Finish with Air Bubbles?

[conwaygolfer]

I often use poly for the final finish on most thresholds that I make. Most times I end up with small air bubbles (I assume) in the finish. I also assume it is because I brush too much.

My grandaughter wanted a trophy case (3ft x 5ft.) for her birthday. This time I decided to get the perfect finish. I went to Sherwinn Williams and asked for the best natural bristle brush they had. I told him what I was doing and he agreed that I needed the correct brush.
I used 3/4 maple ply thru out. I stained with Cabots Red Chestnut. After a few days I applied a sanding sealer. I sanded with 320 grit and wiped clean. Afterwards I used the brush to apply Deft Clear Wood Finish (Gloss Brushing Lacquer). I thought I followed all the directions on the first coat. I can once again see what appears to be small air bubbles. While the finish is still wet, I slowly and softly brushed over and some air bubbles seemed to disappear. I am not sure about brushing on a second coat until I can remedy the problem with the air bubbles.
If anyone has any answers I sure would appreciate it.
Thanks in advance for your help.
Glenn - Conwaygolfer

[Tom Slick]

Are you shaking the can to mix? do you stir it vigorously? you might be putting air bubbles in before you start brushing.

side note: try the deft spray lacquer in a spray can, it works very good.

[conwaygolfer]

Air Bubbles

Hi Tom,
I only stirred as per the instructions. I have a can of the spray on Deft, but the rear of this project is 3 ft. x 5 ft. and I did not want to spray that much.

After stirring, I can see to the bottom of the can and it is perfectly clear. When I finish with the brush, I usually wipe somewhat clean on the inside of the can and at that point I can then see the air bubbles. But they are gone before I use it again several days later.
Thanks,
Glenn

[Daryl]

You could try thinning the poly, the air bubbles won't be trapped as much in thinner coating. You can also give wiping poly a try, I get a nice deep shine and it dries pretty quick.

[conwaygolfer]

Air Bubbles

You could try thinning the poly, the air bubbles won't be trapped as much in thinner coating. You can also give wiping poly a try, I get a nice deep shine and it dries pretty quick.

I will try that the next time I brush on poly. I recently bought some wipe on poly after reading about it here. Haven't had a chance to use it yet though. Thanks

[SARGE..g-47]

Hand scuff out what bubbles you already have with 320. The first coat is only to fill the pores anyway. Thin your poly at least 20% if you are going to brush it on. If you decide to pad it with a folded cloth cut it 30%-40%. It will give an even flow but you will have to add more coats to build. I never brush anymore.

As stated.. stir gently and allow any bubbles in your can to dissolve. And if you brush... don't overbrush. Tip off the application which means hold the brush almost vertical and lightly (very lightly) drag it across the surface to remove any bubbles.

Again.. I quit brushing years ago and pad with a 70-30 mineral spirits cut. Scuff sand.. use a 70-30 cut again.. lightly scuff sand.. then about 2-3 coats with a 60-40 cut to finish the surface. I never got a great finish with a brush.. but I do padding...

Good luck...

[catta12]

I was also getting bubbles with a Minwax Poly when either sprayed or brushed on. I started cutting it about 40-50% with thinner and the problem was solved. My guess is that your poly is also setting up before the air can raise out. From the research that I did previously it was suggested that the air bubbles also come out of the wood grain on the first coat, hence it is important to have the finish thin enough that it can escape. True or not, thinning helped me anyway.

[sparkeyjames]

You could try thinning the poly, the air bubbles won't be trapped as much in thinner coating. You can also give wiping poly a try, I get a nice deep shine and it dries pretty quick.

What Daryl said. Every time I have tried off the shelf poly straight from the can I get some air bubbles that just won't go away. You really have to thin it down. I use a very fine foam roller or brush to apply it (go slow). Bubbles are gone in a couple of minutes. Thinning it down does increase the dry time slightly though so be prepared to give it an extra hour or two before steel wooling it for the next coat.

Jim

[SARGE..g-47]

The small can of somewhat expensive "wiping poly" is nothing more than standard poly cut to usually 50-50 with mineral spirits. It would save money to make your own.

[conwaygolfer]

Air Bubbles

I will take all this good advise and put it to use. Thanks to each of you who responded. It all makes sense and should give me the final finish look I am trying to achieve. Thanks again,

Glenn - Conwaygolfer

[poolhound]

I always put on a thin sealing coat first an as others have said rarely brush on finishes anymore.

There are also some great Poly/Oil/BLO mixes out there that are really great. Wipes on easily and gives a beautiful finish. You can aslo make your own.