Microbubbles or whatever you call them

[Allan Dozier]

I would like anyone's ideas on this problem. I am spraying cabinets with SW Kem Aqua Plus which I have done many times in the past with good results. This time I am getting many tiny bubbles, some pop and leave a tiny crater so they are definitely bubbles not detritus. It happened yesterday with the Kem Aqua surfacer which I solved today with a very light sanding with worn 220. I initially blamed the product because I had just ran to the Monroe SW to buy some as I was out of stock. They had put the can in the shaker before I got there so I thought that might be the problem. However, I just applied the topcoat (low gloss white) and it it doing the same thing just not quite as bad. I have had that can for a while and it was only stirred. Here are the other details:


Done in my spray/finishing room with powerful exhaust. The air comes through my refrigerated dryer.
Devilbiss Finishline FLG4. I think it was a 1.3 tip
My on gun regulator bit the dust so I went this morning and got a new one. Running between 19 and 20 psi at the gun.
I dialed the volume back so as to get a thinner film. It helped some but still some bubbles.
If this were a solvent finish I would guess it is drying too fast. The conditions yesterday though was that it was raining at the time I was painting so the fan was drawing in very humid air (remnants of the hurricane). Today the sun is shining with blue skies and still had a problem.


I read that SW recommends using Butyl Cellosolve as a retarder, thinner if this happens but I would like to avoid that if possible. I also read it is not the safest chemical. However, I do use a supplied air respirator. Thanks.

[John TenEyck]

Sounds like it is drying too fast to me, whether or not it was raining yesterday. I never could spray Kem Aqua Plus to a satisfactory finish (same problem, rough, micro bubbles, etc) until I added a few percent of GF's Extender to it, around 3% I think. After I did that it was one of the nicer finishes to spray. Not as nice as GF's Enduro Clear Poly though, or TC's EM-6000, or Lenmar's Duralaq WB. Those spray dead smooth with no problems for me.

Spraying a thinner coat isn't a good approach if the problem is caused by drying too fast. A wetter coat with some Extender added will have longer to flow out before it sets, leaving a smoother surface with fewer/no bubbles.

GF's Extender is propylene glycol in water, about 33% IIRC.

Hope that helps.

John

[Allan Dozier]

Thanks for the input John. I probably need to just switch over to Target. It was just so timely to go pick up the can of primer. I didn't realize they shook it until I heard the manager tell her assistant the it was in the shaker. The top coat came out quite a bit better than the primer.

I just made another observation though. The face frames and the drawer faces are solid soft maple and they basically did not have any bubbles. The 3/4 maple plywood I used for this set of cabinets I got from a hardwood dealer and it weighs much less than I am used to. A 4x8 weighs 42 lbs. and I think what we usually use weighed around 70 lbs. The veneer looks fine but the inner cores are very porous and light. I wonder if it is air coming out even through the layers of primer.

[John TenEyck]

Well that's an interesting observation. Never seen plywood that light. I don't know why air should be coming out of the pores, but nearly anything is possible. Is the bottom side sealed or not?

John

[Allan Dozier]

Yes, both the inside and outside of the cabinets are painted. But you are correct that there is no reason for air to come out that I can think of. The temperature didn't vary much. When it started to rain it may have even dropped slightly. I am too cheap to not use the rest of the KA+ but I think I will see about adding a retarder next time. I have access to plenty of propylene glycol. So it will evaporate just like water or alcohol?

[John TenEyck]

I doubt propylene glycol evaporates like water or alcohol, but it doesn't interfere with the finish, just allows longer time for the wet coat to flow out.

John

[Jeff Roltgen]

Very interesting thread. My current product of choice (Mohawk Enduragreen WB Conversion Varnish) has been giving me fits in a similar fashion, but only just recently. My approach to the issue reads pretty much like Allen's. Based on John's responses, decided I'd see if they offered an extender, and sure enough, they have it. Even more curious under the same heading for water-born additives:
"Bubble Breaker" additive. ($89 a pint!)

Extender makes sense, but bubble breaker is more to the point, regardless of cost. With all the vertical surfaces I'm typically faced with, I really want to avoid risking runs/sags by thinning (already maxed out at 5%) and extending dry time. Wonder what's in it to push the cost so high and delineate it from simply an extender?
The chemistry of these advanced finishes seems to be getting quite complex any more.

[Tom M King]

Just started doing a bit of searching on "bubble breaker" and interesting that this says it works in epoxy too.

https://decochem.com/wp-content/uplo...le_breaker.pdf

[Tom M King]

This sounds like it has something to do with trapped CO2, or at least in MCU.

https://blog.chasecorp.com/specialty...floor-coatings

[Tom M King]

I didn't know Constantines was even still in business. Here it is for less cost if you need smaller quantities:


https://www.constantines.com/waterbo...lebreaker.aspx

[John TenEyck]

I didn't know Constantines was even still in business. Here it is for less cost if you need smaller quantities:


https://www.constantines.com/waterbo...lebreaker.aspx

Well that's nice. You are supposed to read the MSDS before use, but if you want the MSDS you have to request it by mail. It used to be different, before the lobbyists won.

John

[Jeff Roltgen]

Tom - thanks for all the research. Wondered how a re-seller was moving same Mohawk product for 1/10th the price, until I noticed it is 1OUNCE at 8.95, not the pint, which puts overall cost at $143.20 / pint, buying an ounce at a time. If 1oz /gallon does the trick, it will average under $6 per gallon by gritting my teeth and picking up the pint at the outset.

PDS indicates under the heading "Chemical Name" that "no hazardous items exist".

Bonus feature if not blended well for several minutes: Fisheyes.
One wonders why it's not simply part of the original factory mix. Maybe Target coatings does just that, hence my fisheye problems, causing me to avoid all of his products? Would I have had more luck with an extended power mixing session just prior to use? Seems unlikely, but then again...
Good grief.
What a complex mess.