• Gallery Images: Title and Description Required

    Please read the new sticky announcement HERE for full details.

  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

White speckles in epoxy

Joined
Jan 14, 2020
Messages
153
Likes
43
Location
Austin, TX
Hi, I have a piece I put epoxy on. Epoxy is high gloss and I hate that so I sanded it down to get a satin finish. However it seems there are a lot of little white speckles on it now. Probably epoxy dust I don't know. Anyone seen this before or know what I should do?
Thanks,
Raif
 

Attachments

  • PXL_20210602_195224555.jpg
    PXL_20210602_195224555.jpg
    453.1 KB · Views: 52
Joined
Feb 28, 2021
Messages
147
Likes
82
Location
Roulette, PA
Website
www.reallyruralwoodworks.com
air bubbles, looks like. did the wood have any moisture to it? (wood that isn't fully dry can release water as the heat of epoxy cure draws it out) was the epoxy mixed and stirred slowly? (whipping it by stirring too fast will introduce air as well) - slowest possible mixing, slowest and gentlest possible pouring into very dry wood should minimize your air bubbles.. among other techniques with epoxy.
 
Joined
Jan 24, 2010
Messages
3,054
Likes
875
Location
Cleveland, Tennessee
Air bubbles. Fold in the two parts and don't stir rapidly which adds air bubbles.
 
Joined
Jul 18, 2018
Messages
339
Likes
232
Location
Baltimore, MD
Epoxy cures by an exothermic reaction. It generates heat. If the substrate gets hot enough, either from the warm epoxy, or from ambient air temp, air in the pores of the wood will be forced out and get suspended in the epoxy. I Haven’t used epoxy to coat a bowl, so I don’t have experience with this, but in boatbuilding it is recommended to coat with epoxy in the afternoons/evenings as the air is cooling to minimize this outgassing. I’d think that sealing well before applying the epoxy would minimize this.
 
Joined
Jul 26, 2016
Messages
1,995
Likes
888
Location
Nebraska
It is a common practice when making epoxy coated tables to use a torch or heat gun to quickly run heat across the surface of the wet epoxy before it starts to set up. The heat will cause any suspended air bubbles in the epoxy to heat up expand and rise to the surface and pop.
 
Joined
Jul 18, 2018
Messages
339
Likes
232
Location
Baltimore, MD
Also beware that most epoxies (there may be exceptions) are UV sensitive and will yellow and degrade over time if exposed to direct UV light, ( i.e. sunlight), if they are not protected by a UV filtering finish.
 
Joined
May 28, 2010
Messages
4
Likes
2
Location
shakopee, mn
its hard to tell from the picture but you said you sanded the epoxy to knock down some of the shine- it looks to me like sanding dust in some of the torn end grain???? possibly wipe it down with a solvent of some sort?? without softening the epoxy??
 
Joined
Jan 14, 2020
Messages
153
Likes
43
Location
Austin, TX
So I was wondering if I might be able to get the dust out. If not I'm thinking I'll sand it down a bit further and then apply another thin ( if possible ) coat of epoxy.
As per bubbles. I am heating the stuff in the microwave, and it always seems to have ton of tiny bubbles. I have like a plumbers torch, for sweating copper. Would that work? Perhaps it's the brand. I'm using System 3. What brand of epoxy do people like?
Thanks,
R
 
Joined
Feb 28, 2021
Messages
147
Likes
82
Location
Roulette, PA
Website
www.reallyruralwoodworks.com
rather than heating the epoxy you might consider learning how to do epoxy in a pressure pot. Pressure pot compresses any air in the resin eliminating the bubbles. You need to read up on your epoxy of choice and see if it is intended for Casting (which generally would need a pressure pot) or a deep pour (river tables and the like) or bartop (thick shiny surfacing) Go to the manufacturer's website and read carefully ALL of their instruction sheets on how to use each specific model/formulation that you are using.. The devil is in the details - Some require mixing by weight (which means *exact to the gram* weights - "close" ain't good enough) , others by volume - again exact measure would likely be important.. If you mixed an epoxy that needs precise measurements (weight or volume) and get one proportion wrong, you can end up with "pockets" - same if it is not completely and thoroughly mixed - you can get little pockets of unmixed part A resin that didn't get mixed with hardener which never cures, and when you turn it down you get little spatters of uncured stuff thrown at you.

I'd probably try and flush all the dust if any out with a bit of compressed air in a can (shop air can blow moisture and small particulate, invisible droplets of oil, etc) and wipe the surface down with a fast evaporating solvent compatible with the epoxy you are using, then mix another small batch very carefully and spread it on thinly with a clean putty knife or plastic scraper and let that cure, then sand again, in the hopes that the thin surface coating would fill all the tiny voids left from the air bubbles.. with any luck it might all bond together and your dust pockets disappear.. worst case, the dust pockets get sealed in, in which case you can always turn away a bit more and try sanding again until you get the finish you are after.
 
Joined
Jan 14, 2020
Messages
153
Likes
43
Location
Austin, TX
Thanks for your detailed reply Brian. I don't know much/anything about pressure pots except that when I've seen them they look to be like 3/4 gallon. When I use epoxy I use it on vases ( at least the inside to water proof it ) and flower pots ( same ). I feel like those would not fit. Further, I need to keep the thing spinning in order to keep it from pooling up. So I'm thinking that may not work.
I am using system 3 epoxy ( but I'm looking for a new brand if anyone has any suggestions, if only to avoid having to do the math ) which is 100/44 and I use a cooking scale. I get it pretty close.
Thanks,
R
 
Joined
Dec 22, 2006
Messages
5,658
Likes
2,452
Location
Panning for Montana gold, with Betsy, the mule!
I am using system 3 epoxy ( but I'm looking for a new brand if anyone has any suggestions,

I've been using Devcon 2-ton clear epoxy for quite a long time now.....with satisfactory results. I prefer the slow set version, over the 5-minute formula. I don't recall ever being plagued with bubbles. Since I'm using an artist's palette knife to mix, and it's not aggressive.....that probably helps. My purpose is to fill small cracks and voids, so I'm not mixing large quantities at a time.

Don't know if the Devcon epoxy would be a better solution for you, but it wouldn't be too expensive to give it a try! ;)

-----odie-----
 
Joined
Jan 14, 2020
Messages
153
Likes
43
Location
Austin, TX
Hello. So sanding down a bit definitely removed some and then a new coat took care of the rest.
I sanded it down a bit to make it more satin.
And I did other horrible things. I'm going to update some of the million other posts that I made on this project. Plus post another on repair.
One note on mixing and bubbling. One thing I heard was that mixing with a wooden stir introduces bubbles. I certainly don't mix vigorously but I do use a popsicle stick to stir and I have millions of little bubbles when done. I let it sit for a bit and many go away.
Thanks for the help.
R
 

Attachments

  • PXL_20210602_195224555.jpg
    PXL_20210602_195224555.jpg
    453.1 KB · Views: 8
  • PXL_20210606_190455328.jpg
    PXL_20210606_190455328.jpg
    401.1 KB · Views: 8
  • PXL_20210606_193829700.jpg
    PXL_20210606_193829700.jpg
    451.4 KB · Views: 8
Top