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Being somewhat new to hobby woodworking, I have only used finishes straight out of the can. I have read on here about people diluting oils and other finishes with various thinners. I am wondering what this accomplishes and why it is done. It seems that with most people the most dreaded part of woodworking is sanding. I'm finding this isn't true for me. I don't mind sanding as much as I dislike finishing but I want to have great looking results:blink:.

Like I said, I have only used stuff right out of the can. That has been limited to Minwax stains and fast dry polyurethanes and Sunnyside brand boiled linseed oil. I have only used paint thinner to clean brushes but want to learn more about finishing. Thanks for any help.
 

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I would say most commonly people thin their finishes for two main reasons.

1) To use in an HVLP sprayer (high-volume low pressure). Because as the name says, these sprayers are low pressure it is more difficult for them to push thick oil paints/finishes and require thinning to work properly. They push a high volume of air to atomize the liquid so it applies evenly. In order for it to do this it needs to be nice a thin, basically.

2) To apply a "sealer" coat or to customize the finish. Usually a sealer coat is the first coat and is a very thin coat which is lightly sanded. This provides a smooth base for later coats and usually prevents the wood from sucking up finish unevenly. Consequently, the higher the solvent to solid ratio, the faster the coat dries as the volatile solvent evaporates quickly. Otherwise, some people just like to add a little more solvent because they like to work with a thinner product (prefer how it feels when they apply it), want to put on thinner coats, or think it flows and levels better. Usually thinning will make the product level out better, especially if you're using a brush to apply and don't want brush strokes.
 

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In addition to what Talespin said: I thin BLO for one reason, it's just easier to handle. The application and wiping off are both just a little friendlier when it's thinned. That's one of the reasons I thin varnish (I don't use polyurethane varnishes, only alkyd or phenolic resin formulas). Besides the leveling out stuff mentioned it makes it a little easier. As for your question about learning more, I highly recommend Bob Flexner's book. It's easy reading, I read mine much like a novel just starting in the front and going through. Another choice that has the same info arranged in a different fashion would be Jeff Jewitt's book. I find his to be a little more technical (on formulations and the finish chemistry) and more suited to being used like a reference book, where you look particular subjects up. Both are excellent, and I think one of the them, or both, should be required material in any hobbyist WW'ing shop.
 
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