spray as many color coats.

Shellac is great as a wash coat to seal wood before wood-based fillers. Shellac is also the "rosetta stone" of finishes, it'll still to anything...acrylic, nitro, polyurethane, polyester, tru oil, oil based filler, water-based filler, bare wood, silicon contaminated wood, tape residue, etc. and everything will stick to it. If you have an issue with two incompatible finishing products, or fish eye from contamination, a coat of shellac will usually fix it. It has it's downside though, it's fine against water, naphtha and mineral spirits, but simple alcohol with dissolve it. And it hates heat, so you have to be careful if using it on something you'll put to a polishing wheel.
 
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