# Epoxy Accelerator



## NCMau (Jan 30, 2019)

I just got some epoxy A&B glue but I would like to speed up the process. I am working with 8oz bottles. Any suggestions on the type of accelerator? Can CA glue accelerator be used with epoxy?


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## RichT (Oct 14, 2016)

Did you buy 5 minute epoxy? That'll be plenty fast. If you got a slower curing one, the only thing that'll affect it is heat. Best thing to do is go get some 5-minute epoxy.


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## pottz (Sep 15, 2015)

> Did you buy 5 minute epoxy? That ll be plenty fast. If you got a slower curing one, the only thing that ll affect it is heat. Best thing to do is go get some 5-minute epoxy.
> 
> - Rich


yeah 5 minutes isn't fast enough,i find it's too fast even when im in a hurry.


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## SMP (Aug 29, 2018)

You talking 2 part epoxy? Or epoxy resin with liquid catalyst?


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## ArtMann (Mar 1, 2016)

To answer your question directly, no, CA glue is an entirely different chemistry than epoxy and CA accelerators can't be used to shorten the cure time. Professional grade epoxies can be bought with slow or quick hardeners but none of them are going to be any faster than the 5 minute epoxy you can buy. As someone already mentioned, heat will speed cure time somewhat.


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## NCMau (Jan 30, 2019)

Yes I use the 2 parts A&B and it takes hours before it cures. I am just experimenting to fill a small area with epoxy and color. I built a dam with hot glue but the area to be filled is not flat and the glue would run off.

I need to apply a fairly stiff consistency. I tried this approach unfortunately, I waited too long (few hours) and the glue was too stiff to work. I suppose I could work in two or more stages but it is too time consuming.

So if an accelerator is not available as in CA glue, I guess the 5 min epoxy would be the choice.


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## RichT (Oct 14, 2016)

> I need to apply a fairly stiff consistency.
> 
> - NCMau


That one's easy. Get some silica and add it gradually until you get the consistency you want. You can definitely make it so it will not flow.


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## John Smith_inFL (Dec 15, 2017)

could you expand a little on your project (with some photos) ?
there are several types of epoxy and most have different characteristics.
the biggest difference that I find is structural bonding epoxy and clear casting epoxy or resin.
and you can order what you need with a specific setting time.
you must be aware of the chemistry that some epoxies and resins produce an extreme amount 
of exothermic heat if it is too thick and cures too fast.
I have had some that cured so fast it turned from clear to dark amber, smoked and
cracked in a matter of minutes.
there is a steep learning curve when it comes to materials such as epoxy and resins.
and the old adage of "One Size fits Most" does not apply to these materials.

.

.


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## NCMau (Jan 30, 2019)

I guess the epoxy I am using is called 2 parts clear casting. I just want to fill a burl depression with some color. Again, as I said, this is just an experiment, maybe for a later project.
The idea of using silica sounds good. The one I found SILICA comes in quart tub. Is this what I need?


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## RichT (Oct 14, 2016)

> The one I found SILICA comes in quart tub. Is this what I need?
> 
> - NCMau


Yes it is.


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## ArtMann (Mar 1, 2016)

Extremely fine sanding dust will also work. It can be purchased under the name "wood flour" but it is nothing but fine sanding dust. I have used it straight out of the filter on my random orbital sander. The mix is very often used to glue plywood "stitch and glue" boats together.


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## Bob5103 (Feb 13, 2016)

You can also mix used, dry, coffee grounds, sawdust, etc…, to thicken epoxy.


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## Chenier (Mar 15, 2019)

Epoxy thickeners come with tradeoffs. The first is that none of them are transparent. When mixed into your clear casting epoxy it won't be clear any longer.

The System Three Silica Thickener you refrenced will work very well for thickening your epoxy. It will also make it hard to work, sand or polish after the epoxy has hardened. Silica is rock. You'll need to use a grinder and use a respirator (silica powder is the stuff of miner's lung diseases). But having really hard epoxy may not be a bad thing depending on your applicaiton.

Expanded cellulose powder is a good, easy to work substitue for Silica. It's the stuff disposable diapers are made of, before the baby gets ahold of em. If it's good enough for a baby's bottom… MAS sells it as "Cell-o-Fil". Dunno what the other manufacturers call it.

Wood flour is fine too, but has a coarser texture than expanded cellulose. It's the weapon of choice when circumstances dictate you need to build up something thick and your epoxy has to hold its shape, like putty.

Most epoxy manufacturers sell some type of microballoons. They can be used to bulk up epoxy to good effect and are easy to sand, but they're not as good as thickening agents. They're used as fillers in primer coats.


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## RichT (Oct 14, 2016)

> The System Three Silica Thickener you refrenced will work very well for thickening your epoxy. It will also make it hard to work, sand or polish after the epoxy has hardened. Silica is rock. You ll need to use a grinder and use a respirator (silica powder is the stuff of miner s lung diseases). But having really hard epoxy may not be a bad thing depending on your applicaiton.
> 
> - Chenier


I use silica frequently when filling voids common in mesquite. It doesn't affect the ability to sand the epoxy. It might originate as rock, but it doesn't turn back to one…lol.


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## MrUnix (May 18, 2012)

Talc (aka: baby powder) also works well to thicken epoxy, and most people already have some on hand. And being white makes it easy to add color if desired.

Cheers,
Brad


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## PCDub (Sep 24, 2017)

Baby powder these days is cornstarch, not talc anymore…


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## MrUnix (May 18, 2012)

> Baby powder these days is cornstarch, not talc anymore…
> - PCDub


Yeah, some is… but most is still talc like Johnson's Baby Powder. Just read the ingredient label - should list talc and fragrance only. Cool side effect is that nice scent given off when sanding 

Here is the ingredient list for some Johnson's baby powder we purchased about a month ago (for the grandchildren, not me 










Cheers,
Brad


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## tomsteve (Jan 23, 2015)

> I guess the epoxy I am using is called 2 parts clear casting. I just want to fill a burl depression with some color. Again, as I said, this is just an experiment, maybe for a later project.
> The idea of using silica sounds good. The one I found SILICA comes in quart tub. Is this what I need?
> 
> - NCMau


if you want to add a color to the epoxy then i wouldnt add anything else-just the powedered color. the time that casting resin takes to cure allows air bubbles tro escape. get it curing too quick= bubbles stuck in the epoxy when cured.


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## CaptainKlutz (Apr 23, 2014)

> I guess the epoxy I am using is called 2 parts clear casting. I just want to fill a burl depression with some color. Again, as I said, this is just an experiment, maybe for a later project.
> The idea of using silica sounds good. The one I found SILICA comes in quart tub. Is this what I need?
> 
> - NCMau


1) It's really hard to adjust epoxy cure time, unless you have some polymer formulation experience and cabinet full of curatives; Hence the average person is stuck with what comes out of the bottle(s).

2) Temperature of substrate and environment has huge impact on cure time. Here in 100F AZ summer, 30min epoxy sets in ~10-12 minutes. 5 minute epoxy starts curing just as you are done mixing. Use heat lamp if want faster cure.

3) 'casting' epoxy is intended for applications needing a long slow cure. It produces the least amount of shrinkage, and is for applications with thick cross section. With thick cross section you get significant internal heating; which reduces cure time, causes yellowing, and maybe even shrinkage cracks.

IMHO - you are using the wrong epoxy type for filling small (< 1/2" deep) voids or cracks in lumber. For most wood crack filling applications a regular 30 min cure structural epoxy like System Three T-88 or similar 30 minute cure epoxy would better met your requirements.

If you are adding color to epoxy, filler & dye selection becomes challenging? Any filler is going to lighten the color. You need to use same recipe (weight/volume) of all filler/dye ingredients or the colors will vary between batches. 
Spherical 'glass balloon' silica fillers are most transparent, and lighten the color the least but are more dense Fumed/colloidal silica is less dense, increases viscosity most, but will whiten the color more. Talc or similar mineral fillers will significantly whiten the resin. Wood flour is usually yellow tint and also changes dye colors in resins.

+1 silica filler is one of the most dangerous components used with polymers in home shop. 
Please wear a respirator at all times when handing ram material, or sanding resin filled with silica. You only get one set of lungs. Read this for details: https://en.wikipedia.org/wiki/Silicosis

My recommended epoxy filler in dyed wood applications or painted surfaces for home use is phenolic micro balloons, such as #407 sold by West Systems. They are safer to handle, have a natural red/brown color that is close to aged cherry wood.

YMMV


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## PCDub (Sep 24, 2017)

> Baby powder these days is cornstarch, not talc anymore…
> - PCDub
> 
> Yeah, some is… but most is still talc like Johnson s Baby Powder. Just read the ingredient label - should list talc and fragrance only. Cool side effect is that nice scent given off when sanding
> ...


Whoa! Don't let the grandkids breath it! (i.e., no clouds of powder while diapering!!) Not as dangerous as silica, but still a hazard.


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## NCMau (Jan 30, 2019)

This forum is super. It is a lot more informed than Wikipedia. I will choose my poison soon…. thanks.


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## runswithscissors (Nov 8, 2012)

Don't make the mistake of thinking extra hardener will speed up the cure. The manufacturers formulate specific ratios of resin to hardener, all the way from 1:1 to 5:1 (that's resin to hardener ratio). If the ratios are wrong, you might not get a complete cure at all. Follow their instructions, and measure carefully, and mix the hell out of it. By the way, WEST does offer hardeners with different cure rates, but I don't know if they have a casting resin.


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