Varnish thinning percent

[aaronwindward]

The manufacturer recommends thinning varnish by 50% in the first application. If I'm starting with 4 oz of varnish, does this mean I should add 50% of the original volume (2 oz), or 50% of the final volume (4 oz)?

I googled thinning in general, and I found one website that claims its P% of the original, and other that claims that 50% is "half and half." Who is right?

[deniseO30]

I just thin til it's "water" like. not rocket science, sand between coats. it takes 3-6 coats to fill the grain and get real smooth. Done right it can be glass like in finish.

[billyruffn]

What's important is that the varnish soak into the wood. I don't think the exact mixture is terribly important at this stage of the project. The thinner is is the easier it will find its way into the pours of the teak. You'll need to do several coats of the thinned product before moving up to near full strength.

Tricks I learned from a West Indian rasta-man varnisher (he'd kill me if he knew I was sharing his secrets): He only uses Epifanes varnishes and he cuts it with Interlux 333 in a mix of a cap full of 333 to 3 oz or so of varnish -- the exact mix is "art" and requires a "sense" of how the drip should come off a stir stick. He puts the varnish in the frig for a while before he thins it. (My take on this is that he cools the product to slow the evaporation of solvents and increase the "float" time, and he thins the cooled varnish to increase it's flow-ability). He'll use either a high quality ($40) 1/1/2" badger brush or a $1 1 1/2" foam brush. Your choice, but he never seems to get the $40 brush clean enough so that it won't leave dust in the final coat after it's been used once. If he wasn't so short of cash, he'd probably have his own brushes which he'd keep soaking in diesel between jobs.

He uses varying grades of fine sand paper as the coats progress and he's a stickler for dust prevention. Inside the boat he'll wet sand everything to prevent dust from arising. He cleans everything, including the surrounding areas with water before he starts applying varnish. Hatches are closed, fans are off and people are kept out of the boat while varnish is wet.

Also, please note that it's important to have Marley tunes blasting in the background and to sing the lyrics at the top of your voice while applying varnish. I think the vibrations of the music help shake the floating varnish smooth. A few totes of ganja probably help to steady the brush stroke, but I've never seen it done, so who knows?

Good luck with your project and remember -- Varnish is Art, some would say Black Magic.

[tomperanteau]

So how do you folks feel about Polyurethane varnish? We've had good results with it so far.

[deniseO30]

tom I use them both. Traditional varnish will get dark with age. the poly's don't seem to get dark ever. Poly is much harder.

[Omatako]

In my experience traditional varnishes seem to resist UV better, I find that all the external work I do seems to last better with ordinary varnish.

The only time I thin varnish is when I am varnishing tricky areas (not flat) then I use an air brush for the last two coats and it has to be thinned about 60% When brushed on, it goes on neat.

I also don't use expensive brushes. I use a reasonable quality brush, I don't wash it between coats but rather lay it up in masking tape to make it airtight. That way the brush stays moist and usable for long enough to allow each coat to dry properly. At the end of the job (often up to 10 coats) the brush goes in the bin. I find the amount of turps required to clean a brush properly exceeds the cost of the brush.

[JimsCAL]

Originally Posted by billyruffn

Also, please note that it's important to have Marley tunes blasting in the background and to sing the lyrics at the top of your voice while applying varnish. I think the vibrations of the music help shake the floating varnish smooth. A few totes of ganja probably help to steady the brush stroke, but I've never seen it done, so who knows?

Funny!!!

[Flybyknight]

In my other life I was a paint chemist. 50% is intended to mean 1/2 of the original. Mineral spirits is a diluent, where as turpentine and VMP Naphtha are solvents. Solvents lower the viscosity much more efficiently than equivalent volumes of mineral spirits.
Most varnishes today are junk. The original high quality was a phenolic
varnish, not the cheap alkyd you find today.
Never use a quality badger hair brush for the 1st. time on quality work! Yes, a badger hair brush needs to be broken in.
You need to learn how to clean paint brushes from an experienced painter. Too complicated for this reply.
Avoid high humidity and water, as that will cause the finish to blush meaning a white cloudy appearance.
Hope this helps.
PM me if you really want to know how to clean a paint brush.
Dick

[SJ34]

50/50 varnish and thinner for first coat then lower percentages on subsequent coats until straight (if you're very good with a brush). The purpose of thinning the first coat this much is to saturate the wood, this is especially important with teak (oily and repels finishes) and mahogany (lots of open grain that full strength varnish won't saturate fully). Some pros will even use 75% thinner 25% varnish for the very first coat. I think that is overkill.

It is very important to let the solvents completely flash off and allow the wood to lighten up before adding additional coats.

Varnishing is an art form and done properly is stunning to look at.