I picked up a half pint can of Osmo Polyx satin (3043) to try from Lee Valley, and I thought I would share my observations and impressions. In addition to the helpful video referenced above I also found this video useful:
https://www.youtube.com/watch?v=wGGGwHzPu64
And printable instructions here:
http://www.raincoastalternatives.com/files/3613/1810/6146/3054Furniturev2.1_HOW_TO.pdf
Unfortunately there doesn’t seem to be a lot of guidance from Osmo on how to apply it to small objects, and my goal for a wood surface differs from what’s customary for furniture making and is way different than finishing floors. So I was unsure how Polyx would work for me. I am looking for a hyper-smooth surface, which preserves the wood look. To get to where I want to be I sand the wood to at least P600, but recently P1200 and even P3000. So the performance I observed may not entirely reflect what others will see.
I should also mention that my finishing area is smack in the middle of the work bench in my dusty shop and other than running the overhead air cleaner for a couple of hours or waiting till the morning for finish applications I make no other preparations.
I compared the Osmo Polyx with Bartley Gel Stain Clear Coat, which is what I usually use on my pieces. The Bartley product is a satin sheen oil based varnish, and as near as I can figure out a polyurethane alkyd resin blend. I started off with a small scrap board of clear maple, about 4 x 8 inches. I also had a cherry burl bowl I recently finished turning that I was willing to risk. The cherry bowl and maple scrap were both sanded to P1200. For comparison purposes I had three turned pieces that were already done with the Bartley finish. The first was from spalted maple and sanded to P1200; the second was from the same clear maple that had produced the scrap board, but this piece had only been sanded to P600. Last I had a finished cherry piece which had been sanded to P3000.
When I opened the can I was struck by the resemblance of the Polyx in consistency to the fat laden liquid released when you carve a roasted chicken or turkey. There is a vague odor, but not particularly unpleasant, smells sort of like candle wax. Osmo spreads, or should I say smears, easily and is somewhat self leveling so it lends itself to application with a white “non-abrasive” pad. As opposed to the colored pads, the white pads contain no additional abrasives and are the equivalent of 0000 steel wool. I have to say I was skeptical of using the pad because nothing that looks like it could scour a pot is non-abrasive enough for me to want to rub all over something I’ve sanded that smooth. But it worked fine. It certainly consumed less of the material than a rag would have done. Still next time I might try some other applicator.
I applied tiny amounts at a time and it spread remarkably far, not unlike one would expect, say from chicken fat. Once spread around I then went over the entire application area a second time, re-spreading without adding more material. As to scrubbing or pressing the Polyx into the wood, that did not seem to be necessary. I used moderately firm pressure.
With my first coating on the bowl I did the inside and outside together in one go. Thing is you’ve a moderately heavy bowl with a very smooth surface that is now covered in chicken fat. You want to be mindful of your grip. I decided to take the second coat one side at a time.
After the spreading the finish the surface looks good, but there will be some visible streaking. I let it sit for 10 to 20 minutes, then I wiped and buffed by hand with a clean cotton rag. As you begin to wipe with the rag there is fairly high friction. This dissipates quickly as the surface becomes smoothed. After buffing the surface looks great, but the coating has not set up yet. I’ve heard different numbers, but the instructions I found call for a 12 hour cure between coats. I applied two coats and there is no sanding between coats.
So how does this compare to the application process for Bartley? The Bartley Gel varnish is very high viscosity, about like pudding, and much thicker than General Finishes’ gel varnish. It is a straight forward 3 rag application: wipe on; wipe off; moderately vigorous hand buffing. All steps are done one after the other, no waiting. Cure between coats is 6 hours. There is no sanding between coats. I typically apply 3 coats, but the third does very little.
So actually, I have to give the ease of application edge to Bartley. I do not have to wait 20 minutes for the buff step, and with a 6 hour cure I can theoretically get three coats on in one day, if the first coat is done early enough in the morning. Now I may not have the Osmo application process dialed in, there is a lot of variation in instructions out there and next to no one is actually talking about how to apply to handheld objects, but it does seem to need to dry a bit before buffing. And I have noticed some lingering smell on the cherry burl even after a day (that may be related to it being burl), but I’m not sure whether or not you can re-coat sooner than 12 hours.
So how good is the finished surface?
The Osmo on P1200 clear maple results in a super smooth, satin gloss, flawless dust nib free surface, that feels silky smooth and down right sensuous to the gliding finger tip.
The Bartley on P1200 spalted maple results in a super smooth, satin gloss, flawless dust nib free surface, that feels silky smooth and down right sensuous to the gliding finger tip.
Comparing the test board to P600 clear maple, the Bartley is noticeably more amber where the test board of Osmo is clear. The P1200 Osmo is smoother.
The two cherry pieces also compare similarly. The P3000 piece may be ever so slightly smoother, but I really couldn’t tell much difference. Ambering is harder to appreciate.
I was expecting something special from the Osmo. Color was the main difference, but I really couldn’t see or feel much difference in sheen or smoothness. My thinking is that surface smoothness is multi-factorial and at these fine grits sanding is the more powerful factor. Quite possibly I would appreciate a smoothness difference if the surfaces were prepped to 220. I think that it is quite possible that once set up the Osmo surface has less sliding friction than the polyurethane varnish. But any difference appears lost in this setting.
It’s worth noting that neither product had a problem with dust nibs, so there is no need to sand between coats. I think this insensitivity to nibs is because neither is particularly tacky after the application process is complete. In the case of the Bartley I believe this is because it is so viscous to begin with that there is not a lot of solvent that needs to evaporate before it begins to set up. In fact it is usually dry to the touch in an hour or so. Maybe something similar is happening with the Osmo product. I will say that with both products there is a limited working time. For large projects your best to do small (2’ x 2’) areas at a time. Now, if you feel morally compelled to sand between coats it’s possible to do so with either product. Sanding a surface coating is just something I do not want to have to deal with. I’ve tried GF ARS, High Performance and Wood Turner’s Finish. They are all highly nib-o-philic.
So that’s my story. I think the principle difference between the Osmo and Bartley products is that Bartley is a little easier/faster to apply while Osmo causes less ambering (and may be easier to repair). What’s not clear to me is how much of an effect hyper-sanding might have had on these results. In this setting both deliver very pleasing results and I think it’s hard to choose. I could be happy using either.