Bubbles in 1st (primer coat)

[rhs]

Hi all.

I'm using a 100% solids epoxy and was advised that I should apply 3 coats: The first works as a primer, add flakes to the 2nd coat and then anti-slip grit to the 3rd (clear).

The floor was diamond ground, patched and well cleaned. Prep went well but after spreading the 1st coat I have some questions:

1) I tried to be even when rolling out the 1st coat but after drying for 12 hrs, it looks uneven and patchy. It looks as though some of the primer was absorbed by the concrete.

2) I have some bubbles in the 1st coat which probably isn't unexpected given it was a 100% solids product. Backrolling helped, but there are still a few. I assume that if I sand these flush, they will disappear in the 2nd coat.

3) I managed to pickup some grit on the roller (right at the end by the door) which I probably need to pick out and sand flush.

Thanks all!

 

[dcs Inc]

Did you acid etch and power wash? How much time did you give it after water hit the floor. 100% solids epoxy doesn't make for bubbles. After sanding the bubbles, (you should degloss the whole floor) the second coat should fill and hide the bubbles. Try not to apply any more water to it.

 

[rhs]

Thanks. No acid washing and no pressure washing. Just used a hose and a stiff brush to remove all the ground away material. Used compressed air, a brush and an industrial vacuum after that. I ground the floor wet 6 days ago and it has been sitting since. I taped down plastic 48 hrs test spots prior to application just to confirm there wasn't any moisture in the floor and the plastic came up dry.

Will the 2nd coat look more uniform? I'm throwing flakes down as well.

 

[dcs Inc]

Temps rising will draw moisture out of concrete. High humidity levels will create a fish eye. Sometimes these look like a bubble crater. If you can have the temps decending, apply at a humidity less than 80% (50-60 is great) Have your epoxy sitting in the room for at least 24 hours to gain room temp. Don't mix a frothy milk shake when mixing, you should be good to go. Degloss the whole area with sand paper. Sand the ring around the bubble flat and they will dissappear on your next application. Don't worry so much about the indentation of the bubble after you sand down the ring, that should fill. If this is one of these kits sold on here I'm sure it's just a partial flake and not a full broadcast. Pay attention to the amount of flakes per area so you can place them evenly. Good luck. It should go well.

 

[pnut]

Did not see a question but bubbles are not unheard of even when properly prepared.

Good it's in the primer like mine was.

It will ALL show through. Sand or scrape down the defects before color coat. You will be damn happy you did. I wish I had.

Same before clear. Remove any defects.

Good luck.

 

[Edger]

We used to get bubbles after diamond grinding on some jobs, pain in the a$$, they often come through the second coat too. If your floor looks patchy after the primer then you have done a good job. It is supposed to soak into the surface which it seals off as it cures. We resorted to filling the tiny hole that caused each bubble, slow work. Double priming is supposed to stop it, but it did not always work.

 

[rhs]

Thanks everyone. I've decided to do another 'primer' coat of epoxy without flaking and then pickup a 3rd coat with more flakes on Monday. I don't currently have enough flakes for a heavy broadcast (I have 1 lb for 220 sq ft which would be pretty light coverage according to some other posts). Given what it looks like right now, I think more flakes will hide the concrete imperfections better.

 

[Familyof8kids]

Thanks everyone. I've decided to do another 'primer' coat of epoxy without flaking and then pickup a 3rd coat with more flakes on Monday. I don't currently have enough flakes for a full broadcast (I have 1 lb for 220 sq ft which would be pretty light coverage according to some other posts). Given what it looks like right now, I think more flakes will hide the concrete imperfections better.

•Light density requires 1/4 lb. per 100 sq ft.
•Medium density requires 3/4-1 lb. per 100 sq ft.
•Heavy density requires 2-3 lbs. per 100 sq ft.
•FULL COVERAGE requires 15 lbs. per 100 sq ft.

If you have 1lb per 220 sq.ft. then you will have between a light and medium flake content and that WILL NOT help cover existing issues that much. Suggest you use the chart above and lean more toward Heavy coverage if you want to hide issues. Easier to purchase more flake than go I wished I would have got more flake after the fact.

 

[rhs]

I sanded the whole floor today and have put a 2nd coat on the worst areas as an experiment to see how it looks.

I think my expectations of what 100% solids epoxy would do were a little too high given the condition of the floor after grinding. The epoxy isn't leveling to fill what I originally considered to be minor divots and grinding marks as well as I had hoped. I assumed that a 3/8" roller would leave plenty of material for the epoxy to level, but it seems that unless I brush/squeegee it on (and leave it very thick), it is pulling out the divots as I roll.

I will defeinitely be picking up a few lbs of flakes on Monday.

I am starting to wonder if a thick bed of leveling mortar and tiles wouldn't have been quicker, easier and ultimately cheaper...

 

[rhs]

We used to get bubbles after diamond grinding on some jobs, pain in the a$$, they often come through the second coat too. If your floor looks patchy after the primer then you have done a good job. It is supposed to soak into the surface which it seals off as it cures. We resorted to filling the tiny hole that caused each bubble, slow work. Double priming is supposed to stop it, but it did not always work.

I did a test with a small batch for a 2nd coat and sure enough, some of the areas where the concrete has a small pit have again bubbled, fish-eyed or simply been left void of epoxy. I will be filling/patching each hole in the primer before I continue with the next coat.

Many thanks for the tips everyone.

 

[Familyof8kids]

Did it recently rain in your area?

 

[rhs]

Nope no rain, and the humidity hasn't been high for the past 2 weeks.

I spent the morning on my hands and knees filling grinding marks, bubbles and every other divot imperfection I could find with an epoxy crack filler. Not much fun but it should fix my issues with the floor after a little sanding.

After a little thought on the weekend, I worked out that my 1st coat and my test 2nd coat were probably only about 4 mil thick. This may explain why I was seeing so many imperfections. Picked up a batch to go down at 10 mil and more flakes.

 

[dcs Inc]

Degloss it first. (sand it) If after the 24 hour window.

 

[rhs]

Degloss it first. (sand it) If after the 24 hour window.

Thanks. I did give it a good sanding before filling the divots and will do so again before the next coat.