How to remove air bubbles from clear resin

I'm using a 2 part clear resin to fill largish holes and often get air bubbles. How do I get rid of them. I've tried poking them with a fine needle but I'll be there for years. What are the easier techniques.

Regards
Greg

Try breathing or holding a flame over the resin. Do not touch the resin with the flame though. Or blow trough a straw over the resin. The carbon dioxide in the breath or around the flame gets the bubbles out. I don't know the mechanism but it works well with Envirotex and the like.

As Joe says, heat brings he bubbles to the surface. I use a hot air gun - less fear of fire.

AlexS


The problem I have with a heat gun or hairdryer is that it can introduce a lot of dust to the surface and the only way to rid the surface of dust particles is to burn them. For that reason I prefer using a flame above the surface. I have done that lots of times and never had a fire.

I find that the best way to avoid bubbles is in the mixing, try not to stir the mix but use a paddle pop and fold it together slowly.

I spent a little time repairing multilayered printed circuit boards for aircraft and as you can imagine there could be no bubbles at all. real pain in the a@#$,

cheers

Dean

I build a lot of fishing rods using 2 part and always use a heat gun to clear the bubbles. Never have any worries with dust, beautiful crystal clear finishes. I suggest that my heat gun (like a paint stripper type) has an element that glows red hot in use and this probably burns the fine dust particles.

I have also used it with stuff...eerrr 2 pack polyurethane with good results. You have to be careful not to overheat. I started out with great results and got carried away removing bubbles and burnt the epoxy:( .

Cheers

This is getting a bit scarey....you know the bit that glows red in a heat gun or hair dryer...that's an ingnition source!

And you know the stuff you can smell in the air when you are using two-pack? That's solvent.

Even if you guys have been lucky, and the stuff you are using isn't particularly flammable...someone reading this post may try with an acetone based product or similar...and die!!

Sorry, in my youth I lost two mates in surfboard manufacturing fires. Both glassing in garages heated by electric filament heaters.

Use heat by all means...BEFORE you open the paint/2pack. If you heat the surface of the material, the entrapped air bubbles will expand, use a cool(er) product and they will contract and not come through the surface.

(These are not bubbles in the brew you are applying, these are the ones that bubble up from below the surface of the timber!)

Cheers,

P :cool:

BM Sorry to hear of a terrible experience. Appreciate your situation Midge and good words of caution. Almost all these products carry various warnings. Even Neils book contains some warnings about warming your brews.

I must point out that using some warm air is much safer than a flame. A heat gun is blowing toward the product not sucking from it. I learnt the technique from a guy at Pt Douglas who had doing it for over 15 years. Turns out its very common practice with the pros (at least in rod building) and many varnish finishes on electrical/electronic components. I used to spend hours trying to carefully mix my resin and not gets bubbles in it etc. but I can guarantee you that very few bubbles will come out from a (sanding) sealed timber into the mix during normal application. The bubbles come in the mixing and application, particularly by brush. Poly is quite suseptible. You only need a waft of warm air before its gone off too much and bingo there gone.

I guess if you pump a lot of heat into the timber you will liberate lots of bubbles. Thats what I meant about getting carried away. Again you are wise to recommend caution.

Greg's question came from the use over "largish" holes and this is probably due to the entrapped air in crevices/defects so I guess the best way would be to fill the holes before finishing.

I just checked out a can of Cabothane and it warns to keep the product away from "ignition sources" and not to smoke while applying.

Anyway, as always err on the side of safety. Use of such a technique without knowing what your getting into could be lethal. Follow the manufacturer's instructions and contact them for advice on a non-standard technique.

I have had far less trouble with poly by a) thinning for first two coats and b) not applying in cold weather.

P.S. Home testing of finishing product flash points may void your household insurance policy.:D

Some warnings about smoking when using chemicals are more about the fumes that often become more toxic and sometimes lethal when inhaled through a lighted cigaret. The flammability aspect is also important but the inhaled fumes are often much more life threatening than the threat of fire. :eek:

Cheers - Neil :)

PS In short don't smoke when using any chemicals. :mad:

This seems to be the thread I need. Wish I'd read it Friday instead of today.:o Another lesson I won't forget re using epoxy.

I've put the first coat of West expoxy on to the camphor laurel eatery benchtop and besides insect trails and the insects themselves, it's come up with heaps of bubbles. (and the beautiful grain showing thru).

The question is where do I go forward from here:
Option 1:
sand back (wearing a respirator)
recoat with a roller
pop bubbles when they appear

Option 2:
sand back (wearing a respirator)
heat gently with hairdryer
and then recoat with a roller?

Thanks
RufflyRustic

Im wondering if we vibrated the mixed resin before pouring it would it disapate the air bubbles?

Quote:

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Originally Posted by rufflyrustic

I've put the first coat of West expoxy on to the camphor laurel eatery benchtop and besides insect trails and the insects themselves, it's come up with heaps of bubbles. (and the beautiful grain showing thru).

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Wendy,
See my post above! The little bubbles in the epoxy coating are doubtless "outgassing" caused as the epoxy displaces air in the pores of the timber.

Since you already have a coat on, sand back, and recoat with a foam roller, cut a piece of foam roller (or use a foam brush) to brush out the finish.

Don't despair, you'll need a third coat anyway, before you get out the polyu!

Cheers,

P :D

:) Have been down this road with Envirotex a couple of years ago, instructions said to use butane torch or similar, or exhaling through a straw, which will produce CO2.
I thought it must require heat to pop the air bubbles trapped and NO, it DID NOT work! I then spent several hours sanding away to get it back to where I started, purchased butane torch & tried again. This time with perfect results!
It is the CO2 which does the trick. Bar top still looks fantastic.
Good luck, regards Sandman

Thanks Guys
I have plenty of straws. Banging the mix to get some bubbles out is easy, if don't gently so it doesn't splash around.

A third coat???? Groan, guess the bench won't be finished by next Wednesday for when the inlaws arrive :(

So no need to warm the bench with a hairdrier first? - After reading the thread again - no, no need to warm it, just do what Midge said :)

thanks
Wendy

On a small area a straw will be a reasonable thing, but on a bar top its a lot of huff & puff.
Also be carefull of breathing the fumes, you might end up with a screaming headache if you are breathing heavily and breathing in the fumes.
Im sure that bloke of your will have a gas torch in that big shed of his. :D

One other point is to be carefull how you mix. use a folding action & try not to entrap air whilst mixing.

Because this stuff is slooooooooow to go off it is wise to have some form of dustproof shelter ready to cover it as soon as you are happy with the bubble situation.

perhaps you could wait for the inlaws to arrive & give them all a straw :D
cheers

Just as Midge says - outgassing and once you get more coats on with a sand in between and it will be great. I had exactly the same problem when coating a boat with West System (and other epoxies too).Looked like a non-skid hull! West reccommend that you coat as the temperature during the day starts to drop rather than rise to minimise the outgassing. I have also had an inapropriate outgassing:o after coating a deck with a decking oil no doubt for similar reasons and with a similar solution.
cheers
Salty

I was doing some reading on applying epoxy for glassing boats. a few suggested to epoxy when the temperature is dropping. their reason was that as the timber heats up it releases air (as bubbles in epoxy), but when it cools it absorbs air (drawing the epoxy into the timbers cells. Don't know how true this is cause I havent tried it, anyone else heard of this?

beat me to it Salty, must be that internet echo Al was talking about :D

Inlaws - hot air, huff and puff....... Yes, plenty of that coming :(

Hmm, the first batch of test epoxy I applied just after mid-afternoon - very few bubbles -this was on the back and underside of the bench, just over the splits, cracks, holes - end result very few bubbles. The next day I applied it to the top of the bench - in the middle of the day :rolleyes: live and learn....
I'm hoping to get another coat on after 4:30 pm during the week as the weekend will be taken up with 2 bbqs, one being Midge's, so that should sort out the cooling temperature bit.

Yep, I'm gonna have to get a dust covering on it somehow, maybe do this in hwmbo's shed instead outdoors. I wonder if I can get away with it.....:D

Thanks
RR

Quote:

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Originally Posted by Slavo

reason was that as the timber heats up it releases air (as bubbles in epoxy), but when it cools it absorbs air (drawing the epoxy into the timbers cells. Don't know how true this is cause I havent tried it, anyone else heard of this?

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Very true.

No need to ask me how I know!!

cheers,

P
;)

This stuff may be mentioned elsewhere but.
Temperature and humidity seriously effect how this stuff performs. The stuff I used had a recomended temp & hum window fro best results. Even the small amount I have done this was aparnt. one bloke I know who used to mount posters with this stuff regularly had a "climate controlled room" (aircon & a simering sauspan) :D.
It is also recomended by some to seal the surface so the air wont come out. With either "special sealer" or shelac.
cheers

I have read with interest the use of a heat flame above the resin to remove bubbles apparently due to the formation of Co2.I use clear cast polyester resin, will the same technique work. I noticed most of the threads were about epoxy resin. Is there any safety issues using the system on polyester resin.