Sealing and finishing Sitka Spruce top

Drjay · Post by **Drjay** » Thu Jan 08, 2009 11:57 pm

Hi
I am a newbie and am in the middle of building my first flat top. I must admit it is a massive learning curve for me, but getting more adictive each day.
I was wondering if anyone can advise me on how to prepare, seal and finish my sitka spruce top?
With limited research I am led to understand that you have to treat this wood differently from the rosewood back and sides. Is this true?

Kim · Post by **Kim** » Fri Jan 09, 2009 12:47 am

Hi Doc,

Welcome to the ANZLF.

I moved your post into the main build forum so it will get more attention. I will add that your spruce top has no pores to fill so it is easier to deal with than most woods one would generally use for back and sides.

Depending on your chosen finish you can just seal it with shellac or lacquer and it's ready for top coats. But then again you had best wait for others to respond because they may have more refined input than I.

I'm just the welcoming party

Cheers

Kim

Allen · Post by **Allen** » Fri Jan 09, 2009 7:06 am

Welcome to the forum.

I don't do anything with spruce tops prior to finish except to make very sure that they are sanded very smooth. It's easy to leave a coarse sanding mark in the softer wood, and think "She'll be right".

I did try an egg white wash on one Engelman spruce top, but I didn't notice any difference at all, so don't bother with the extra step. Some people use a wash coat of shellac, but I've found that it isn't necessary for applying lacquer as a top coat. It may make a difference with other finishes.

Bob Connor · Post by **Bob Connor** » Fri Jan 09, 2009 7:24 am

Hi and welcome to the forum.

I'm with Allen.

I just sand'em and spray 'em.

What finish are you going to use?

Craig · Post by **Craig** » Fri Jan 09, 2009 8:54 am

DrJay,

I've found I get grain ridges on the soundboard finish when hand applying ( french polishing shellac ) on the soundboard . I think it's the shellac melting into the winter grain lines more so than the summer lines. For this reason , I'm going to experiment with sealing the Spruce with egg white before applying french polished shellac , to see if this will curb the problem.

These grain line ridges don't seem to be such a problem when the shellac is sprayed . Unfortunatley ,the sprayed finish seems to end up a much thicker finish than french polish , and probably not as hard also. It's for this reason I prefer the french polish method .

If you are to spray shellac , be very careful about your choice. I got my fingers severely burnt when spraying U-Beaut's Hard shellac , as did loads of others . The stuff crazy cracked all over ! I'm still fuming about it.! If a company is to put out a product , surely they should at least test it first.
U-Beaut have now changed the formula , which they reckon may resolve the problem. They have lost all credibility as far as I'm concerned and I wouldn't go near any one of their products ever again ! I advise all others to do the same.

Bob Connor · Post by **Bob Connor** » Fri Jan 09, 2009 9:10 am

I get grain lines appearing when I use Pre-cat laquer Craig and I'd probably be disappointed if I didn't because it'd mean that I applied the laquer too thickly.

They usually start appearing about a month after the laquer is applied.

I had the same when using the Hard shelllac as well.

Craig · Post by **Craig** » Fri Jan 09, 2009 9:46 am

bob wrote:I get grain lines appearing when I use Pre-cat laquer Craig and I'd probably be disappointed if I didn't because it'd mean that I applied the laquer too thickly.

They usually start appearing about a month after the laquer is applied.

I had the same when using the Hard shelllac as well.

Interesting that your Pre-cat does that too Bob. I don't really like the look, and would prefer a level finished surface to match the back and sides . I'm keen to see if the egg white sealer on Spruce will curb the problem . I'll report the outcome when I get to that stage

Allen · Post by **Allen** » Fri Jan 09, 2009 5:54 pm

I get the ridges too, Usually about 1 - 2 months after buff out. I think it is either buffing back too soon, or more likely movements in the wood due to RH fluctuations.

Either way, I like the look of them if they aren't too pronounced. The flatter, thinner and glossier the finish, the more you're going to notice them.

Bob Connor · Post by **Bob Connor** » Fri Jan 09, 2009 5:59 pm

I've got a 30 year old D-18 that's been finished with nitro. It's got 'em as well.

I also have a Takamine that I use for stage work. It hasn't got them but it's probably a polyester finish and it's easy to see that the finish is very thick.

Hesh1956 · Post by **Hesh1956** » Sat Jan 10, 2009 10:26 am

It's RH fluctuations causing wood movement and seen more often on guitars with thin finishes. It's a good thing - part of the charm IMHO.

Kim · Post by **Kim** » Sat Jan 10, 2009 11:41 am

My old Maton with a nitro finish had them as well, but now most of them have been refilled with crusted salt from my arm pit.....it's true

Cheers

Kim

DarwinStrings · Post by **DarwinStrings** » Sat Jan 10, 2009 12:18 pm

Note to myself....If I ever get the opportunity to play Kim's old Maton....... DON'T.

Jim

Allen · Post by **Allen** » Sat Jan 10, 2009 12:42 pm

He just takes it to a whole new level, doesn't he.

Drjay · Post by **Drjay** » Wed Jan 14, 2009 11:16 pm

Thanks all for your interesting responses to my initial enquiry. I have read about the egg white technique in this forum, but sweat salt Mmmm?
As I mentioned earlier this is my first build and it is proving to be a process of wins and losses (and a lot of sweat). However, you do learn a lot from just getting on and doing.
Thanks
Jim

Alfred J · Post by **Alfred J** » Thu Jan 15, 2009 1:31 am

With Lutz spruce (can't comment on Sitka - never used it.) I don't get those shellac grain ridges. Maybe I've been lucky so far. Surface prep might have something to do with it. I progress through to 1500 grit. On the first guitar I used the True Oil sealer but switched to shellac after the bottle ran out. I've also used Shellac twice under KM9, the water based finish that Lmmi sells.

Has anyone had that grain ridge problem using shellac over Adirondac with very pronounced grain lines? i have an Adirondac top (one only) that I would hate to ruin.

Advice would be greatly appreciated.

Bob Connor · Post by **Bob Connor** » Thu Jan 15, 2009 8:01 am

Hmm. I'd be loathe to call it a problem.

In fact I'd be suspect of any guitar that didn't exhibit the grain lines.

I believe I've heard Rick Turner (an experienced luthier) state the same.

DarwinStrings · Post by **DarwinStrings** » Thu Jan 15, 2009 10:20 am

I have a 40 year old fender and it has only a thin veneer of spruce on its ply deck, it still has the lines.

Jim

Allen · Post by **Allen** » Thu Jan 15, 2009 7:37 pm

bob wrote:Hmm. I'd be loathe to call it a problem.

In fact I'd be suspect of any guitar that didn't exhibit the grain lines.

I believe I've heard Rick Turner (an experienced luthier) state the same.

Yep, I like em.

A good way to think about this, is that wood is somewhat of an elastic product. Changes in dimensions in all axis with fluctuations in environmental conditions. If your finish is thin and flexible, it's going to conform to these changes, and you are going to something other than a mirror smooth surface that you started with. If your finish is something other than thin and flexible, you will not see the grain ridges.

matthew · Post by **matthew** » Thu Jan 15, 2009 10:04 pm

I'm with Hesh here.

I'm not sure i understand the dread of a slightly textured surface. For me, a perfectly glossy flat finish screams PLASTIC at me, whereas when I can see and even feel the grain, even slightly, it purrs "woooooood".

I have a lacquered Aria acoustic that I rarely pick up now. It just feels plastic to me. My old maton, however (before it got nicked 25 years ago) felt like wood straight out of the factory.

I knew who took it but I could never prove it. Ooooh I get really angry whenever I think of that horrible event in my life ...

kiwigeo · Post by **kiwigeo** » Fri Jan 16, 2009 12:36 am

Kim wrote:My old Maton with a nitro finish had them as well, but now most of them have been refilled with crusted salt from my arm pit.....it's true

Cheers

Kim

Topless man playing a Maton...oooooooooh!!

Rick Turner · Post by **Rick Turner** » Fri Jan 23, 2009 2:57 am

Spanish luthier Jose Romanillos is a proponent of the egg white sealing technique. I learned about it from Monica Esparza, a wonderful classical builder here in the 'States.

And yes, I like to see the grain lines of the top evident. To me it's an indicator of a thin finish, whether it's French polish, lacquer, shellac, varnish, or one of the poly finishes.

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Sealing and finishing Sitka Spruce top

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