BLO for "popping" the grain

[Frank Drew]

BLO seems to be very popular among members here, although it's rarely used, as far as I know, in professional cabinet or furniture making circles. I haven't used any, for anything, since high school art class, but posters here claim that when applied before any final finishes, it really makes the grain stand out (pop). I haven't found that shellac or a good oil or quality varnish applied over a carefully prepared surface lacks anything in beauty or grain enhancement (luster, visual appeal, "pop", whatever, etc.).

Has anyone done side by side sample comparisons, one with BLO as a starter under other finishes, and the other identical except omitting the BLO? If so, is there really a difference, apart from perhaps some darkening with the former?

[Chris Padilla]

It is a personal preference. BLO is a lot easier to apply than shellac or varnish. I can't apply shellac worth a darn unless I'm spraying it. BLO is more or less a colorant. It adds no real protection.

[Prashun Patel]

In fact, Jeff Jewitt has done this comparison - in response to the same question I asked on an FWW Shoptalk podcast. He applied several finishes on a white piece of paper (which was a proxy for wood, since they both have arguably similar cell structures). Products with oil in them (BLO and oil-based varnish) made the paper most translucent as measured by the ability to see through the paper to ink printing on the opposite side. Shellac and lacquer were only marinally 'worse', and water-based finishes were behind that.

I used to think that it was the amber color in oil-based finishes and BLO that accentuated grain differences and made the grain pop. The dark color DOES have a role to play in highlighting this, but the translucent effect is more achieved by a finish that (to over-simplify it) is able to allow more light to reflect deeper into the wood. It turns out oil does this very well.

BLO is used because it's cheap, and once dry, can usually be used under other finishes, and also adds some measure of color that only gets more amber over time.

From my own experience, I too am hard pressed to find a difference between shellac, and a good varnish. If I'm not in a rush, I often apply BLO just because (don't laugh) I like the ritual, the smell, and the color.

[Jim Becker]

For folks who are using oil based finishes, there's often no need for the oil as a first step. But for those of us who use water borne finishes for our top coats, we often want the "oil pop" and slight amber coloration on certain species. That's exactly why I use it for a lot of my work...

[John TenEyck]

I did some comparative testing on cherry and walnut.

Left = Arm-R-Seal Gloss
Middle = Arm-R-Seal over Sealcoat shellac
Right = Arm-R-Seal over BLO. Bottom half has SealCoat over the BLO, then Arm-R-Seal

Cherry:

IMG_3527.JPG

Black Walnut:

IMG_3526.JPG

IMO, the BLO caused blotching on the cherry. On the walnut it did, indeed, add more depth and contrast, and also added a reddish tone. I really liked the result. What I hate about BLO, however, is that it takes forever to dry/cure, if it ever really does. When I made the specimens the BLO was still tacky after 2 days. That's why I tried sealing it with the SealCoat, which I had read about several places, and it worked great. I was able to move on to the finish coats within an hour after applying the SealCoat and found no long term problems. If I do use BLO on a future project, I would apply it as sparingly as possible, let it sit 24 hours, seal it with dewaxed shellac, and then apply my finish coats.

John

[Jim Becker]

John, when using BLO for "character enhancement", you only put on the lightest of light applications and rub off any excess immediately. And believe it or not, if you really have a deadline, you can apply the SealCoat even a few hours later followed by top coats. I've done this a number of times with great success after reading an article about the same by a well known finishing expert somewhere.

Oh, and one man's "blotch" is another man's beautiful figure. LOL

[Chris Padilla]

John,

I'm curious to what final grit those sample boards were sanded to? 180 perhaps?

[John TenEyck]

John,

I'm curious to what final grit those sample boards were sanded to? 180 perhaps?

Chris, I'm not sure if it was 180 or 220 grit. One of the two.

John

[Art Mann]

The degree to which a work piece is sanded certainly makes a big difference in how well stain, dye or in this case BLO is absorbed. It is quite possible in my limited experience to sand too smooth.

[Kent A Bathurst]

John, when using BLO for "character enhancement", you only put on the lightest of light applications and rub off any excess immediately. And believe it or not, if you really have a deadline, you can apply the SealCoat even a few hours later followed by top coats. I've done this a number of times with great success after reading an article about the same by a well known finishing expert somewhere.

Precisely. On figured wood, I do it all the time. Just barely dampen a cotton rag with BLO out of the can - block the spout, turn the can and turn it back - rub like heck, dampen a little more, move on to the next area, rinse, repeat. Put down the barest possible even film. You can go after it with a shellac seal coat in 15 min.

I haven't worked with cherry in 12+ years. No insight there. It makes a visible difference in "enhancing" the grain.

I used BLO as a primary finish one time - my very first build: my workbench out of reclaimed 125 year-old RO. 15 years ago. First coat thinned to soak into the wood. I swear that stuff is still leaching out. Never again.

[Jim Becker]

I used BLO as a primary finish one time - my very first build: my workbench out of reclaimed 125 year-old RO. 15 years ago. First coat thinned to soak into the wood. I swear that stuff is still leaching out. Never again.

That's not sounding right...perhaps it was inadvertently raw linseed oil (doesn't dry) or was "old" or defective finish. (have to be careful with wide pore woods like oak, ash, etc., however for this) I've never had that happy and have finished a number of projects with just oil and wax...including my wife's cherry desk in 1998 or so. It's still going strong!

BLO is a drying oil. Most of it even has metallic dryers in it. (Tried and True is one exception as it uses a different method to obtain drying) When properly applied with a very light coat, it shouldn't leach out at all...

[Mel Fulks]

I agree , Frank. It's always seemed strange to me that so many like it when conservators say it breaks down and causes
splotchiness. It's been used for a long time because it's been available for a long time , not because it was thought to be superior. I've done my own tests with other
oils ,including motor oil, and think they all work as well as linseed oil.

[Rick Mosher]

I find the secret to popping the grain on any species of wood is to shear the fibers by using a cabinet scraper or hand plane as opposed to sanding.
walnut.jpg
The left side of this figured walnut board is sanded the right side planed and scraped. (This is just raw wood no finish and you can obviously see the difference)
On figured wood you can also create a color pop as well by staining the softer wood a different color than the harder wood.

[Howard Acheson]

It's the amber color in BLO that causes the grain to "pop". It make little or no difference what treatment is used to impart the amber color. BLO, amber shellac, oil based poly or non-poly varnish, lacquer or tinted waterborne clear finish all will all provide almost similar results.

[Prashun Patel]

(respectfully), If by 'pop' we're all just referring to accentuating surface differences in the wood, then I agree it's more about color. However, if we mean making the wood appear shimmery or 3-d or irridescent, then I think the optical characteristics of the finish plays a significant role as well. At least, this is what my own trials have convinced me of.