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Hi, new varnisher here. When I brush it on carefully, I can see tiny
gas bubbles forming in the wake of the brushstroke. Most of them pop
but some do not and others seem to form during the drying process. The
more I try and brush it out the worse it gets. The unhappy result is a
beautiful piece of wood with assorted pimples strewn about the finish.
I have tried expensive brushes and foam brushes with the same result.
I have tried straight varnish, thinner, cheap and dear and 216
(xylene) as brushing agents. I follow the routine from the Brightwork
Companion as well as I can. Not shaking or redipping from the can.
I'm working indoors with everything at room temp. I have used brand
new Schooner Varnish, some old junk in a can and a custom artists
mixture of Danar (Damar?) and magic emollients etc. They all act the
same. It's less noticeable on 25 year old teak than on newly made
woodwork but it's the same result even after 8 coats. I sand out the
flaws between coats. I am definitely open to suggestion at this point.
Gosh, the old teak just takes your breath away. If I can just take
care of this complexion problem.
Thank you.

In my not inconsiderable experience with wood finishes I have to note
that varnish is one pain in the butt finish to apply when compared to
many other finishes. Unfortunately, with bright work, the options I have
open to me for other applications aren't viable.

First, gloss varnish doesn't need to be mixed. Semi and satin does.
Never shake the can, stir gently to avoid suspending air bubbles in the
finish before you even start applying it.

Thin your first coat or two by 50% and apply it with a rag.

If you use a brush be sure it is a natural hair brush, badger, and do
not tap off the excess into the can. Gently move the brush across the
mouth of the can to get excess finish off.

Thin the varnish to around 15% for follow up coats. The less viscous
coat allows air bubbles to escape faster.

Start you brush stroke with the brush tip and held almost vertically to
the surface being coated. Draw the brush slowly across the surface
lowering the angle of the brush as the varnish flows out.

Tip off the coat. That is, once you have the stroke finished very gently
and with just the tip of the brush touching the finish at 90 degrees
move it across the finish to knock out any bubbles you do get.

DO NOT over work the finish. It is almost impossible to not get some air
bubbles in the finish. As you have found, overworking the finish just
makes matters worse. That is what they make sandpaper for.

DO NOT try to sand off drips and sags. Use a sharp chisel or razor to
shave them off.

If at all possible DO NOT varnish in full sun. This causes the finish to
skin over much too fast to allow any air trapped in the grain of the
wood or laid down by the brush to escape.

DO NOT apply thick coats. Thin coats are best! Thick coats also slow the
rising air bubbles to the point where they become trapped in the curing
varnish.

DO Not bury bubbles and dust bumps under another coat. Sand them out
before the next coat. Waiting, of course till the coat is cured at least
eight hours. If I am using an oil based varnish steel wool is my
preferred medium for doing that job. If you are using water based
varnish steel wool is ok for the last coat but you have to use sandpaper
for the in between coats.

Decant the varnish to another container for application. Do not put your
brush into your main supply or dump anything left in the second
container back into your main supply. Doing either will contaminate your
main supply with anything your brush picks up. Pour slowly to avoid
introducing bubbles into the varnish.

Thin coats means you have to apply more of them which takes more time
but they avoid a lot of the problems inherent in applying varnish.

My preferred method of applying varnish is to head down to Lowe's or
Home Depot and pick up a large box of Scott's "Rags in a Box" wipe on
the above mentioned fifty percent thinned coats then thin the varnish
somewhere between fifteen to twenty percent, the figure isn't critical,
and wipe on the rest of the coats.

While the above method, what with thin coats and drying time between
coats, takes more time to get a good build then brushing on a few heavy
coats it avoids most of the problems brushing on heavy coats introduces,
air bubbles, drips and sags, dust collection, and can, if one is looking
for a really good finish, actually reduce the time it takes to get one
since you aren't trying to fix those problems.

The use of thin coats makes no difference in the durability of the final
finish.

I may have forgotten a few things there but it's somewhere to start.

Hope it helps
Mike G.
--
Mike G.
Heirloom Woods

www.heirloom-woods.net