Pumice alternative

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Pumice alternative

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mounirben

Posts: 43
Joined: Sep. 12 2013

Pumice alternative

Hello guys,

I was wondering if there is alternatives for pumice powder, like baby powder for examplr or else (shipping time very long for where iam)

REPORT THIS POST AS INAPPROPRIATE | Date May 7 2015 22:33:29

estebanana

Posts: 9351
Joined: Oct. 16 2009

RE: Pumice alternative (in reply to mounirben)

The cuttlefish bones that pet stores sell to put in Parrot cages for the birds to peck at. Yi can crush them and use the powder to fill pores.

Pumice is really hard to beat. You can also use Super Glue...but it's nasty.

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REPORT THIS POST AS INAPPROPRIATE | Date May 8 2015 1:18:59

Flamingrae

Posts: 220
Joined: May 19 2009

RE: Pumice alternative (in reply to mounirben)

Rottenstone should work - it's a bit finer than pumice. Not tried tripoli powder but that should do too. Didnt know about cuttlefish Este - might try that for something else. My pennyworth.

REPORT THIS POST AS INAPPROPRIATE | Date May 10 2015 12:27:50

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Pumice alternative (in reply to mounirben)

Sawdust will work but it takes several applications, sand it off the end grain of the same wood you're trying to fill, this gives you the finest dust with a good color match. The best pore filler is epoxy surfacing resin second best is super glue. If you use super glue (cyanoacrylate) get the odorless medium viscosity, it won't burn your eyes and nose.

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REPORT THIS POST AS INAPPROPRIATE | Date May 10 2015 14:10:19

keith

Posts: 1108
Joined: Sep. 29 2009
From: Back in Boston

RE: Pumice alternative (in reply to mounirben)

not sure if folks have used it but I was wondering if baking soda would work. baking soda has some grit to it.

REPORT THIS POST AS INAPPROPRIATE | Date May 10 2015 14:43:35

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Pumice alternative (in reply to mounirben)

One caveat about using epoxy surfacing resin, you can't put it over any finish even a thin coat of shellac, it has to be used on bare wood or it won't adhere properly.

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REPORT THIS POST AS INAPPROPRIATE | Date May 10 2015 18:10:35

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Pumice alternative (in reply to mounirben)

Dont you have any problems with lacquers/varnish adhering to epoxy.
I´ve built a couple of boats and epoxy can create nasty issues for whatever you put on top. It bubbles off if the epoxy doesnt gass of which can take a long time and in a few examples never happen.
Besides, be aware that some people devellop serious allergic reactions to epoxy. And the problem with allergic reactions is that they may spread from one thing to others once the body starts loosing its auto defense .

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REPORT THIS POST AS INAPPROPRIATE | Date May 10 2015 20:59:38

estebanana

Posts: 9351
Joined: Oct. 16 2009

RE: Pumice alternative (in reply to mounirben)

The thing about fillers is there are two basic ways to go:

One type of fillers where the substance can be rendered semi transparent when it is wetted by which ever 'glue' you use to stick it in the pores.

The other is filler than stays opaque and does not reflect light through it.

Pumice, chalk, calcium carbonate, etc will become partially transparent if used well and it allows the refractive index of the wood to remain high. It means the light entering the wood will penetrate through the pore filler and reflect back out from a deeper layer in the wood. Keeping the refractive index high in this way creates deeper looking finishes.

Using the opaque fillers, wood dust, acrylic, microballoons with resin based mediums make an opaque barrier with lowers the refractive index. It makes it more difficult to get deep looking finishes.

Rottenstone is also fairly opaque, but the gypsum, calcium carbonate, cuttle bone, pumice, white marble dust, can all be semi transparent when they are saturated with shellac.

But it depends on how you like the finish to look, sometimes wood dust is good looking, sometimes pumice, to an extent it also depends on the kind of wood you are working with and the wood color.

It all works, but just be aware that different pore filling materials effect the look of the finish in a subtle way. The other day I used ebony dust to pore fill a section of head stock that I wanted to be dark...then I used pumice on the body. You can use different pore filling materials on different parts of the guitar to great effect.

Refractive index is a big subject but here's kind of how it works in pore filling.

Images are resized automatically to a maximum width of 800px

Attachment (1)

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REPORT THIS POST AS INAPPROPRIATE | Date May 11 2015 0:25:05

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Pumice alternative (in reply to Anders Eliasson)

quote:

ORIGINAL: Anders Eliasson

Dont you have any problems with lacquers/varnish adhering to epoxy.
I´ve built a couple of boats and epoxy can create nasty issues for whatever you put on top. It bubbles off if the epoxy doesnt gass of which can take a long time and in a few examples never happen.

Anders,
After several bad experiences using epoxy (joint failures, reactions with some woods, etc.) I avoided using epoxy for years; but the new generation of epoxy resins like z-poxy, Smith's system III, etc. have made me a convert. I use mostly z-poxy surfacing resin since it is very forgiving about measuring the two parts and thins beautifully with denatured alcohol and has no odor. It makes the grain really stand out on rosewoods. We normally put on two coats sanded back to bare wood then finish with a very thin coat which is lightly sanded before applying shellac then finishing with a few coats of very thin lacquer. Like everything there's a learning curve with using it so make sure to practice on scrap wood at first. We use it on every guitar even blancas.

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REPORT THIS POST AS INAPPROPRIATE | Date May 11 2015 14:19:10

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Pumice alternative (in reply to mounirben)

Ok, you use Shellack as a sealer. that makes sense.

I know modern epoxys and thats what i used when building glued lapstrake/clinker boats.

I never had any issues myself, but i know others who had serious problems with getting anything to adhere on top of the epoxy.

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REPORT THIS POST AS INAPPROPRIATE | Date May 11 2015 19:07:04

estebanana

Posts: 9351
Joined: Oct. 16 2009

RE: Pumice alternative (in reply to mounirben)

West System Epoxies & resins has a whole system worked out with micro-ballon filler and various resins that are meant for painted coatings to stick to them.

The boat industry has come a long way with resins.

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REPORT THIS POST AS INAPPROPRIATE | Date May 11 2015 23:49:45

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Pumice alternative (in reply to estebanana)

Stephan,
West system III is the one I meant, I got it confused with Smith's clear penetrating epoxy sealer which is a similar product that I didn't like as a pore filler. West system III is and excellent filler and very clear but requires very accurate measurement when mixing the two parts.

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REPORT THIS POST AS INAPPROPRIATE | Date May 12 2015 14:47:51