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Options for Epoxy Void Fills

M

Mark Jundanian

Joined
Jun 6, 2018
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Location
La Grange, IL
This bark inclusion was completely buried deep within this large piece of walnut so it was a complete surprise (but then so were the two nails and the bullet). Now that I have discovered it I find that it will be through and through when I turn the piece around and hollow out, so I'm thinking of filling it.
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This will be my first epoxy fill, and as I'd like to be able to move on with the making I'm hoping to do the fill tonight or tomorrow. The cavity is pretty deep as presently revealed. My plan is to fill the cavity now from the outside before hollowing so the epoxy will be contained. I still have a tiny bit of outside turning to do which should be enough to shape and smooth the outer surface of the epoxy.

I have reviewed several previous threads that I found with a search for 'epoxy fill' and I have a few questions. I don't have the time to acquire West Systems or any of the fancy brands, so think in terms of the products you can get at the typical AceValue hardware store.

What are the relative merits of 5 minute vs 30 minute epoxy? I've seen people using both.
Clear epoxy vs. epoxy mixed with coffee grounds, vs epoxy mixed with sawdust?
If coffee grounds, I'm assuming fresh, not used?
If sawdust I'm assuming the finer the better?
How much material would you need to mix up with the epoxy for the colored slurry?
 
I'm curious about this also and would like to hear more experiences with simple solutions for saving a project when you run into this type of thing.
I just set a bowl aside for now because I ran into several cracks/voids in the bottom of the bowl that weren't visible from the outside.
Does the typical hardware store epoxy flow well enough to fill a void with small pockets like that or will it sit on top and leave you with bubbles?

If mixing anything in the epoxy, I would think the slowest stuff would be best so you have plenty of work time before it thickens.
 
I have never had a problem with off the shelf epoxy for filling small voids nor with the quick setting versions if they allow time to mix and apply. I mix with a variety of fillers depending on the effect I want, including screened wood dust, carbon powder, coffee grounds, and brass key filings. (With the latter, I use a magnet to separate out all of the steel filings I can.)
 
The slow set is best for mixing other material into the epoxy.....especially if you're using a re-usable artist's palette knife. (ask me how I know that! :eek:)

You can also use the RIT fabric dye available at the supermarket. I'm using the brown color.....the more you add, the darker brown it gets.

You can use cloth hockey tape for applying directly over the patch of epoxy. The hockey tape doesn't stick to the dried epoxy, so easy to separate, once the epoxy hardens. (Since you asked about easy to find items locally, I believe the hockey tape is very similar to first aid bandage tape.)

-----odie-----

.
 
B5185_88.JPG Repeat repeat, rather then spend a lot of time trying to keep epoxy in the void I use epoxy putty to completely fill voids and sometimes rebuild an edge. The putty stays in place and the excess can be turned off then I undercut up to a 1/16" deep and refill with crushed stone and CA. The 4 mesquite burl bowls in the picture were done that way and filled with turquoise.
 
Don Wattenhofer said:
View attachment 35074 Repeat repeat, rather then spend a lot of time trying to keep epoxy in the void I use epoxy putty to completely fill voids and sometimes rebuild an edge. The putty stays in place and the excess can be turned off then I undercut up to a 1/16" deep and refill with crushed stone and CA. The 4 mesquite burl bowls in the picture were done that way and filled with turquoise.
Click to expand...

Howdy, Don........Are you adding any color to the epoxy putty? .....or, is the putty completely hidden in those bowls?

Thx

-----odie-----
 
Used coffee grounds and 5 minute epoxy for me. I use blue tape to build a dam, and bamboo skewers to mix and spread around. Never had a problem with the epoxy kicking too fast. Fresh coffee grounds are very uniform in color. Used grounds have a more varied natural color and that doesn't look too much like plastic. I've also used brown dry Rit dye particles.
 
You know, @Mark Jundanian .......I think the coffee grounds and putty suggestions would be better for your huge void, than what I suggested a few posts ago. Straight epoxy works well for filling cracks and small voids......not big ones, like what you've got. No matter how you decide to fill it, you're going to deal with the same issues on the interior. It looks to me like you kept removing material, thinking you'd get rid of the bark inclusion.......I know, because I've come up with some similar shapes, doing just that! o_O

I've never been a fan of "unnatural" looking fills, like turquoise, and resins, etc.....but, that's just me. I know others like the look much more than I do. They are encouraged to do what turns their crank......and not listen to opinionated old guys, like me! :D

Now, if it were up to me, I'd just cut my losses on that one, and go on to the next project. (What......is that opinionated old guy still flapping his jaws? :eek:)......but, if you decide to finish it, be sure to find this thread later on, and show us what you came up with.

-----odie-----
 
I just use regular 2-part epoxy and very fine charcoal dust (all the rage for mixing with foods and brushing your teeth with it, if you can believe that). It's a mess (like dancing with the devil's daughter sort of mess!) but it looks great when you are done...
 
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I personally (usually) prefer a fill like that in black. I mix up epoxy and add a drop or two of India ink. Whatever you use, just mix in a bit at a time till it "seems right" or "looks right".

I've had good results with the 30min stuff you can get from the hardware store.

You probably aren't going to get it all filled in one go. I'd just plan from the outset on having to do several layers. Mainly because it's hard to get it down in all the cracks if you try to fill it all at once, and sure enough you'll cut into a big void and have to re-fill that. At least that's been my experience. Starting the fill from the outside is not a bad idea, but I'd then rough out the inside and fill from that side next.

Although to be honest, if it was my bowl, I'd probably rough out the whole thing (inside and out) and re-evaluate. Sometimes leaving a void like that adds to the look of the piece (assuming it doesn't take away too much from the potential function).
 
Well thanks all for the quick and considered responses. Odie, that is the shape I was intending to make. When I came into the defect I had hoped it would get smaller as I went. Instead it seems to have gotten bigger. So you're part right.

I have been stabilizing the inclusion with CA as I've gone along, but I've still lost a bit of the bark from the tailstock side of the defect. It's hard to see the remaining black bark in the shaddows at the bottom of the hole, but the defect is probably 1/4" deep with some 1/2" deep crannies and crevices. What I predict is that when I hollow out the piece to 1/4" I will loose the bark that is now on the bottom of the defect. I would like to preserve this remaining bark hence the epoxy from the outside. I don't think it will be too deep to fill in one go, but I have been cautioned to be aware.

As to putty, I don't think that will fill in the crevices as well as liquid will and I prefer a fill that has some translucency. Which gets to another question. It appears everyone prefers to mix in a colored material. I know in a previous thread @Bill Boehme said that he uses clear, no other takers for clear?

I should have given dimensions earier. The whole knot is about 2" in diam. The hole is about 1 1/4" x 1/2".
 
Be on the look out for bubbles in a large fill like that. If adding something like coffee grounds, ground up bark, sawdust etc it might not be as big a concern but I've had them slowly creep up as the epoxy sets and then create a crater on the surface when they pop and too late to fix other than another fill. A heat gun helps eliminate them as the epoxy sets.
 
odie said:
Howdy, Don........Are you adding any color to the epoxy putty? .....or, is the putty completely hidden in those bowls?

Thx

-----odie-----
Click to expand...
I have never tried to color the epoxy putty so yes the putty is completely hidden. I borrowed from Stephen Hatchers method of doing designs on turnings where he marks the design in pencil on the turning then undercuts the designs and fills with crushed stone. The only difference is that you undercut the putty instead of the design. This pic is an example of what i learned from Stephen - I scanned a hop leaf then shrunk it to 3 different sizes then with carbon paper between the leaf pic and the turning I traced around the edges of the leaf. The undercutting the design verses the putty is no different.
URN112a.JPG
 
odie said:
I've never been a fan of "unnatural" looking fills, like turquoise, and resins, etc.....but, that's just me. I know others like the look much more than I do. They are encouraged to do what turns their crank......and not listen to opinionated old guys, like me!
Click to expand...
I agree with you Odie: Jeff Foxworthy so eloquently asked the question, “Have you ever seen glitter paint on a yacht?”
 
Maybe too late for your use this time, but here goes. For fills like this, I use bar top epoxy and tint with trans tint dye. Takes very little dye.

This epoxy is very thin and can take 24 hours to cure. Because it is so thin, it will seep into very small areas and give much more complete "fill" compared to quicker setting proxies. Because it seeps into small openings, it will release bubbles that you need to pop with a lighter or torch so you don't have surface bubbles.

Because it is so thin, bubbles formed during mixing quickly dissipate and you are left with a very clear, clean fill (if not using a filler).

Bad part of this type epoxy is it will run all over the place if not dammed in, and it will seep through very small cracks and onto the lathe or bench if cracks go all the way through a piece. I use foil tape on the bottom of cracks and use hot glue to form a dam.
 
Rather than the bartop epoxy, you can simply warm up regular epoxy and it will be thinner, but otherwise perform as usual, except for flowing and filling better.

In the microwave prior to mixing, 10-15 seconds is all it takes. You can also warm up in hot water, if you're patient. When you take it out of the microwave, it should be warm but not hot. If it's hot, dawdle your way back to the shop.

When you go to mix, it will come out syrupy to watery, so it's harder to measure. You will also want to make a little bowl out of some aluminum foil or use a solo cup for mixing. The epoxy will set up a little faster than usual.
 
Mark, you can sometimes just peel it off with your hand, but sometimes, it really sticks and can tear wood fibers. I've also used a bench chisel to get it started, or just shave it off while turning.

I'm not home right now, so can't check the brand, but it's the one that Menards sells. A pint bottle each of hardener and resin for $20-30.

The mix is 50:50 and I use cheap 30 ml graduated medicine cups for mixing. The cups are much cheaper at Amazon than those sold at woodworking stores.
 
You can remove hot melt glue by soaking it with denatured alcohol. If you use a chisel, you can make big scratches, trust me on that one. To get rid of bubbles in epoxy lightly hod the flame of a torch over the spot, bubbles disappear like magic. The hardware stores now keep the torches locked up, they told me druggies, meth users were stealing them to heat up the meth , cook it or something like that.
 
Mark Jundanian said:
I know in a previous thread @Bill Boehme said that he uses clear, no other takers for clear?
Click to expand...

Yep.....I also use clear quite a bit. it works very well for small cracks, and sorta absorbs the surrounding color to camouflage it pretty well.

-----odie-----
 
Another way to get the bubbles out of epoxy is a trick rod builders use. Take a straw, or even better a plastic coffee stirrer from a fast food place, and blow on the surface of the epoxy. Exactly why this works so well is a little mysterious, but the bubbles pop or disappear.
 
Dean Center said:
Another way to get the bubbles out of epoxy is a trick rod builders use. Take a straw, or even better a plastic coffee stirrer from a fast food place, and blow on the surface of the epoxy. Exactly why this works so well is a little mysterious, but the bubbles pop or disappear.
Click to expand...

Hot rod builders are full of hot air, obviously!
 
Well I went for it. Just finished the pour. I've been around the block several times today over how I would do it, but in the end I've pretty much followed Tim Connell's suggestions. Hot melt dam and the low viscosity bar top epoxy mixed with used coffee grounds.

Getting set up was a bit of a trick. I wanted to position the defect so I could pour into it, but that requires holding the piece on an angle. One of those flexible carving stands like Trent Bosch sells would be ideal. I don't have one, but I do have a tilting table on my drill press.
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Next challenge was to build the hot melt damn. That was a little more combersome than I was thinking in part, due to the saddle shape, the walls had to be rather tall, and because I was clumsy with the glue gun. I should have given myself a little more clearance around the defect, too. I almost dumped some hot melt into the cavity.
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Then mixed up the epoxy, which is Famowood Glaze Coat.
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The pour went well as far as I can tell. I used a heat gun sparingly to pop the bubbles, because I realized that the cure is also exothermic and the hot melt was starting to soften.

One downside is that Glaze Coat instructions say full cure is 72 hours :eek::(. So nothing to do for a while. @Tim Connell do you wait the full 72 before turning?
 
Instead of a heat gun or propane torch, I use a little Ronson jet lighter (refillable butane) that I find in the checkout lanes at Wally World for less than 5 bucks. With a smaller flame, it is easier to direct the heat.

Most of what I fill usually is a rough turned object that just goes back on a shelf until I feel like turning it. I've not played with time/temp and machineability, but if your plan is to finish turn, sand and finish right away, I would lean towards following the 72 hours, at least for final sanding and finishing. If you still have the mixing cup with a little epoxy left in it, you can use that to test for hardness and sandability.

I did have one bowl with some epoxy fills that I know I turned sooner than 72 hours, but if my memory is correct, it seemed to be slightly "soft" after final turning, so I let it sit for another day before sanding/finishing.

You can decrease the cure time somewhat with increased temps. Not suggesting baking it in the oven, but if you have some place it could sit that would be 80° or a little higher, would shorten the cure time, although that might be tough with the temps we're supposed to have the next couple of days.

Edit, good use of the tilt table for holding the piece, I've used all kinds of "props" to hold wood at funky angles for epoxy pours. The hot glue also works to help hold blanks at funny angles.
 
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I wasn't sure what to expect when I started to turn the piece after the epoxy cured. I was assuming the epoxy would be quite hard, but in fact it offered very little rseistance.
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After final contouring I sanded up to P1200. Here it is with a bit of mineral spirits.
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The epoxy fill is not nearly as smooth as the surrounding wood, but I think this reflects the coffee grounds, which don't really sand well. It looks better under the MS and presumably it will look and feel better under a few coats of finish, as well.

I have a few air bubbles, which were not apparent after the cure. Apparently these were under the surface and revealed when the upper layer of epoxy was turned away. Not sure how these might have been avoided.
 
I usually will do another coat (clear should be ok) to fill air bubbles like that. Use a squeegee to push it into the holes (I use a rubber spatula I rescued from the kitchen). Just need a skim-coat to fill the holes - a thicker epoxy is good for this, so it doesn't run all over. A thin coat and you don't need to re-turn, just sand down the extra epoxy in that area.
 
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