Thinning Epoxy?

[Frog4]

What to thin epoxy with?

Does anyone know where I can find research with cross-sections cut that show there's proof of the epoxy penetrating plywood?

Some of the literature I've read states that most "thinners" evaporate rapidly, which would defeat the purpose of them actually being able to "penetrate" plywood ...

[gonzo]

Never thin epoxy. If you need less viscosity either heat it or buy a low viscosity formulation. Thinners degrade epoxy

[Jimbo1490]

Use Heloxy 61 or 68. Increase the curing agent fraction to regain stoichiometry.

[Jimbo1490]

Originally Posted by Frog4

What to thin epoxy with?

Does anyone know where I can find research with cross-sections cut that show there's proof of the epoxy penetrating plywood?

Some of the literature I've read states that most "thinners" evaporate rapidly, which would defeat the purpose of them actually being able to "penetrate" plywood ...

Evaporation does not defeat the purpose at all! In fact it's desirable. Epoxy primer is just epoxy resin with some pigments added and diluted with a 'non reactive' diluent. A non-reactive diluent is incapable of meshing chemically with the resin system during cure, so if any remains in the mix after the cure is well under way, the cured state properties will be severely degraded; you'll get mush.

But the diluent need only remain in the mix long enough to get the resin to where you want it, like shot out of a spray gun or saturated into cloth or in your case, brushed onto wood. If you choose a very volatile solvent like MEK for the diluent, then its a virtual certainty that the diluent will have all evaporated by the time the resin cures. So in the end all that will remain is undiluted resin, which is a good thing.

Reactive diluents like butyl glycidyl ether (Heloxy 61) or neopentyl glycol glicidyl ether (Heloxy 68) ARE capable of meshing chemcally to become part of the cured resin mass so the need not evaporate before cure (and they won't).

There's nothing that says you cant use both types in one formulation, either.

Jimbo

[gonzo]

Demand a written warranty from anyone that sells you a thinner for epoxy

[Stumble]

1) never thin epoxy. Other than a few sellers of just thinned epoxy no one else will recommend it for their products.

2) thinned epoxy doesn't penetrate any deeper than unthinned into plywood, or solid wood

[Jimbo1490]

Virtually all commercially available resin systems like WEST use reactive diluents. WEST is made of DGEBPA resin. Yet look at their advertized viscosity: there is no 'pure' BPA resin in existence with viscosity that low; it just does not exist! Search all the data sheets you want but you'll never find a plain BPA resin that thin! They get that low viscosity by adding reactive diluents.

There is a better way, though: Start with a superior BPF resin. They always have lower viscosity for the same molecular weight. But they do cost more.

[PAR]

Jimbo is correct in that monoepoxides like Heloxy 61 or wetting agents, such as Heloxy 68 will reduce viscosity, with the understanding of what it will do to the cured physical properties of the resin. Some of the physical issues will be tensile strength dropping substantially and water absorption rates rising by as much as 50%.

The point being misunderstood here is, do you really want to open this can of worms and more importantly do you have an understanding, of the chemical and physical realities thinning epoxy can bring to your project. If some or literally any of this seems over your head, then use the hot on hot method or select a resin system with a lower normal room temperature viscosity.

The real question here should be why do you want to thin your epoxy? If you think penetration will make a more waterproof surface, you are under a false impression, possably advertising hype derived. Tests have shown that substrate penetration has little bearing on how well a coating waterproofs anything. These same tests concluded that the quality of the coating is what counts, not how deep it penetrates a substrate.

Lastly, anything that does penetrate plywood will get as far as the first glue line then stop, making the whole penetration issue moot, as the core veneers are still dry.

Again, why do you want to thin your epoxy?

[Frog4]

a LOT of info to digest in this thread so far thanks for sharing what experience and knowledge you have on this ...

the "hype" is what I was questioning ... which is why in the OP I requested:

Does anyone know where I can find research with cross-sections cut that show there's proof of the epoxy penetrating plywood?

I wanted to verify all the plywood builder logs I've read where folks swear that's the way to go.

I need EVIDENCE before I put money, time and energy on something. ..

[philSweet]

If you want to gain some penetration you can heat the wood thirty degrees F by any means you like and apply the epoxy. Keep rolling as the wood cools. I have done this on brightwork that is to get a layer of deck cloth, more epoxy and varnish. After ten years of Florida sun, the epoxy is shot no matter how much varnish you've laid on. If you undercoat, you can lift the old glass off without raising the grain of the plywood. I often add powdered stains or dyes to the undercoat, which probably helps with the release as well. Basically, I do it for the exact opposite of the reason usually given.

[Frog4]

at what temp should I stop heating the plywood? We live in Arizona, high heat is the NORM around here ... ambient temps of 120°F + is easily attained ...

[Stumble]

Frog,

Take a look at http://www.westsystem.com/ss/thinnin...-system-epoxy/ west details some of the options in how to thin epoxy, and they have a huge collection of studies, testing, and how too guides. Basically they suggest increasing the substrate temp to around 115F and working with room temp epoxy. This gives you the best combination of working time, and penetrating.

Again though I have never seen any study that indicates deeper penetration has any significant effect on any measurable factor. It doesn't increase bond strength, water proofing, or anything else from what I can find. The only advantage seems to be in vacume infusing, which is an entirely different ball of wax.

[Frosty]

I thinned some epoxy yesterday with acetone and it went foamy and turned into gorila snot. I dont advize it.
I had to scoop it all out and do it again --

[JRD]

My understanding is that the penetration through the face grain is much less than originally suggested by the promoters of the technique, but gets the job done by providing a coating rather than actual grain saturation.

Years ago I used to use Everdure for sealing wood surfaces during refurbishments, at that time not being aware of pure epoxy encapsulation as such.
Considering the amount of obvious evaporation this appeared to be a very light weight surface sealant compared with three coats of epoxy which seems to be the accepted practice. Arguably the sealing properties of the Everdure may not hold up to what can be achieved using epoxy.

I am wondering if there is a typical weight of epoxy per square meter (foot) of Gaboon ply to achieve full waterproofing? Obviously this depends on the application method, but ultimately what is the lightest weight that can be achieved and what is the best application method to do this?

[tunnels]

Originally Posted by Frog4

What to thin epoxy with?

Does anyone know where I can find research with cross-sections cut that show there's proof of the epoxy penetrating plywood?

Some of the literature I've read states that most "thinners" evaporate rapidly, which would defeat the purpose of them actually being able to "penetrate" plywood ...

Never thin epoxy BUT you can use a slow hardener so it has lots time to penetrate . It will only go to the first glue line anyway so a thin veneer wont take long to soak . Thick veneers take longer so use slow hardener . Really quite simple !!