West Systems 2-part Epoxy Resin - Removing Bubbles

Hi All,

With the help of a friend, I recently completed making a computer desk from a Marri slab, and as anyone who has worked with Marri will know that there was a fair bit of filling to do for the massive voids and sap lines.

We used West Systems 2-part epoxy resin which gave excellent results, but found that small air bubbles were a problem a lot of the time.We did our best with a pin, but I've since read on this forum that people have some other tips for removing bubbles, such as:

- Stir resin and the hardener together slowly with a wide stirrer;
- Use a heat gun to heat the voids in the wood before pouring the epoxy in. This apparently makes the bubbles rise to the surface because the wood is warm;
- Use a heat gun (low pressure) on the resin once it's poured in.
- Then pop remaining bubbles with a pin.

I heard from the guy that I got to do the initial levelling and sanding of the slabs that you can hook up a hose to your car exhaust and blow the exhaust onto the affected area of resin shortly after pouring and this dissipates any bubbles...something to do with the Carbon Monoxide in the exhaust?

I never actaully tried it, but interested to know, does anyone have experience with this, and does it work?

Cheers,

Chris

(this is my first post - I really enjoy the forum and the feedback everyone gives)

A big breath from your mouth will usually work. Sometimes I use 25mm retic pipe and breath down it.

Hi Wongdai,

I forgot to mention in the thread above, we did try this with small straws, but found it wasn't that effective. It was also a tough slog seeing as we used so much resin over such a large slab. Another problem with this was that condensation formed in the straw after a while and occasionally dripped into the wet resin, resulting in a cloudy spot.

Hey Chris,

My experience with filling voids with epoxy, you shouldn't use layers of more than about 6-7mm, sometimes you may need to do 3 or 4 layers to get them level. Also pouring from a height of 250 - 300 mm leaves a stream of about 1 - 1.5 diameter, this breaks up the bubbles before they get to the void, you cannot rush epoxy, if you build up too quick, you get clouds because the resin hasn't had time to disipate the heat and the vapours from curing, you won't see any layers from above the fill, only if you can see from the sides.
The idea of blowing on the job is to use the carbon dioxide to disipate the bubbles, a propane torch is best, but don't get too carried away,(or blown away) waving the flame about 200mm above the job will work wonders. The rule of thumb that I was taught was if it was warm enough to work in a Singlet and shorts, about 25 degrees C (Minimum) don't bother mixing the brew. I usually leave the gear out in the sun before mixing the brew so that everything is warm, and haven't had a problem since.

Just my 2 bobs worth.

Just noticed you are in Perth, Have a chat with Charlie or Lainee at Fibreglass and Resin Sales, they will set you straight. (No affiliation just a satisfied customer)

HazzaB

Hazza,
Thanks for the tips, I'll keep them in mind for the next time, and thanks also for the contact.
Cheers, Chris

The best way to remove bubbles from epoxy once you've mixed it is to put the mixture under vacuum. This may be difficult without a pressure pot of some sort and a pump but certainly works. I guess try other peoples methods first as they would be much cheaper.

Ash

hi do you think that vibration will work to dissipate the bubbles. so using like a concrete vibrator to vibrate the resin??

I don't think carbon monoxide (from car exhaust), or carbon dioxide (from breath) is the active ingredient.

Low-pressure wind, e.g. from breath (if you can maintain long enough), or a hair dryer at its lowest heat setting, creates a slight vacuum above the epoxy or varnish, so that the bubbles pop from internal pressure. The same principle (called Bernoulli effect) lifts airplane wings. Also used in venturi to create vacuum in carburetors and other applications. Leaf blowers can create a similar phenomenon.

Cheers,
Joe