Varnish woe's

[STORMRIDER151]

Hi Folks,
We need a little advice on varnishing the sides of our build. The history, for the last few weeks we have been staining and varnishing the sides of our build. We stained the sides with four coats of stain. Then we started varnishing the sides. We are using Minwax helmsman spar. Each coat is applied using a roller after hand sanding with 400 grit sandpaper followed by a good wipe down with tack cloth. The plan was for 9 coats.
The problem is after 8 coats they look like my first girl friends acne. This happened after just the 8th coat. We have tried sanding it out but no luck so what did we do wrong? And any suggestionn on a fix would be greatly appreciated. I'm thinking start over but really don't want to do that. It might be important to mention that this has been done on the bench, in the garage with door closed.

[Wolfgang92025]

Hi Folks,
We need a little advice on varnishing the sides of our build. The history, for the last few weeks we have been staining and varnishing the sides of our build. We stained the sides with four coats of stain. Then we started varnishing the sides. We are using Minwax helmsman spar. Each coat is applied using a roller after hand sanding with 400 grit sandpaper followed by a good wipe down with tack cloth. The plan was for 9 coats.
The problem is after 8 coats they look like my first girl friends acne. This happened after just the 8th coat. We have tried sanding it out but no luck so what did we do wrong? And any suggestion on a fix would be greatly appreciated. I'm thinking start over but really don't want to do that. It might be important to mention that this has been done on the bench, in the garage with door closed.

I used Minwax spar on my side. I did only one thing a little different. After applying the varnish with a roller, I used a foam brush (wet the tip first) to even out the finish. Sound like you have bubbles. I had a few bumps on mine. used a straight edge razor like a plane and just carefully to shave off the high spot and just put on another coat.

[STORMRIDER151]

Air bubbles. We were trying very hard to avoid that but it makes sense. We were going to use the foam brushes at first but were told that they were not for varnish but for just smoothing things out is a good idea. The last coat we did on the one thats not too bad we did with spar spray cans. It's drying now and we'll see what it looks like in the morning. Thanks for the input we'll give it a try.

[jonw]

Another trick is to thin it with mineral spirits - it will go on smoother and tend to have fewer bubbles which will usually dissolve before it dries. It's also easier to apply with foam brushes.

[working on it]

jonw said:

It's also easier to apply with foam brushes

Not for me, all my foam brushes would fall off the handles when I was testing the mineral spirits/polyurethane mix. I switched to a bristle brush (it said ok to use with oil/solvent based product), and the test proceeded from there. I also had surface texture changes. I started with pre-sanded (150 grit) plywood, applied 2 coats of 50/50 mix, let dry a week, then used 2 coats of 100% poly. After another week interval, I sprayed (rattle can) 2 coats of TSC (Valspar) tractor enamel. I was not entirely pleased with the grain raised with each polyurethaning process, but hoped the enamel would fill and smooth the roughness. I presume that the poly swells the cells of wood as it displaces moisture, and waterproofs it. But, I don't want to sand away any of the waterproofing just for the sake of a smooth appearance either. So, I let the 2 coats of enamel dry, then used 150 grit to sand smooth the painted surface. Only a little poly was exposed. I resprayed with 2 more coats, and I'm happy with the results. Looks like painted wood, not 100% smooth, but that's what I want it to look like. For the actual , not test, poly and paint application, I will follow my test procedure except for using a roller or actual spray gun to apply the enamel topcoat(s). One initial coat of enamel, then sand, then 2 or 3 coats after the re-sanding. I'm painting the TTT in three different colors, so each area can be done separately, in stages. I always overbuy paint, so I envision a ready supply of touch up paint on hand.

[STORMRIDER151]

Well, we to everyones advice and so far ,so good. We are using wide foam brushs, and cut the spar down 2 to 1 with mineral spirits. The first thing we did though is a heavy sanding to remove the air bubbles that had already formed. That meant sanding down about 4 coats. This morning they look great. Just a few little spots that need a little TLC. Thanks for the help guy's

[mallymal]

Some folks have a bad habit of shaking tins of varnish - you see them walking around hardware stores shaking all the way to the checkout! That puts bubbles in big style... you should always stir not shake (the very opposite of our Mr Bond's Martini). Not suggesting YOU did this but if you did....

[STORMRIDER151]

No we have been very carefull not to shake the spar up and protect it from contamination. The guy at HD warned us about that. We gently stir it. We let the brushes drip into a seperate container too instead of running it across the rim. I had read where that will cause bubbles as well.