How much pre-finish prep block sanding?

Hey there, after six weeks of playing with samples I finally feel I've found a method & finish to go with. The question I have now is how much pre-finish block sanding is required on average? How does one know when the job is finished? Thanks!

Just use a block of wood or a flat eraser and sand until the finish is dull with no shiny spots. Any shiny spots would be low spots in the finish. if you have to apply more coats of sealer till it's level. Here's some good info http://www.reranch.com/101.htm

I think he means how much sanding on the raw wood.

I think he means how much sanding on the raw wood.

Correct, Sir!

when there are no visable scratches...Its very hard to see every scratch, look in really good light, at every angle, and with a magnifying glass. And you'll still miss a few lol., Also, sand to 400 or 600.

Doh, in that case http://www.reranch.com/101a.htm. For bare wood you dont need to go finer than 220, 320 at the most. Be sure to sand with the grain. If you go finer your basically polishing the wood and closing the pores which prevent any stain or sealer from penetrating and you could have problems with adhesion. It's the layers of finish that create the smooth surface.

Doh, in that case http://www.reranch.com/101a.htm. For bare wood you dont need to go finer than 220, 320 at the most. Be sure to sand with the grain. If you go finer your basically polishing the wood and closing the pores which prevent any stain or sealer from penetrating and you could have problems with adhesion. It's the layers of finish that create the smooth surface.

oops I meant 320-400. I did to 400. 600 would be overkill I think.

I sand up to 320 until it looks and feels smooth. Then apply one coat of sanding sealer, the grain filler (if necessary) and then apply more sanding sealer and sand etc..

Just as another point of reference, Bob Flexner, in 'Understanding
Wood Finishing', says that it's not necessary to go past 220.
I recommend his book.

Examine your guitar body for deeper scratches in bright sunlight. Ron Kirn's posts taught me this, and he is spot on. No other light works as well. Period.

What kind of wood? Will it need grain filler?

Thanks again for the replies! This is a swamp ash body & I'm going with the Minwax Polycrylic for grain filler.

I sanded the body down with both a 3x5 sanding block & an eraser wrapeed in sandpaper until my threshold of monotony had been reached (& its pretty high).

So far I've put on 4-5 coats of Zinsser Seal Coat & knocked it down a bit after each application (& >6hr dry/cure time) and let it sit for 48 hrs before my first application of Polycrylic, which I'll sand down & recoat again tonight.

I keep asking why I thought this would be less hassle than laquer... Oh yeah, I didnt want to wait 30 days for curing :oops: :oops: & then theres the durability thing......

Is sanding really needed between every coat of shellac?

A shellac coat should "melt" into the previous shellac coat, just
like lacquer -- so I'd guess that not every coat would need to
be sanded.

Anyone have thoughts/experience on this?




Thanks again for the replies! This is a swamp ash body & I'm going with the Minwax Polycrylic for grain filler.

I sanded the body down with both a 3x5 sanding block & an eraser wrapeed in sandpaper until my threshold of monotony had been reached (& its pretty high).

So far I've put on 4-5 coats of Zinsser Seal Coat & knocked it down a bit after each application (& >6hr dry/cure time) and let it sit for 48 hrs before my first application of Polycrylic, which I'll sand down & recoat again tonight.

I keep asking why I thought this would be less hassle than laquer... Oh yeah, I didnt want to wait 30 days for curing :oops: :oops: & then theres the durability thing......

Is sanding really needed between every coat of shellac?

A shellac coat should "melt" into the previous shellac coat, just
like lacquer -- so I'd guess that not every coat would need to
be sanded.

Anyone have thoughts/experience on this?


In my case I wanted the shellac in the grain to bring out the definition moreso than just a sealer. I'm unsure whether or not I would have got the desired results if I hadnt sanded between coats.

I am at my final sanding stage and went to 320, there are a couple of spots i need to redo mostly around the lower and upper horns.

I too will be using Zinssers Seal Coat, hoping to pick some up this week.

EW57 how did you apply the shellac?

Bill

:shock:

EW57 how did you apply the shellac?

Bill

I preferred a foam brush :shock: as the first ones I picked up didn’t say anything about incompatibility with lacquer & shellac, although I later found that this is a no-no as it supposedly will melt the foam. I don’t know if it is the Zinsser formula, that a guitar body is relatively small & can be coated quickly, or if it was that I was only using the brushes once, but I didn’t notice anything that I’d classify as “melting”. But, as always, proceed at your own risk.

You can also wipe Seal Coat on, but I think it goes on quite a bit thinner.

Will you be uploading any pictures?

Bill