Using Abalone

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Dave M
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Using Abalone

Post by Dave M » Fri Jun 15, 2018 5:27 am

Forgive me if this is too basic a question but I am trying to use abalone for a rosette for the first time.

I had to throw my first top out due to a mistake with the (falcate) bracing and didn't that hurt, but I had inlaid a layer of shell with a couple of purfling lines round it for the rosette and when I came to levelling the shell it did not like being scraped at all. There was crumbling and breaking up and that lovely gloss over the figure was lost.

So do we have to get the shell inlay to exactly match the final surface of the top? Or is there a way of thinning it down, maybe with fine abrasives?

And a follow up: how do we deal with the ineveitable small gaps? CA glue? So we have to flood with shellac first so as to not stain the spruce?

Confused of Somerset!


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Allen
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Re: Using Abalone

Post by Allen » Fri Jun 15, 2018 6:31 am

I use my StewMac fret leveling files to knock it down to the surface. Hard sanding block with sandpaper will also take it down.

Yes, thin CA will fill any small gaps.
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kiwigeo
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Re: Using Abalone

Post by kiwigeo » Fri Jun 15, 2018 10:01 am

I used abalone on two of my early builds. I inlaid the pieces so they were 1-2mm proud of the top and then just sanded back. Abalone isn't that hard...it's basically calcium carbonate. On the Mohs Hardness Scale it's about 3-4 which isn't that hard. It'll work easily with moderate grit sandpaper.
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Steve.Toscano
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Re: Using Abalone

Post by Steve.Toscano » Sun Jun 17, 2018 12:39 pm

Dave M wrote:
Fri Jun 15, 2018 5:27 am

So do we have to get the shell inlay to exactly match the final surface of the top? Or is there a way of thinning it down, maybe with fine abrasives?
I dont use it much myself, but a lot of my students do.
I get them to cut the channel so the shell is just proud of the top. Talking less then a quarter a mm.
Then sand it down by hand useing a hard block. Not much too it, takes a student about 10mins to sand it flat and remove any excess glue.
Dave M wrote:
Fri Jun 15, 2018 5:27 am
And a follow up: how do we deal with the ineveitable small gaps? CA glue? So we have to flood with shellac first so as to not stain the spruce?
I get them to use fish glue to glue in the shell pieces. So any gaps will be filled by the glue when installed. I prefer fish glue over CA, as it has a longer opening time for setting up intricate pieces, is tacky, dries somewhat clear, and doesn't stain spruce. Yet still adheres well to shell.

CA would also work as a post install gap filler, but yes, will need to seal the spruce with shellac first.

When sanding shell make sure to wear the usual respiratory protection, the dust is a nightmare.
Last edited by Steve.Toscano on Sun Jun 17, 2018 1:06 pm, edited 1 time in total.

simso
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Re: Using Abalone

Post by simso » Sun Jun 17, 2018 12:56 pm

It also helps to know if you are using solid Paua shell or laminate, the laminate is built up from .15mm thickness cuts and then glued together, so this may be the cause of your crumbling, solid shell sands really easy.

Also laminates are not the same between manufacturers, I have one sheet of MOP from one manufacturer which sands beautifully but at 1.5mm thickness it costs me 400 dollars for sheet, another manufacturer from Korea sold me some of theirs and it’s also 1.5mm thick laminate at a cost of 80 dollars a sheet, but it’s pretty average (using kind words here)

The alternative is to use super thin shell and sit it below the surface and pore fill over the top, this allows you to get a high glosss finish to the shell area

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Re: Using Abalone

Post by simso » Sun Jun 17, 2018 1:02 pm

This is .15mm shell with clear fill over the top, no sanding

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56nortondomy
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Re: Using Abalone

Post by 56nortondomy » Sun Jun 17, 2018 6:03 pm

That's a great tip Steve, I'm about to inlay a shell piece I've had engraved and I've been worried about sanding it in case I lose the engraving. What do you use to pour fill over it? This is a new guitar so will be going into raw timber. Wayne

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Re: Using Abalone

Post by simso » Sun Jun 17, 2018 6:14 pm

Whatever finish the Guitar is, I simply drip fill the finish in and then scrape it to height, possibly better ways of doing it, but I try not to make it to complicated for myself.

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56nortondomy
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Re: Using Abalone

Post by 56nortondomy » Sun Jun 17, 2018 7:05 pm

Thanks Steve, i'll be using lacquer on it, might try it out on a little bit of scrap first, thanks for the reply. Wayne

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Re: Using Abalone

Post by Dave M » Sat Jun 30, 2018 3:48 am

I have been unable to log in for a while so thanks to everyone for the advice. In the meantime my second go has been much better. After sanding the shell is a little dull, but I imagine the finish will bring that back up.
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Steve.Toscano
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Re: Using Abalone

Post by Steve.Toscano » Sat Jun 30, 2018 9:39 am

It should, yes, ensure you sand the shell to a high grit. Typically 800 is enough.
You can do this in your finish prep stage.

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Trevor Gore
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Re: Using Abalone

Post by Trevor Gore » Sat Jun 30, 2018 12:54 pm

Dave M wrote:
Fri Jun 15, 2018 5:27 am
So do we have to get the shell inlay to exactly match the final surface of the top? Or is there a way of thinning it down, maybe with fine abrasives?

And a follow up: how do we deal with the ineveitable small gaps? CA glue? So we have to flood with shellac first so as to not stain the spruce?

Confused of Somerset!
Dave, if you're having trouble with scraping, the alternatives are filing, hard block sanding, or a thickness sander, if you have one. Gerard would just put the top with inlaid rosette straight through his wide belt sander. That leveled it!

However, it is best to inlay as close to flush as you can, the reason being that if you have matched colours/patterns between solid shell segments, that matching disappears if you take off more than ~ 0.1mm.

Regarding gaps, they are not inevitable. Individually fit the ends of segments and keep the amount of glue under control so you can be sure you can see that the butt joint is tight. One advantage of assembling rosettes off the guitar (as shown in the book) is that if you don't like the result it's pretty easy to redo. Re-doing an inlay direct into a top can be done, but there is much more risk of things going wrong.

If you glue up initially with Titebond, any tiny gaps (typically between the shell and purfling) can be filled with CA glue. The Titebond should have sealed all the end grain, so you don't get any green stains.

Any residual sanding scratches from grits 400 and higher become invisible under a finish.

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Re: Using Abalone

Post by Dave M » Sun Jul 01, 2018 2:53 am

Again thanks. I didn't get the depth of groove as close as I meant to but hard block sanding as Trevor suggested did the trick. I will take it to a finer grit as suggested.

It is NZ Paua. Real fancy looking stuff isn't it? It wouldn't do to use too much of it unless you are going for a real bling model.
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peter.coombe
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Re: Using Abalone

Post by peter.coombe » Sun Jul 01, 2018 9:59 am

I use solid Paua Abalone and glue the strips in with CA glue. Some woods will stain with CA, so try on scrap first. Myrtle, Qld Maple, NSW Rosewood, Huon Pine which is what I have used so far are all ok. One wood stained badly, can't remember what it was, but I think it was Sassafras so bad idea to use CA on Sassafras. The CA fills all the little gaps nicely. The top is left thicker than final thickness. Once the CA is dry, put it through the drum sander and bring the top down to final thickness. So similar to what Gerard did. As Trevor said, that levels it. Also as Trevor said, try to get the shell as level as possible and take off the minimal amount necessary or else matched joins will start to show. If the top is still too thick, flip it over and sand the back. Final sanding is down to 400, and any scratches disappear under finish.
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56nortondomy
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Re: Using Abalone

Post by 56nortondomy » Sun Jul 08, 2018 6:19 pm

I inlaid the piece of engraved mop, I kept it just below the surface and filled over it and it worked out great, thanks for that tip Steve, I still have another one to do.
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Re: Using Abalone

Post by simso » Sun Jul 08, 2018 8:03 pm

Your welcome, also what a collective of information being given, I too have learnt some stuff following this thread.

I like to use steel wool to return the luster of shell, that being said final sanding with an appropriate grade is just as important as well.

One of the bigger issues I see with my shell work is I use laminated shell 1.5mm thick, each shell layer is .15mm so when you sand to shape you get some ripple looks to the shell which is from sanding through the layers.

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