Questions on thinning epoxy

C Craft

Well-Known Member
Questions on thinning epoxy is just what this thread is about?? I am in no way trying start some new version of "glue wars" so lets not got there!

However to set this scenario up that gets us too the question, it is a little long on story. :nothing: So bear with me as it takes a little explanation to get to the question. I often use a two part epoxy that has been thinned to get it to flow into and area that may be too hard to get un-thinned epoxy to fill completely.

So I am building a new tube to be used in etching blades. In an effort to have it not turn over in the shop I took the cap that will be on the tube and cut a circle out of a piece of wood about 6"W X 12"L. Since the pipe was schedule 80 pipe I then drilled some holes into the cap but not all the way thru and imbedded some short metal screws into the cap as well as the wood. Kind of a cross anchoring system for that cap of the pipe that will make up this tube.

Then I mixed up some two part epoxy, (it is a brand that I normally use) I then added my standard thinning agent, (ACETONE)

Any time I have some little project like this going on I experiment with different things that I might incorporate in the making of a knife.

I decided that I needed more epoxy to completely get the scews covered and offering a tighter bond to the base. So while at Wallyworld yesterday I picked up some more two part epoxy. However this is a different brand than what I normally use. So when I get home I mix it just like I always have and thin with the ACETONE!

Immediately I noticed that that this two part epoxy did not seem to like the ACETONE as a thinner. Even though it did thin it somewhat I could not get mixed well into the two part epoxy and after drying it seems to have a spider web present in the dried product!

So here is the questions.

What do use to thin two part epoxy??

Does it need to be brand specific??

Any thoughts or comments on thinning epoxy is welcomed. Thinning epoxy with acetone is something that I have done before and have never had any adverse results such as the spider web look, or strength loss, etc. etc. but I have never tried it with this two part epoxy!
 
Cliff - acetone is a "generic" thinner for epoxy and works for many types of epoxy. There have been studies that show a loss of strength, depending on how much thinned. There could well be some 2 part epoxies that don't like acetone for thinner, and it looks like you've found one. Raka.com is where I normally purchased most of my epoxy - about same thing as West and was a good bit less expensive when I was boating.

Check this link for a full explanation of thinning by West Systems: http://www.westsystem.com/ss/thinning-west-system-epoxy/

A couple of points from the article:

1. For a variety of reasons, fast evaporating lacquer thinner appears to be more appropriate for thinning purposes than acetone or alcohol. (Raka.com says denatured alcohol at no more thn 5% is best - I've used both acetone and alcohol)
2. adding 5% lacquer thinner makes about a 60% reduction in viscosity"
3. adding 5% lacquer thinner to epoxy reduces the epoxy’s compressive strength by 35%

Cliff, now you know more than I know about thinning epoxies {g}.

Ken H>
 
Thanks Ken, I didn't name the two part epoxy cause I didn't want to get into the whole "glue wars" thing but this two part epoxy, definitely did not like the acetone. For what I was doing which was adding some redundancy to the bond, it will work fine. I know a lot of guys have switched to this brand but I also the other brand I use quite often I have thinned with acetone before and my destruction tests show no loss of strength. In fact the acetone seems to evaporate out as best as I can tell.

I have been thinking of making a switch to the West System and the thought of paying that much and then having a mess like that if I need to thin it. Well lets just say I am glad I experimented with something other than a knife. The spider web effect might have not looked too pretty in a epoxy over some file work!:what!:

I will set down and read the info on the West System and thinning! Thanks for the link.
 
Cliff - I understand completely your concern about starting "glue wars". Just remember, because an item is calling "epoxy" doesn't mean it's the same composition as the traditional epoxies like West System or RAKA epoxy. Just because "brand x" epoxy doesn't like acetone (or perhaps any other thinner) doesn't mean it's not a GREAT epoxy for knife handles. I'm using the G-Flex epoxy for handles now due to the great reviews it had from knife makers I really trust. I never had any problems with the RAKA epoxy I'd been using either, but it was starting to get sorta old and I needed fresh, so rather than ordering another couple quarts of RAKA, I ordered G-Flex. So far, so good.

Ken H>
 
Since you don't want to get into brand names I'll just say that the company I buy my epoxy from offers a thinner specifically for that product. If you would care to know the product just PM or call me.
 
Ken which West System are you using the 650-8 G/flex Epoxy or the 655-8 G/Flex Thickened Epoxy Adhesive. After reading the info from your link, http://www.westsystem.com/ss/g-flex-epoxy/

Their are several things that catches my eye about this one 655-8G/Flex Thickened Epoxy Adhesive!

A toughened, versatile epoxy that is conveniently prethickened for permanent waterproof bonding of plastic, fiberglass, ceramics, metals, damp and difficult-to-bond woods. With a modulus of elasticity of 150,000 PSI, it is a bit more flexible than standard epoxies and polyester, but much stiffer than adhesive sealants. This gives G/flex 655 the ability to make structural bonds that can absorb the stress of expansion, contraction, shock and vibration. It is ideal for bonding dissimilar materials. Mixed at a 1:1 ratio, G/flex 655 gives you 45 minutes of working time at room temperature. It reaches an initial cure in 7 to 10 hrs and full cure in 24 hrs.

That one may be worth checking out. For a use that didn't require thinning it sounds like the all around best of all worlds.

Darren, their is PM inbound!

EDIT: I just went back and re-read the info on the 650-8 G/flex Epoxy again and it has pretty much the same bio, except it doesn't have the thick thing listed. So now I am confused it seems they are about the same thing but the 655-8 G/Flex Thickened Epoxy Adhesive is much thicker. So....................... I got to give this some more thought!:s12202:isn't anything easy anymore!:biggrin:
 
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Cliff I've been using the 650 for 2.5 years, tested it till I couldn't think of another test. It has worked like a charm. When I need thinner epoxy I use the West Systems 105 with either the normal hardener or the slower one depending on the time I feel I need to work my project. Their products in my case is worth the little extra cost. South Florida humidity can be a pain when it comes to drying epoxy. Their stuff always dries the same. It's also easy to add color to if you feel the need.
 
Thanks to everyone who has responded to this thread! I have inquires out in several different directions to manufactures. So waiting to hear back from them as well. I definitely don't want anything to do with the one that spider webbed on me. So got to look at all the info and then going to throw my hat in one of the rings!:happy:

Darrin, thanks for the PM the info you have given also give me more to consider!

George the more I look into the West System the more info I read and the more I lean that direction. I know what you mean about the humidity here in Fl.!! How ever I don't use a lot at one time being a part time maker. I am concerned about buying a quart at a time. So for those that use the West System I got a question. How does the West System do on storage? Has it got a decent shelf life after opening???
 
Yep, the specs on the GFlex 650 and 655 are confusing and read the same, except for the "thicken" part. I'm "assuming" (we all know ass-u-me) the only difference is the 655 has a thickening agent like fumed silca (such as Cab-O-Sil) added to the epoxy for thickening. Since I've got a 5 gal bucket of Cab-O-Sil, I just use the 650, and if I need it thicken I'll add a tad of Cab-O-Sil to thicken. If I need thinner, I'll use RAKA and thin it a bit.

Ken
 
Hey Ken I got a email from the maker of the epoxy I was using today and here is what they had to say about acetone as a thinner! The reason for the package change is that the company that makes it has been bought out by another company, ITW Polymers Adhesives North America, they also have Permatex and a couple of others. It is just amazing who owns who anymore!!!

Clifton; Acetone or alcohol is OK for thinning, but does need to flash off before it cures, so not good in between substrates. What I do is warm the epoxy by putting it on a radiator or a warm area. This thins it out but also cuts down on the open/work time. Either way this won’t compromise the strength.

Steve Leslie
Senior Technical Service Representative
ITW Polymers Adhesives North America
 
Cliff, that's a good heads up - I'd not thought about the scales preventing the acetone from "flashing off". I knew that's how thinning worked, but the years of epoxy work I've done was always on boat stuff and the thinner solvent could always flash off. With a handle scale clamped, that surely work cause a problem. I don't thin epoxy for gluing scales on, I might add a tad of thickening agent, but never thinning there. Thinning is used when I'm trying to fill cracks, get epoxy to soak in, etc.

Thanks for the heads up there.

Ken H>
 
I've found that epoxy flows much better when it is warm (it also sets up faster). Perhaps it could be heated to maybe 120 degrees....
 
I've found that epoxy flows much better when it is warm (it also sets up faster). Perhaps it could be heated to maybe 120 degrees....

That was pretty much the techs summation but, he didn't go on to give a temp to work by, or a cut off point at which it flashes. I know from experience it will reach that flash point in the drying if heated.


Case in point, I am working on something in the shop one night and it is kind of cool. So I was warming the epoxy to get it to thin up where I could flow it into an area where it had a small opening to enter. I had mixed in a small plastic container. Because of the cool and I wanted it to flow like water when I poured it , I kept going back to the container I had the already mixed epoxy in and warming it with my heat gun. I had a small pair of vice grips clamped to the container, so I wasn't really feeling the heat my self.

I got the last of what I was doing to lined up and ready for the epoxy and...............................when I picked up the container it was already went from thin like water a couple of minutes before that to setting up. I couldn't use it had to start all over. The continual warming off and on with the heat gun of the mixed epoxy had made it reach its flash temp, and a 30 min, working time epoxy had gone from mixing to set all in about 5-7min, from the minute I mixed initially to the last time I laid down the heat gun and reached for the epoxy to use it. :what!:

Well I'll be a monkey's uncle, :steve: I learned too much heat is not a good thing unless you want to move up the working time!! Note to self too much heat Baaaaaaaaaaaad!!!!:13: :biggrin:


EDIT:
Can anyone that uses the West System G Flex, if you buy quarts how long a shelf life does it have after opening?????

How quick do you use up the quarts?? I have a concern with it going bad before I can use it all buying the quarts!!
 
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Cliff, if you're just using it for knife handles, a qt (16 oz each part?) would make several hundred knives for sure. Shelf life is hard to determine with epoxy - depends on temperature stored at, and kept in dark? A good guide, is how long does epoxy normal last for you on the shelf?

Ken H>
 
When I warm my epoxy I put the containers in hot water...before mixing...epoxy seems to warm up or get hot right when it starts to set so you have to have all your ducks in a row when you start mixing if you warmed it up. in my opinion your playing with the devil trying to thin it but I don't know, I've never tried it.
 
When I warm my epoxy I put the containers in hot water...before mixing...epoxy seems to warm up or get hot right when it starts to set so you have to have all your ducks in a row when you start mixing if you warmed it up. in my opinion your playing with the devil trying to thin it but I don't know, I've never tried it.

Bladegrinder:
I think the heat gun I was referring too was too much heat and I had never tried heating it like that before. When it took me a while to get everything I was preparing to glue ready it was too much heat and about two too many cycles of heating. I learned what not to do!:what!:
I think thinning has to do with the epoxy. I posted earlier what the tech said about thinning with acetone or alcohol, but here it is again if you missed it. The one thing he did warn of was, " Acetone or alcohol is OK for thinning, but does need to flash off before it cures, so not good in between substrates." I have only used it thinned on a knife one time and have had no adverse results! But I have used it several times thinned for other projects and had no adverse effects with it!

However as KenH stated not all two part epoxies are the same. That is kind of what sent me on this quest. The one I picked up to glue the pipe cap I referenced definitely did not like acetone as a thinner and in this case it was used in a place where it could flash off, and when dried it still left spiderweb like areas in the dried epoxy!

Ken, thanks for the reference to what I was using Vs the West System. Using that comparison it would probably behoove me to buy it in the smaller bottles. I know from experience not to use epoxy that is too old! Being a part timer I do not do enough to use up quarts fast enough I am afraid!
 
I bought the 8oz gflex (2 bottles, 4oz each), and I should be good for a year at my slow pace.... I love this stuff by the way, I've done some experiments/tests and like how it preforms. It has a 45 minute work time at room temperature, which is more than enough time for me, what I'd like to know is just how much higher temps affect the work time... I may give the techs a email or call, if I find out anything useful I'll report back here.

This is important to me, I make mostly hidden tang knives, it is vital that the cavity in the handle be completely filled with epoxy and tang, and a thin, watery consistency to the epoxy makes this much easier to achieve.
 
George, contact West System and get some piece of mind as what to use as a thinner for their specific product, (G flex is not what I have been using)! I am doing a little research before I jump into another epoxy. If you find out the info please post it or at least shoot me a PM, as I would like to know, because I am beginning to lean towards making G Flex my new epoxy.

I will tell you something that will help with a hidden tang knife. Next time you go out for coffee pick you up a handful of stir sticks. You know the ones that look like a small straw.I cant remember who it is that has them but they look almost flat but are open like a straw. Poke one down in there while filling. The tiny straw lets the air go out the top, (no air pockets to worry about forming). For added insurance puddle the stick up and down every so often,and as you remove the straw continue to use that puddling action, (it is like puddling concrete to get it to fill a form completely)!!! It serves the exact same purpose as it does when you do it to concrete!


EDIT:


For what it is worth I contacted a rep for West Systems, about their epoxy and here is the info that is pertinent to this conversation. I asked them about thinning with a solvent or another agent, which they side stepped but did indirectly address that and, the rest is informative for anyone using West Systems or thinking about using it.

Many custom knife makers use G/flex 650 (honey like liquid) and G/flex 655 (like gelled toothpaste) to assemble their knives. The only complaint in 8 years I can recall was from a knife builder (a seasoned builder that had used G/flex successfully for a couple years) who used a contaminated rag and solvent to clean the surfaces to be glued before applying epoxy. I convinced him to try it again but by using plain white paper towels to apply and wipe off solvent instead. He called back and said it worked although he struggled initially to believe that the rag could be the problem. Even recently laundered rags can cause problems because of residue from fabric softeners, from furniture polish or from auto wax residues that the detergent failed to fully remove.
If you mix small batches that are applied quickly at 72°F, you will have well over an hour to assemble the pieces before clamping the assembly. Maximum adhesion is achieved after 24 hours of cure while clamps off cure time for light use would be after 4 to 6 hours at 72°F. Large volumes of mixed epoxy left in the cup cure faster than small batches. You can extend working time by pouring the epoxy into a wide shallow pan or larger mixing pot to increase exposed surface area and slow the cure and gain working time. Here’s a link to more information: http://www.westsystem.com/ss/g-flex-epoxy/. Please feel free to call or email with questions.
Regards,

Thomas Pawlak | Technical Service
Gougeon Brothers, Inc.
 
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