Wipe on poly

[Mark Rainey]

Using Minwax wipe on poly ( oil based ) on cherry. Fine Woodworking has several positive reviews in the past. Seems very easy to use. First coat wiped on lightly, not much more than wetting the surface. It looks like it is dry in 15 minutes, but waited 2 hours. Wiped on another coat, dried in 15 minutes again, but waited almost 2 hours. Wiped on 3rd coat and called it a day. Following day noted some finish build up - good because not much after the first 2 coats. Light sanding with 320 stearated sandpaper. Got very smooth. But noted scratches from sanding even though it was light and I vacuumed paper frequently to clear. Three more coats the next day, spaced out several hours. Nice finish. Those scratches seem to disappear. Went with 400 stearated and very, very light sanding - one light swipe with vacuuming after each swipe. Scratches!. Following day 3 more coats. Beautiful gloss finish. But looking very closely I can see some of those scratches remaining. My family doesn't notice them. I am really wondering about this sanding business and scratches. In a past project I even used mineral spirits with sanding and I still got scratches. I have seen others questioning this phenomenon. Thoughts?

[Jamie Buxton]

For sanding near the final coats, I use really fine sandpaper -- 800 or even 1200. All you're trying to do is to knock off dust nibs, and the super fine grit can do that. The super fine grit must leave scratches, but they're too small to see. With 1200 you can even de-nib the final coat without changing the sheen. (I mix Minwax Wipe On gloss with satin in a 50:50 mix to get a semi-gloss sheen.)

[Frederick Skelly]

I sand between later coats with a paper that closely resembles a brown paper bag. I buy it at the BORG in a big roll. (I even use it for stropping plane irons occasionally.)

[Prashun Patel]

Your scratches can be from a couple things. Sometimes the scratches from the lower grits aren’t removed properly and then show up only when the surface starts to build a sheen. Sometimes once a film forms, if it is soft, even the finer grits can cause Corning and gouge the surface.

Assuming neither of these are your issue, then it is likely the case that you don’t have enough of a film to fill in the scratches of the 400 grit. It can often take 2 to 3 coats after sanding with 400 to get an even sheen again.

The trick to eliminating scratches is to not sand much at all in between coats.

For my part, I usually sand up to 600 and then in between coats with 600 or higher only if my fingers tell me so. And I leave a day before doing it (for wipe on poly). I sand lightly and use my fingers - not eyes as a guide. This way I sand much less.

[Mark Rainey]

Jamie, Fred, Prashun, thank you for the advice. I will try your approaches. Prashun, yes, I think it is worth making sure I wait long enough for hardening of the finish.

[Rich Engelhardt]

Make sure you use a good firm sanding block. You need to apply even pressure.
I'm not a fan of any of the fancy padded blocks. I just use a scrap of wood.
YMMV on this. Uniformity across the block is what matters.