Pwk5017

Using Epoxy Correctly

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I finally bit the bullet and bought the west systems epoxy bundle. West systems owes marc some advertising fees for how much i see their products in his videos! After a year of watching him magically repair cracks and knots, I had to have the stuff. I work with a fair amount of non-FAS walnut, and defects are common. I usually mix up a paste of walnut dust and titebond to patch tiny knots/cracks. It works alright, but it dries lighter than the surrounding wood and isn't terribly compelling. It is unfortunate, because the defect areas usually contain the most interest and beauty for me. Now, to put this new product into action on a project. Im currently working on a simple shoe storage+bench for our cramped front entry foyer area. I have saved this offcut on my scrap rack ever since I made an island for a client months ago. I didnt think this client would appreciate a large bark inclusion/walnut shell in their island top and I whacked this 30" piece off the end of the board. The walnut shell impregnated in the board is appealing to me, and the board has some nice figure in that area. I fully expect to have most tell me this piece is garbage, but I want to use it for the top of my bench. Because this area will be on the edge of the bench, I feel the need to stabilize it so it doesn't chip out and flake away over the years. Everything is tight at the moment, but I fear if I don't do anything to it that it will be too brittle for daily use. Here is my question--finally--I generally know how to fill knots with epoxy by watching marc, but how would you treat this defect? Should I tape it off on the edge and fill the whole thing with undyed epoxy? I suppose it would be akin to the mosquito in amber. Will this look like complete crap? Do I carefully infill epoxy/CA glue around the perimeter of the inclusion and leave the void open? Finish will undoubtedly fill the void slightly when I apply it to the piece, but I don't think wipe on poly will offer much structural integrity compared to the destructive nature of my rump twice a day.

 

On regular knot/crack filling, is it necessary to use dye? That dye is terribly expensive for such a tiny bottle. Will coloring with sanding dust work, or do I need to get the dyes to be convincing? I notice in walnut that you probably want the epoxy around a defect to be dark verging on black.

IMG_1770.JPG

IMG_1769.JPG

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Lately I've had good success mixing aniline dye powder with epoxy.  I got 1oz each of few dye colours (lighting walnut, dark walnut, ebony black and a red tint powder). Just a tiny amount added to the epoxy seems to work really well.

I got the powdered dye at LeeValley and put each in small 1.5 oz bottles I got at a craft supply store.  I think what I have will last for years.

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I hesitate to reply because there are other people here with more experience, but we can't make HHH answer everything.

I would normally tint my epoxy black with some India ink (speedball brand).

But that may obscure the walnut husk you're trying to see in the finished project. If your WS epoxy kit is the 105/206 it should be noted that it does not dry completely clear. It has a bit of yellow to it. I think West sells some other resin (209?) which dries more transparent. Also, you will get bubbles in the 105/206 which may be somewhat mitigated by applying light heat during the early part of curing. A hair dryer could work.

It's probably needless to say "Practice on scrap" but I always do.

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So, you're looking to add some wood to your epoxy project?  :)

 

105/207 + graphite powder + light heat...

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I hesitate to reply because there are other people here with more experience, but we can't make HHH answer everything.

I would normally tint my epoxy black with some India ink (speedball brand).

But that may obscure the walnut husk you're trying to see in the finished project. If your WS epoxy kit is the 105/206 it should be noted that it does not dry completely clear. It has a bit of yellow to it. I think West sells some other resin (209?) which dries more transparent. Also, you will get bubbles in the 105/206 which may be somewhat mitigated by applying light heat during the early part of curing. A hair dryer could work.

It's probably needless to say "Practice on scrap" but I always do.

Sorry, I should have clarified which product I purchased. It is the 105/206 combo.

 

Yes, I didn't expect it to be very clear, and this is one of the reasons I was against filling the entire void with epoxy. My plan was to fill in the edges of the problem with epoxy. The red lines in the photo. Then, leave everything blue untreated save for wipe on poly. I guess my question should have been, "will this be sufficient to stabilize the piece, or am I being a fool and the whole thing needs to be encased in epoxy?" Thanks for the india ink endorsement, much better on price! Do you have a mini eye dropper to dispense the ink? I take it the coloration endures?

IMG_1770 diagram.jpg

So, you're looking to add some wood to your epoxy project?  :)

 

105/207 + graphite powder + light heat...

Do you heat the epoxy after you mix and dump it, or do you preheat it prior to mixing? I read the latter somewhere. Also, will this graphite work?http://www.amazon.com/Generals-Powdered-Graphite-6-oz/dp/B00TCLCO7A

 

I assume that isn't such a specialized product, and that graphite powder is graphite powder. Would graphite be easier to work with than india ink?

 

And it's not THAT much epoxy! The project will be atleast 98% wood :P. It is a great project to build my goo skillz, or build an immediate allergic reaction to the stuff. I already have my gloves ready for mixing, but do you need to worry about fumes? Also, better to scrape/plane it away compared to sanding, correct? The warnings concerned with epoxy exposure kind of scare the hell out of me.

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==>whole thing needs to be encased in epoxy?

Yes.

 

==>105/206 combo

Never used it for filling. Since you're tinting w/ graphite, probably not too bad... Bubbles will be your big issue.

 

==>heat the epoxy after you mix

Yes.

 

==>and dump it

Yes. and heat general wood area to improve absorption. Small amount of heat only.

 

==>better to scrape/plane it away

Yes. Card scraper.

 

==>warnings concerned with epoxy exposure kind of scare the hell out of me

Wear disposable gloves --- and don't drink it...

 

==>graphite be easier to work with than india ink?

Yes.

 

==>will this graphite work?

Yes. Maybe 1oz for the entire project. A little graphite goes a long way...

 

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I am not an expert with epoxy, but when I've used West Systems it's pretty thin.  I think a very thin coat, untinted, would seep into the wood and help seal the area and provide some strength.  

I haven't used graphite, but India ink works, just use an eye dropper or something similar to control the amount (I've learned not to try just tilting the bottle). I have also had good luck with Cushing Direct Dye that I bought at the craft store.  It was only $3.95 a bottle, they are small bottles, and works to color the epoxy.  My only complaint with the Cushing was that turquoise in a deep knot hole just looked black when it cured. 

A random orbit sander, with no sandpaper on-just the bare pad-pressed near the crack after the epoxy is applied can help bring bubbles up to the surface and popped. 

Good luck, it should look great.

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If you sometimes need black epoxy, I use golf club epoxy, which comes in black, and I keep it on hand for working on golf clubs.  It bonds fine to wood too.  It is pure black though.  I have mixed some with Walnut sawdust for very small holes in knots, but it would take some practice to get good results with a hole that big.  I'd maybe try stirring some in with the West, but not make it a complete mix, as in to leave some "grain".

http://www.golfworks.com/product.asp_Q_pn_E_EPX1_A_cn_E_33

That's where I bought the gun to mix the duo tubes too.  Anything with their store brand name on it is good stuff.

Their wipes work like magic.    http://www.golfworks.com/product.asp_Q_pn_E_VB1015_A_cn_E_33

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Metallic powders work wel for coloring epoxy, also. You local Hobby Lobby or Michael's craft store will probably have some silver, gold, and copper colored powders. An advantage of powders over liquid colorants is that they don't affect the curing process. I tried a paint pigment once, and it colored well, but never fully hardened. Working at a steel mill, I have access to fine mill scale dust, which produced a nice jet black color, similar to graphite. Regarding the heat, a little goes a long way. Too much hot air will thin the epoxy to a watery consistency. Not sure if it will affect curing.

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Neat piece of wood. I would definately epoxy the whole thing and taper back to the wood, right after the bark. I like the 105/206 w/o a filler/tint as it is clear and imo, looks better. Don't forget to damn the sides and bottom. Good luck.

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Well, that is nothing short of shocking how the epoxy sucks into the wood. I mixed a double pump with a bit of walnut powder to give it a brown tint and dumped it on my trouble areas then did the orbital sander and a hair dryer for a bit. I then called it quits and went to cut the plywood for the shoe compartments. 45 mins later and the epoxy somehow found every possible nook and cranny courtesy of gravity. I will need to apply a second batch to fill in the areas that sunk below the surface. I might flip it tomorrow and hit the defects on the underside(ironically the bottom is mostly clear compared to the top) and then hit the top again on Thursday. 

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That's cool, and that's the way it works. Make take 3 apps. When you get to the one that you think will be the last, apply the heat. And then on the next one as well.

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Soooo what do you do when the epoxy is still gooey in places after 72 hours? I assume that's NOT how it's supposed to work?

 

not sure I'm in love with this $150 purchase. 

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==>^^^

In practical terms, there are only two reasons for this... Well, really only one: RTFM... :)

Incorrect mixing ratio (using 5:1 pump for a 3:1 mix, vice versa). This is rare because, at some point, West changed 5:1 and 3:1 threading so it's much harder to use the wrong pump... Far more likely: you didn't prime the pumps correctly and dispensed the incorrect amount for one (or both) components... Epoxy is not like solvent finishes where 'close is good-enough'... For small amounts, you should dispense by weight...

Note: 5:1 ratio is by weight and volume... 3:1 is by volume and 3.5:1 by weight...

Insufficient mixing of hardener to resin -- you dispensed the correct amounts, but didn't mix the components thoroughly... I've done this once. The mix took a lot longer to cure, but it eventually did...

There are other reasons, but they would be so rare as to not worth considering... Well one maybe... Extreme low temps can extend cure times... But you're in PA, not Alaska...

Verify which of these two happened, then call West's technical support -- they are excellent...

Since it's a non-structural application, I suspect they will tell you to wait a few more days and see what happens...

 

Edited by hhh
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I did three separate applications and the first two cured after a few hours, is the open time really 2ish hours? Granted, they were 1/4"+ pours, so I can see how that would remain gooey for several hours. This last one was overtop a 72 hour old pour and parts of it hardened just fine, but a few patches did not. My basement shop is probably 55° right about now. I taped off all vents and cold air returns in the basement, so it is usually below 60 most of winter.

 

I will see what their technical support has to say, but I am impatient and will probably take a junk chisel to it tonight and send it through the drum sander. Time to finish this short build and get on to the next one.

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==>is the open time really 2ish hours?

Unless you're using 209, no...  What are you using? If it's not 209, then it's improper ratios...

 

==>overtop a 72 hour old pour

While that's not your problem, structural pores must all be within 24hrs...

 

==>usually below 60 most of winter

Would only cause a problem [maybe] with 209... But I'm pretty sure I've used 209 down to 40F -- I'm sure that's not recommended...

<edit> just confirmed with tech support... 209 has problems curing below 70F and 207 below 60F...

 

==>parts of it hardened just fine, but a few patches did not

That usually means improper mixing... The mix must be stirred/folded completely before use. I'm not sure, but if you added heat to thin the mix, you may have over-heated it and caused inconsistent cross-linking... If you use heat, use it very sparingly.

 

West has an extensive application note, video and techniques library -- hundreds of items... You may want to review your procedures:http://www.westsystem.com/ss/how-to-use/

 

 

==>I am impatient

Could be a problem... The dispensing and mixing should be done with some attention to detail... Again, it's not like solvent finishes where thinning 30% could mean anything from 20% to 50% and get similar results... You can't 'wing-it' with epoxy: http://www.westsystem.com/ss/dispensing-and-mixing/

 

Edited by hhh

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I have recently been looking into epoxy (have some knots to fill and a complicated glue up).  I was looking for the strength comparison between 206 and 207.  The difference isn't applicable to furniture stresses :http://www.westsystem.com/ss/typical-physical-properties/

Is there any reason (other than cost) to not use 207 for everything?

In doing so I found the datasheets.  The datasheets specify that 1:3 and 1:5 ratios are by volume, and not by weight (which makes sense since the pumps are a specific volume).  The datasheets do contain the ideal weight ratio (for 207 its 3.64) and and acceptable range (3.41-4.16).  http://www.westsystem.com/ss/assets/Product-Data-PDFs/TDS 105_207.pdf

I think for my purposes I will probably need more than 1 pump, but I do see uses for smaller amounts.  

hhh have you tried both weight and volume?  Which had better success? Or maybe that was a typo (unfortunately ounces are both weight 16 oz=1 lb  and volume 32 oz=1 quart in the US)

 

Edited by skiback46

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From the spec sheets there is no real difference (206 vs 207) in pot life (20-25 vs 22-26 min) or thin film working time (90-110 vs 110-120)

With the benefit to 207 being clear and reduced blush and anecdotaly less bubbles

 

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==>hhh have you tried both weight and volume?

Ahhh, a mystery... I love mysteries... :)

After getting off the phone with Gougeon's tech support, I'm going to have to date myself... :)

Today, it's by volume. But when I started using Gougeon's 105 system (before it was branded West Systems), it was by weight... The difference is very minor and since I use the bulk dispenser, I never experienced any change at all...

105/205/206 is 5:1 by weight and volume...

105/207/209 is 3:1 by volume and 3.5:1 by weight...

Unless you are using the bulk dispenser, Gougeon recommends dispensing by weight for small volumes -- the 300 series pumps are not accurate for small volume dispensing... I'll update the info above...

 

==>not use 207 for everything?

Cure temps: 209 shop must be above 70F; 207 must be above 60F. Other than that, 207 is great for everything -- only about twice as expensive... :)

 

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