Tips on eliminating air bubbles, specifically tung oil?

[Michael Yadfar]

I used Waterlox Tung Oil for the first time ever on my most recent project, and haven't had all that much finish experience to begin with. I ended up having two issues which were puddling and air bubbles. The puddling I determined was due to not giving enough drying time, but I couldn't figure out how to eliminate bubbles. I tried lightening my brush strokes, brushing more, brushing less, and letting it sit for 15 minutes then brushing. The only two things I haven't tried were using a natural bristle brush (I use foam) and thinning. I was kind of iffy about thinning because Waterlox tells you not to thin.

[Scott Holmes]

Specifically which Waterlox product are you using?

Foam brushes are the leading cause for bubbles. A quality varnish brush (2' about $45-$50) will do wonders to flow the finish without bubbles. Also the error most people made when using a natural bristle brush is using it dry. Watch the Sticky note video at the top of this forum to see what I'm talking about.

Some varnishes need to be thinned before brushing. When the manufacturer says don't thin it's really about VOC rating; not that the product can't be thinned.

[Michael Yadfar]

Specifically which Waterlox product are you using?



Im using Waterlox Original Medium Sheen

[Jim Becker]

These products are varnish, not "oil", which is why bubbles are an issue at all. Bubbles in an oil will just disappear as you rub the product into the wood. Varnish, on the other hand, has to allow any bubbles to move to the surface and then escape into the air. The more viscous the product, the harder that is to insure.

Scott is correct that the type of applicator is very important. Additionally, never "shake" a can of varnish to mix it up. Just carefully stir it to insure the flatting agents are fully mixed throughout the product and then apply with a quality brush or rag. Bubbles shouldn't be a problem then. If you are still getting them, it's likely a combination of technique or the product being too thick to properly apply.

[Prashun Patel]

Im using Waterlox Original Medium Sheen

Do you mean waterlox original sealer finish?

[Michael Yadfar]

Yes, I'm using Waterlox original sealer/finish. The instructions say no stirring or shaking required, so I do neither. With all the dry brushing I tried, I don't think it's too thick either. Unfortunately with the current project I have to give up on it to start on another project, but it's a personal project so I'll probably just sand it down and refinish it another time. The finish actually looks great, but when you look at it on an angle you see all the bubbles, it's going to bug me especially lol. But for my next project I'm going to try some new things, probably natural bristle brush and maybe thinning, because I actually really love the look of the finish. It's pretty heavy duty, and really pops out the wood very well, and adds a nice slightly darker color, it's my favorite so far (I've used Danish Oil and Polyurethane in the past).

[Prashun Patel]

Just use a better brush

[Sam Murdoch]

When I apply Waterlox by brush on a big top such as a bar top I generally (after being very certain to meticulously clean the surface, surrounding area and myself of dust and other potential debris) apply a pretty liberal coat with a good natural bristle brush to coat the entire surface. The finishing touch however is to tip off from one end of the other in long even and light passes using a 4" foam brush. The brush is pre-moistened with mineral spirits just to be soft BUT not soaked in MS - just dampened. I squeeze it with paper towels before use. These long light passes even out the brush strokes and - in my experience - leave a near glass surface with no bubbles. I also find that it is best not to have the room over heated. 62° to 65° with no (or minimal) draft is plenty. Too hot, 70° or more, just seems to create issues with leveling out of the Waterlox.

I think you might be creating a problem letting it sit for 15 minutes. I apply with bristle brush and tip off with the foam brush all in one uninterrupted process - no waiting.

[Brian Thompson]

Waterlox Original has no added flattening agents, like you would encounter with a satin poly, so there is no reason to shake it.

If you are getting air bubbles, all you would need to do is lightly sand (wet or dry) that coat to get rid of the bubbles (or dust nibs), and then wipe-on a light final coat or two with a lint-free rag. Also, make sure there isn't any dust being stirred up while the finish is drying. Otherwise, no matter what application method you are using, there will be imperfections in the finish.

Edit: Make sure you thoroughly clean the surface after the sanding.