# Experimenting with tinted varnish



## keress (Apr 4, 2015)

I've been playing with a technique I cooked up some years ago. I'd sanded a hardwood floor and had a section the dog had peed on years earlier that was blackened. I was pickling the floor so it was very noticeable. I've done a fair amount of painting as in artist painting, so I got down on the floor and painted some wood grain over the stain with acrylic paint, since I was using water-based finish.

I'm experimenting again. I've got an old table with a butcher block top. Someone gave me a china cabinet in a medium stain. I've redone the chairs so the unpainted wood matches the cabinet. It's an odd wood, I suspect tropical that stains very poorly. There are dark flecks in the wood that show up prominently when stained, and it's splotchy in general. I used the technique above to get the wood to look like a better grade of wood that stains nicely. 

I used Wonderfill eventually to eliminate the splotchiness and the table top did stain better than the other pieces, with just a few areas I needed to correct. But, that all said, now that I look at it, it's redder than the other pieces. I tried adding some artist's oil color to the spar varnish. (I went with oil color since I'd used Minwax oil stain.) 

It did not work well and I wound up wiping it off with mineral spirits. In doing so I noticed that I had much better control in blending all the wood to have an equal amount of the color in the tinted varnish. So I cut the varnish with mineral spirits by about half and was able to quickly add a thin layer of color. I think one more pass and I will have all the pieces matching well enough.

My question is, what is the effect of using several thinned layers on top of two denser layers? In oil painting (as in artist's painting pictures on canvas) there's advice to put fat over lean to avoid cracking. I'm doing the opposite here. Is this finish likely to fail in a year or two?

What are the characteristics of thinned varnish? Does it take longer to dry? Should I allow more time between coats? Anybody have any opinions/experience with this.


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## Steve Neul (Sep 2, 2011)

What kind of wood is the butcher block top made of? Many species of wood will stain blotchy and ugly if you don't pre-treat the wood with a wood conditioner. 

As far as putting color in a oil based finish you can just buy polyshades. It is just polyurethane with pigmented added. If your project is interior you would be better off using an oil based polyurethane than a spar varnish. A spar varnish is made softer and more elastic to deal with the temperature changes of being outdoors. A polyurethane would make a harder more durable finish. 

What are you using for color? If it is straight pigment you can create adhesion problems unless you add it to a binder like varnish. 

Artist oil paint is a different medium that what you are doing, especially over wood. What every you apply it needs to be completely dry before applying another coat. The top layer will certainly crack if you paint over a finish that hadn't dried. If what you are doing is very thick you might have to wait until one layer is cured completely before applying another. This would mean a month between coats. 

Varnish will take longer to dry if thinned. Varnish is a mixture of drying oils like linseed oil and tung oil and other resins and if you thin it the solvent has to evaporate before the oils begin to dry. Still in warm weather a oil based varnish should dry enough to recoat after drying overnight. If the weather is cool and or damp it could take a couple days between coats. If you can press your finger on the finish and leave a fingerprint in the finish then it's not near dry enough. The finish should be dry enough you can sand it and it makes dust.


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## keress (Apr 4, 2015)

Thanks for the reply. I am already too far along this project to switch from the spar varnish. I didn't care for the polyshades. It was very difficult to avoid overlaps in color, the same problem I was having until I thinned the tinted varnish I'd concocted. From what I've been able to research, it appears that artist oil colors are basically just pigment and linseed oil (or the equivalent). The main difference is that spar varnish has drying agents. 

So far the project is looking great. I got the color matching I wanted, having access to the artist colors gave me the flexibility I needed to get just the right pigment, and the mineral spirits gave me to open time I needed to get it all blended uniformly. I'm really intrigued with how much of a difference thinning a finish can make in getting a really smooth application.

The table was a lost cause otherwise, so if it fails down the road I'll just get out the old belt sander and try again. 

Would it be advisable to put a harder oil-based polyurethane as a top coat? I have a feeling not. There isn't any army of kids abusing the table anymore, I think I'll be all right with the spar varnish.


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## Steve Neul (Sep 2, 2011)

keress said:


> Thanks for the reply. I am already too far along this project to switch from the spar varnish. I didn't care for the polyshades. It was very difficult to avoid overlaps in color, the same problem I was having until I thinned the tinted varnish I'd concocted. From what I've been able to research, it appears that artist oil colors are basically just pigment and linseed oil (or the equivalent). The main difference is that spar varnish has drying agents.
> 
> So far the project is looking great. I got the color matching I wanted, having access to the artist colors gave me the flexibility I needed to get just the right pigment, and the mineral spirits gave me to open time I needed to get it all blended uniformly. I'm really intrigued with how much of a difference thinning a finish can make in getting a really smooth application.
> 
> ...


The polyshades may have had too much pigmented for you. If you were having too much trouble with it overlapping the color you could have thinned it with clear polyurethane. Yes, artist paint is linseed oil and pigment. A spar varnish has these ingredients too only thinned more however it also has phenol formaldehyde resins to make more of a finish out of it. These resins are not as hard as the polymer and urethane resins included in polyurethane. 

The spar varnish will work alright for you but you will have to expect the finish to scratch and damage easier than if you had used polyurethane. Once the finish has fully cured there won't be a huge difference in the hardness. 

In the event you end up taking the finish off it's always best to use a chemical remover rather than sanding. Sanding tends to remove what is on the surface and doesn't remove what has penetrated into the wood. Then when you apply stain there tends to be spots that won't accept the stain because the wood is still sealed with the old finish.


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## keress (Apr 4, 2015)

Here's somebody talking about thinning varnish the way I've been playing with it.

http://www.thewoodwhisperer.com/articles/a-better-way-to-apply-spar-urethane/


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## Steve Neul (Sep 2, 2011)

In my opinion and experience thinning a varnish 50% is counterproductive with the exception of the first coat on raw wood. Thinning that much makes the varnish take too long to dry and screws with the sheen and integrity of the finish. For the most part brush marks in varnish are caused by either using a brush that is too coarse or brushing too much. When brushing a varnish it's important to use a very silky soft brush and apply the varnish as thin as possible with as few brush strokes as possible. The more the finish is brushed it introduces more air in the finish and causes it to set up before it flows out.


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