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Water Thin Epoxy

Lo-E

Lo-E

Dec 19, 2009
8,462
14,396
58
Brooklyn, NY
#1
Calling @Bruce Johnson!
And @MPU!

Bruce has mentioned the use of water thin epoxy on many occasions in this forum and, specifically, has referred to products by both West Systems and Total Boat.

In the case of Total Boat penetrating epoxy, Bruce has mentioned that it does not harden to the extent that West System does.

In discussions about crack repair, Bruce has mentioned using water thin West System epoxy but, in my experience, undiluted West System is more the consistency of thin syrup and would not easily wick into a narrow crack. A white paper published by West System advises that thinning their epoxy (no more than 5% with mineral spirits) has a pronounced negative impact on the strength of the cured epoxy so, in other words, it would be similar to using the Total Boat penetrating epoxy.

So, my question to those of you who use epoxy in repairs is this: how do you achieve good wicking properties in epoxy without sacrificing strength?
I realize that everything in life is a compromise but I’m interested to know what and where you choose to compromise.

Thanks!
 
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#5
MPU said:
You can heat the epoxy to get it thinner. That does not sacrifice the strength, just makes it cure faster and increase the strength. Downside is shorter pot time so you have to plan your workflow so that you have enough time before epoxy gels and starts curing.
You can also heat the work pieces to get deeper wicking.
Click to expand...
That’s a very interesting option. I imagine it would take quite a bit of trial and error…

It’s been quite a few years since I used West System but I remember the pot time being in the range of about 20 minutes. Heating the work seems easier and safer than heating the epoxy itself but it would probably be hard to predict the effect upon the pot time.
 
#6
UntitledProject said:
Depending on where it is to be used, there are uv curing resins made for glass repair that are very thin and meant to quick into tight spaces. These have a long work time (as long as you're out of sunlight) and can be cured on demand.
Click to expand...
I’m not sure how I would apply UV through an opaque material such as wood, though. It might be fine applied to the surface or, as designed, when used for glass.
 
#7
UntitledProject said:
Depending on where it is to be used, there are uv curing resins made for glass repair that are very thin and meant to quick into tight spaces. These have a long work time (as long as you're out of sunlight) and can be cured on demand.
Click to expand...


Does the resin actually cure, or maybe more accurately does the UV penetrate to cause curing if the resin soaks into the wood? I tried the I Can’t Believe It’s Not Lacquer stuff and found end grain needed to be sealed before application otherwise it would soak into the wood and never cure.
 
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#8
Lo-E said:
Calling @Bruce Johnson!
And @MPU!

Bruce has mentioned the use of water thin epoxy on many occasions in this forum and, specifically, has referred to products by both West Systems and Total Boat.

In the case of Total Boat penetrating epoxy, Bruce has mentioned that it does not harden to the extent that West System does.

In discussions about crack repair, Bruce has mentioned using water thin West System epoxy but, in my experience, undiluted West System is more the consistency of thin syrup and would not easily wick into a narrow crack. A white paper published by West System advises that thinning their epoxy (no more than 5% with mineral spirits) has a pronounced negative impact on the strength of the cured epoxy so, in other words, it would be similar to using the Total Boat penetrating epoxy.

So, my question to those of you who use epoxy in repairs is this: how do you achieve good wicking properties in epoxy without sacrificing strength?
I realize that everything in life is a compromise but I’m interested to know what and where you choose to compromise.

Thanks!
Click to expand...

Hello Ethan;

I don't think there's any good answer here. I don't know of any epoxy which can wick in like CA glue and have full strength. You can thin West Systems somewhat, but it still isn't as thin as CA, and it will lose some strength.

The Penetrating Epoxies, like Total Boat and Smith's, will seep in small cracks. They have moderate bond strength, but they always stay a little rubbery. They aren't really made to glue things together with strength. They are made to fill space and seal up porous wood. And they provide a good base; West Systems bonds very well to cured Total Boat Penetrating Epoxy.

For repairs, I use West Systems, un-thinned. When parts are broken off, I apply the epoxy to both sides of the joint and lightly clamp them together. This provides very good structural strength. And, unlike woodworking glues, if there are any gaps in the joint the epoxy will fill the gaps and harden to full strength.

For surface cracks, like on a fingerboard, I also use un-thinned West Systems, pushing it down into the crack as far as it will go. Then let it cure. Usually, it will sink down in a little bit more as it's curing. Add some more on top, if needed, to fill it up to the surface. That's plenty of strength to fill the crack and keep it sealed up.

West Systems will withstand severe changes in temperature and moisture without shrinking or cracking. I've tested this myself.
 
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#10
MPU said:
I’ve seen someone using suction cup to get the epoxy in deep cracks. Wipe the epoxy on the surface, then press and pull suction cup over and over the area you want the epoxy fill. I haven’t tried this myself.
Click to expand...

For filling cracks, I usually use West Systems epoxy with the Slow 206 Hardener. I daub a bead of it on the crack, pushing it down in with the applicator. Walk away and check it again in 15 minutes. It will sink down further into the crack by gravity. Add some more, check again later. And again. After a few times it will have soaked in as far as it can go, and begun to cure.
 
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#15
41Hz To Go said:
I like to use this 48 hr Promise Epoxy. Easy to use, 1:1 mix ratio. Slightly heat the surface to remove bubbles and it will level/ wick as it settles. You can keep adding until the level stops going down.

https://www.amazon.com/dp/B01LYK2NA...KME3DRTGM&ref_=list_c_wl_lv_ov_lig_dp_it&th=1
Click to expand...
I use these Plastic transfer pipettes to place the epoxy into tight spaces. You could also use a toothpick when only a little is required.

https://www.amazon.com/dp/B0BRKK34VM?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
 
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#16
Lo-E said:
I’m not sure how I would apply UV through an opaque material such as wood, though. It might be fine applied to the surface or, as designed, when used for glass.
Click to expand...
Yes, good point. UV-curing epoxies are more designed for layer-by-layer fabrication of composite laminates (such as advanced fiber placement techniques), where the surface that needs to be cured is always openly exposed to the UV light. Thus, it is not ideal for this application
 
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