thinning Two part epoxy

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Pignut

Bushcrafter (boy, I've got a lot to say!)
Jun 9, 2005
4,096
12
45
Lincolnshire
Is it possible to thin down two part epoxy and not effect its setting ability?

Need it to be quite runny to allow it to soak into a fabric
 

scanker

Bushcrafter (boy, I've got a lot to say!)
Aug 15, 2005
2,326
24
52
Cardiff, South Wales
Can you heat it at all? I've been using Araldite Precision and usually stir it for a while under a lamp before using it, which makes it a lot more fluid. There's a long thread on BB about making homemade micarta which might have some more information of use to you.
 

stevec

Full Member
Oct 30, 2003
548
144
Sheffield
i'm sure i saw it mentioned on BB about using acetone to thin it down. what the affect on setting is i don't know. I am a bit interested in the visocsity of it myself as i have a box of blades from Brisa that i need to put handles on!!

hope that might help

steve
 

jojo

Need to contact Admin...
Aug 16, 2006
2,630
4
England's most easterly point
It is possible to thin epoxy, both by using heat and also by using solvent. The solvent reduces the quality of the adhesion rather drastically.

See more about this on this site: http://www.seqair.com/skunkworks/Glues/WestSystem/Thinning/Thinning.html

I have thinned down the two part araldite inadvertently with heat :rolleyes: , it did not do it any good :(

If you use West Epoxy, the stuff when warmed up harden much more quickly if you have a deep pot, but if you spread it in a flat surface, such as a baking tray perhaps, it takes longer to harden, it will soak readily into cloth, i could show you some of my clothes hardened with epoxy, but I had to chuck them!!!
 

C_Claycomb

Moderator staff
Mod
Oct 6, 2003
7,391
2,407
Bedfordshire
I have used acetone to clean excess epoxy that has squeezed out of a join, only to have the join de-laminate later due to the acetone going where I didn't want it. As has been said, mixing acetone into the adhesive would not be a good idea.

There are a lot of different viscosity epoxies out there, some are casting resins rather than adhesives and can be very runny with a setting time of about 24 hours. In the case of that resin, heating to about 60degC greatly speeds setting and doesn't hurt the strength at all.

I would look at the stuff used with fibre glass mat, it is designed to soak in and sets slow.
 

chem_doc

Tenderfoot
Sep 14, 2007
90
0
56
Atlanta, GA
It's going to be a balancing act. Heating epoxy will make it cure/set much faster.

Adding a solvent would probably be the best way to go, but....

The two parts of the epoxy react with each other. I'm guessing here, but it's an educated guess. The one tube of epoxy is a polymer that has a fairly reactive handle built into it. That "handle" can (and eventually will) react with water. Luckily, the polymer doesn't like much water, so the water can't readily get into the polymer to chew up/destroy the handles.

The acetone available "over the counter" isn't super-pure stuff. Firstly, it probably contains a lot of water and probably some rubbing alcohol, both of which can (and will) react with the handles. Fewer handles in the polymer means fewer bonds to the other tube of glop means lower overall strength.

You could go with a better solvent, but it has to be balanced with evaporating fast enough so that it doesn't get trapped in the polymer after it cures. Trapping the solvent in there will also decrease the strength of the epoxy.

I think that getting a solvent that does all of this without ordering from a chemical supply place would be tough. And the chemical supply places would be cost prohibitive.

With all of that said, have you looked into epoxy paints, such as for garage floors? They can come in either one or two-pot styles and are pretty much low viscosity forms of the glue. They may take a while longer to set up/dry/cure, and I'm not sure if the adhesion properties are as high as the glue, but they tend to make very durable coatings. You may want to consider those.

Doc
 

Pignut

Bushcrafter (boy, I've got a lot to say!)
Jun 9, 2005
4,096
12
45
Lincolnshire
It's going to be a balancing act. Heating epoxy will make it cure/set much faster.

Adding a solvent would probably be the best way to go, but....

The two parts of the epoxy react with each other. I'm guessing here, but it's an educated guess. The one tube of epoxy is a polymer that has a fairly reactive handle built into it. That "handle" can (and eventually will) react with water. Luckily, the polymer doesn't like much water, so the water can't readily get into the polymer to chew up/destroy the handles.

The acetone available "over the counter" isn't super-pure stuff. Firstly, it probably contains a lot of water and probably some rubbing alcohol, both of which can (and will) react with the handles. Fewer handles in the polymer means fewer bonds to the other tube of glop means lower overall strength.

You could go with a better solvent, but it has to be balanced with evaporating fast enough so that it doesn't get trapped in the polymer after it cures. Trapping the solvent in there will also decrease the strength of the epoxy.

I think that getting a solvent that does all of this without ordering from a chemical supply place would be tough. And the chemical supply places would be cost prohibitive.

With all of that said, have you looked into epoxy paints, such as for garage floors? They can come in either one or two-pot styles and are pretty much low viscosity forms of the glue. They may take a while longer to set up/dry/cure, and I'm not sure if the adhesion properties are as high as the glue, but they tend to make very durable coatings. You may want to consider those.

Doc


Lab grade acetone?
 

thedude

Member
Mar 2, 2005
17
0
40
Exeter / IOW UK
I would recommend popping to your local boatyard (or kitcar manufacturer :D ) and asking for some polyester resin (boatbuilding epoxy as they said above). It is pretty runny and should give a longer working time than epoxy, so long as you dont use too much catalyst (depending on resin <2&#37; by weight should work fine and take longer to set, ask the people that are using it day to day). Ask for their most expensive resin if you can because it will be purer meaning you get more consistent results and price difference is not too much (about &#163;5 /kilo is the expensive stuff if they are buying it in 45 gallon drums). Oh yeah, make sure you get some catalyst too.

Otherwise, as said above, heat works a treat. If you put 2 ton epoxy (available from RS) on a radiator and heat to about 60C (when in 2 parts, i.e. before you mix it) and then mix you should still get 5-10min working time. It is also quite clear and sets hard.

I like 2 ton, tis good stuff.
 

chem_doc

Tenderfoot
Sep 14, 2007
90
0
56
Atlanta, GA
Lab grade acetone?

I still wouldn't use that. It's difficult to get water-free acetone (trust me, I've done it).

I'd go with something like heptane or toluene, but the boiling point of toluene may be a bit high (it's slightly higher than water's). In an ideal world, I'd probably go with something like anhydrous THF or toluene. But I'd try it out first to see how it worked before using it "for real" on whatever it is you want to use it on.
 

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