A question about sealers

ARandall

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Just wanting to have a little bit of a discussion on sealer and how it is used under nitro.

I use Behlen sealer usually, either the Qualalac or Vinyl stuff. Occasionally I've also wiped on some shellac.

A lot of them mention quick build......which seems to indicate that they are filling pores to a degree in a quicker way than normal coats of nitro. Is this one of their functions.......like putting on some coats and doing a minor sandback so you use way less nitro clear??
 

B. Howard

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No.... quick build refers to resisting soaking into the wood fibers and sealing the wood quickly. If you use the old school method of cutting clear with thinner 50% you will need about 4 coats to seal the wood so finish stops soaking in and you do not get dry spots in your first coats which messes with film thickness and will haunt you when you level to buff. At no point should you consider a sealer as a pore filler unless it is made specifically as a dual purpose like a polyester or some highly specialized amino-alkyds. Sealer is softer than actual finish so extra sealer build under a coat of nitro that is too thin will likely check and peel badly.

One sealer you mention is a nitro type and the other is a vinyl and there are differences here..... mainly flexibility.
 

LtDave32

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Just wanting to have a little bit of a discussion on sealer and how it is used under nitro.

I use Behlen sealer usually, either the Qualalac or Vinyl stuff. Occasionally I've also wiped on some shellac.

A lot of them mention quick build......which seems to indicate that they are filling pores to a degree in a quicker way than normal coats of nitro. Is this one of their functions.......like putting on some coats and doing a minor sandback so you use way less nitro clear??
I use Campbell lacquer-based sanding sealer. It's designed to sand back for a quick leveling process, and so far it has been exactly that. You can sand it in 20 minutes, it sands easy, and it absolutely cuts down on nitro lacquer coats required for leveling.

I spray a full coat (three times around the instrument), let that dry for a few hours, spray another full coat, let that dry for a day, then the next time I sand it back, the grain pits are gone, the instrument is fully sealed, and I'm on my way to color coats.

If I merely shellac-sealed (like I used to do), then start build coats of lacquer, I'd be dealing with shrink-back for several days. Even with grain filling, swamp ash is a tough wood to get level and grain filled sufficiently.

Mahogany is easier to grain fill.
 

ARandall

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Thanks guys.

Is it common for sealer which you have sprayed and got to a semi-level state through sanding to seemingly shrink into pores a lot once the first coats of nitro go on?? It seems like that has happened a couple of times with me in the past......where you think you are ready for say an opaque or metallic only to have it either become very grain showing or telegraphing lumps you'd thought were no longer issues.

I ask as the last goldtop did that......and I have 3 metallic guitars to spray soon.
 

Skyjerk

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Thanks guys.

Is it common for sealer which you have sprayed and got to a semi-level state through sanding to seemingly shrink into pores a lot once the first coats of nitro go on?? It seems like that has happened a couple of times with me in the past......where you think you are ready for say an opaque or metallic only to have it either become very grain showing or telegraphing lumps you'd thought were no longer issues.

I ask as the last goldtop did that......and I have 3 metallic guitars to spray soon.
It depends on the type of sealer Id guess.

I use simtec ( polyester ) easy sanding sealer. Once that stuff cures (overnight) it NEVER shrinks. I shoot 3 coats, let cure overnight, sand flat and thats it. Assuming its perfectly flat after sanding, you'll never see a pore. ever.

Good for transparent or opaque finishes

Its a godsend for swamp ash, but I use if for mahogany as well :)
 

LtDave32

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Thanks guys.

Is it common for sealer which you have sprayed and got to a semi-level state through sanding to seemingly shrink into pores a lot once the first coats of nitro go on?? It seems like that has happened a couple of times with me in the past......where you think you are ready for say an opaque or metallic only to have it either become very grain showing or telegraphing lumps you'd thought were no longer issues.

I ask as the last goldtop did that......and I have 3 metallic guitars to spray soon.
I've had zero shrink back. None whatsoever. Once I've level-sanded and shot another coat, then level sanded again, If I've still got grain valleys, I'll shoot another coat.

Never had to shoot more than 2 1/2 times, nor level sand more than twice. And that's what it's for; it's a level-sanding sealer, so it sands super easy and doesn't clog up.

(Well, it does clog a tiny bit if you go at it 20 minutes after spraying, but if you wait several hours, it doesn't clog the paper at all..)

On the other hand, back in my early days I'd use just nitro as build coats. Pretty soon I got to the point to where the grain was all full, I'd level sanded, and shot a coat over that.

Two weeks later, lo and behold, I've got tiny evidence of some shrink-back into the pores.

With Campbell C10189 lacquer based sanding sealer, I have no shrink issues.
 

bcguitars74

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Great thread! I've just acquired my first spray gun and am getting organised to use it ..

In the UK here I've been looking at sealers and a popular one is cellulose based. How does this compare to other sealers? My only experience to up to now is with brushing on shellac ..
 

LtDave32

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Great thread! I've just acquired my first spray gun and am getting organised to use it ..

In the UK here I've been looking at sealers and a popular one is cellulose based. How does this compare to other sealers? My only experience to up to now is with brushing on shellac ..
The deal with shellac, which was used as a sealer for guitars (and other wood work) in the 50's and 60's was that "shellac sticks to anything, and anything sticks to shellac".

Which is pretty much true. It does provide a barrier between the wood pores and the finish, and lacquer sticks over it quite well.

It is what I used for a sealer over bare wood for years.

But it has virtually no surface or grain-filling qualities whatsoever.

Many of these sanding sealers not only provide a surface that lacquer adheres to well, but also provides a medium that can be sanded to get rid of surface imperfections.

Some may not agree totally with this, but it has been my experience every time.

And a gallon goes a long, long way. I'm not even on my second gallon after 6 guitars. I still have more.

So I consider it a value, for nitrocellulose lacquer coats and sanding back, more coats, etc would have taken its place at a much greater expense.

Not to mention saving a ton of time.
 

B. Howard

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I use Campbell lacquer-based sanding sealer. It's designed to sand back for a quick leveling process, and so far it has been exactly that. You can sand it in 20 minutes, it sands easy, and it absolutely cuts down on nitro lacquer coats required for leveling.
Assuming it is the C117029 as it is the only one I know they make with a filling ability. I used that on a few guitars.... Try it on an oily wood like rosewood instead of mahogany and it will likely be the last time you use it. At least without isolante under it as it is seriously effected by PH which is affected by the oils in the wood. Also not a Lacquer but a acid catalyzed amino alkyd.....
 

LtDave32

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Assuming it is the C117029 as it is the only one I know they make with a filling ability. I used that on a few guitars.... Try it on an oily wood like rosewood instead of mahogany and it will likely be the last time you use it. At least without isolante under it as it is seriously effected by PH which is affected by the oils in the wood. Also not a Lacquer but a acid catalyzed amino alkyd.....

It's Campbell C10189, Lacquer-based Sanding Sealer.

This the result of one strong coat, a level-sanding (about 10 minutes worth), then another coat, then another sanding, but very brief, then a light coat over that:
20181030_115655 (1).jpg


Completely filled the grain.

The next day, I shot a color-coat over that, then began the clear-coating.

Absolutely no evidence of shrink back during the entire build, from the color coat to a month later when the client received the guitar.

I cannot speak for others or the products they use, I can only speak of the product I use, and how it works for me. The above is an example.
 

ARandall

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On a sidenote.....I hadn't realised how much wood removal a b-bender requires!!


Thanks for the discussion guys, its been all great info on the various products and techniques used.
 

LtDave32

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On a sidenote.....I hadn't realised how much wood removal a b-bender requires!!


Thanks for the discussion guys, its been all great info on the various products and techniques used.
yeah, but it's really not that heavy. The bender mechanism still slightly outweighs the removed wood.

So I hand-select really light body spreads. They can vary (for a 16 X 20 two-piece spread) from 6.9 lbs to just under ten lbs. The weight is written on the end grain, and I dig through the pallet to find the light ones.

Commonly, after I've removed the wood for the bender unit, routed the body, pup routs, etc we've got a bare body weight of 2.9 to 3.1 lbs, if I select a 7.5 to 8 lb spread.

Which usually results in a finished guitar with B bender installed to be about 7 lbs total. Right in the ball park. Last one I made for MLP member mudface weighed 6.9 lbs shipped.

You're welcome for the advice, Randall..
 

B. Howard

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It's Campbell C10189, Lacquer-based Sanding Sealer.....

.....Completely filled the grain......

I cannot speak for others or the products they use, I can only speak of the product I use, and how it works for me. The above is an example.
This product is not designed as a filler...... The fact that it is working initially without shrink back at 30 days out is rather incredible actually but i could see it on a small pore wood. I would still be wary of problems down the road with checking and peeling from having to much soft substrate under to little hard finish.
 




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