Does BLO do anything?

[Wade Lippman]

For 20 years I have been putting BLO on first and then a wipe on varnish. I know that BLO doesn't do much of anything, but it seems to me that if it does seep into the wood and harden, it should add some water resistance.

So what is the current thinking on this? Does BLO do anything at all?

[Jim Becker]

It's a misnomer to say that BLO "doesn't do anything"...it's a drying oil. It tends to enhance the look, adds color and yes, you can build multiple coats for a silky feeling finish. Yes, it's not "super durable", but it's a valid finish. Professor Dr SWMBO's cherry desk that I built in 1997 (my very first piece of furniture) was finished in BLO and wax and still looks "nearly new", other than a few dents.

Now using BLO before using an oil based wipe on varnish doesn't get you much because the oil based varnish will provide essentially a similar effect. It may be darker or lighter, depending on what kind of oil was used when the varnish was "cooked", but again, similar enhancements for grain and color as BLO. The BLO is not going to enhance the "hardness" of the resulting finish regimen over what a film finish will provide. Yes, it's a drying oil and it "hardens", but even multiple coats don't build up much of a "hard" layer. It's also good to know that oiling the wood doesn't have as deep a penetration as one might think...it's pretty minimal, but that's all that's needed to enjoy what benefits it provides.

Now if like me, you begin to use waterborne top coats that don't do much for the wood, starting with BLO and then a barrier coat of wax free shellac can be a very important part of the process...

[John TenEyck]

I look at BLO as a means of modifying color. It brings out the red tones in walnut and gives white oak a subtle aged look. As a finish, however, I don't think it offers much (read any real) protection.

John

[Ed Gibbons]

BLO helps pop the grain in curly maple.

[David Bolson]

I recently asked a similar question on LJ. I did my own test and found that, on bird's eye maple, there was absolutely no discernible difference between BLO followed by OSMO Top Oil and OSMO Top Oil alone. Grain was popped the same both ways.

David

[John TenEyck]

Pretty much any oil has the same effect of accentuating the grain. The only difference is in the color they may impart.

John

[David Bolson]

In the test that I did, I used the bird's eye maple, cherry and walnut. The maple showed zero difference. The cherry, so slight that I wasn't even sure that there was a difference. The walnut definitely got darker, but the piece that I tested on didn't have figure in it, so I don't know what the BLO would have done for that. Next time I have a project using walnut, I'll try the BLO/No BLO on a figured piece to see what happens.

[John TenEyck]

Here are some test results I did a few years ago on cherry and black walnut.

Left is Arm-R-Seal gloss, middle is Sealcoat Shellac then ARS, right is BLO + ARS on top, and BLO + SC + ARS on the bottom:



My conclusion is BLO blotches on cherry, and Sealcoat over BLO makes it even worse. Straight Arm-R-Seal is my choice on cherry.

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On black walnut. ARS gloss on the left, Sealcoat + ARS in the middle, BLO + ARS on the top and BLO + Sealcoat + ARS on the right:



My conclusion was BLO really brings out the red tones and contrast in black walnut. Further, Sealcoat + ARS is a loser unless you are after a pale look.

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Testing I just did on English Walnut:

TC's EM-8000CV on the left, Sealcoat + EM-8000 next, BLO + ARS on top and BLO + sealcoat + ARS on the bottom, and Danish Oil Dark Walnut + ARS on top and DODW + Sealcoat + ARS on the bottom of the righthand specimen.



My conclusion is EM-8000cv alone looks gray green, not attractive at all. Sealcoat under EM-8000cv really brings out the red/brown tones, almost as well as using the oils. BLO probably added the most contrast, especially under ARS. Danish Oil Dark Walnut produced the darkest overall specimen (no surprise really) and gave the richest look both under ARS and under Sealcoat + EM-8000cv. Overall, Sealcoat + EM8000cv gave the most bang for the effort, absolutely opposite of what I found with black walnut. However, BLO + ARS gave the brightest color contrasts and grain definition and that was consistent with what I found with black walnut.

And that's why you test on scrap.

John

[David Utterback]

Very nice info, John. Thanks!