Hand Planed Surface - Harwax Oil Osmo

[Tetsuaiga]

I was wondering if anyone has applied harwax oil to hand planed surfaces.

I am trying wood wax finish extra thin on some cherry, currently testing a sanded piece and a planed so far the application seems to have gone the same for both and at this stage 3 days wiped on 3 coats now will wait to fully cure. They look almost identical.

The instructions say sand up to 240 furniture -150 max for flooring. I don't really understand why this is except for that marks/wear/scratches are less visible on duller more matt lower grit sanded floor.

Or is there some real difference in what is happening with the finish, does it perhaps work more effectively if it's sat inside the scratch sanding valleys?

Thanks

 

[katellwood]

I've used both standard osmo and extra thin with great success however, was advised to use extra thin on dense tropical hardwoods (in my case Iroko) as the standard takes an age to cure.

From what I'm led to believe if you sand to 240 on a floor it turns into a skating rink and can be dangerous

 

[Tetsuaiga]

Interesting, I'd like to use mine on a table top so imagine thats not such an issue, though you wouldnt want your plates sliding off a table either =P.

I do find it a bit odd that cherry and cedar were mixed in with a lot of dense tropical species for the WWFET but the product page says cherry is suited to it so I'm going along with it. I think it said the extractives that give it its colour make penetration harder.

 

[custard]

That’s an interesting question.

Osmo say that sanding higher than 220 grit closes up the grain which reduces the penetration of the finish. I think there’s some truth in this but visually it’s pretty marginal, at least at the grits anyone is likely to use.

I’ve heard it claimed that a plane can cut through individual wood cells and will therefore produce a superior surface to sanding. If there is such a benefit then it’s absolutely minute. I agree you can normally detect a planed surface with your fingertips. But that’s more due to the very shallow scalloping that even the flattest plane iron will impart.

Bottom line, sand to 220 grit or plane if you prefer, but it’s yet another woodworking rabbit hole and won't deliver a meaningful difference for most projects.

 

[Just4Fun]

I’ve heard it claimed that a plane can cut through individual wood cells and will therefore produce a superior surface to sanding. If there is such a benefit then it’s absolutely minute. I agree you can normally detect a planed surface with your fingertips. But that’s more due to the very shallow scalloping that even the flattest plane iron will impart.

I don't know why a plane produces a superior finish but I would support the claim that it does, and not because of scalloping. There seems to be glass-like feel after a plane that I don't get with sanding - at least on hard woods and assuming the plane is sharp. I always assumed this is because my planes are typically sharpened to a far higher grit level than any abrasive paper I would use on wood. To me it makes sense that this would create a correspondingly smoother surface, but I have no real facts to back that up.
One way to test this is to plane one side of a board, then sharpen the blade with a significantly finer sharpening medium and plane the other side. I think you can tell by feel which side is which (if you can't, why do we bother with the extra sharpening steps?) and since both sides were planed with the same iron this difference can't be down to scalloping.

 

[MikeG.]

I think perhaps that the shinier surface produced by planing or scraping is due to sanding pushing dust into pores in the wood surface. With a table-top or the like which I have sanded well, I'll almost always (unless it is being painted) do a very light scrape over the whole thing before applying the first coat of finish. So light that it doesn't produce shavings so much as dust and whisps. I think of this as cleaning the surface, not smoothing it.

 

[Phil Pascoe]

I seem to remember reading of a comparative test between sanded and planed surfaces which came to the conclusion that once finished there was no difference.

 

[custard]

I seem to remember reading of a comparative test between sanded and planed surfaces which came to the conclusion that once finished there was no difference.

By and large I'd agree with that, which is also the conclusion of the OP in the opening post.

But there's another twist to all this. If you're using say an oil finish then plane, scrape or sand; whatever takes your fancy. But if you're using a thin film finish which will require some interim sanding between coats, then planing rather than sanding becomes risky.

Those minute scallops I mentioned before are almost inevitable with a planed surface, which means it's all too easy to sand off the ridges between the scallops, and then you're straight back to bare wood. If you'd stained the work before hand then there'd be no option but to strip everything back to bare wood and start again. You don't have to do that too many times before you stick to the rule, a thin film finish never goes onto a planed surface.

I hit a related problem this morning. I've got three pieces of Curly Cherry furniture that are due for delivery by the end of this week. I passed the three tops through the drum sander to get the first 80 grit sanding done, then worked down through 120, 180, and 220 grits at the bench. When I applied a coat of Osmo it was obvious something was wrong. Look at that dark vertical line on the left hand side.

Going in close you can see the problem in more detail,

This particular top must have hesitated while going through the drum sander, only for a fraction of a second or I'd have spotted it, but it was enough to wear a minute hollow across the grain with deep 80 grit score lines in it, because of the slight hollow subsequent sanding passes with finer grits didn't remove it. Some errors you can forgive yourself. A flukey bit of timber or some contrary grain, that's just part of woodworking, but this was a stupid schoolboy error. Failing to pick up a flaw during the square inch by square inch inspection you should always do before applying any finish.

So there was no alternative but to dig out a card scraper, strip off the finish and correct the mistake.

After that it looked fine,

But I'm now behind schedule, so I'll be back in the workshop at ten tonight, applying the final coat that should have gone on this morning, and kicking myself for not being more diligent with finishing routines.

 

[danguru]

I block sand with 220 on a block of wood, the bigger the better. As I wear out a sheet of sandpaper I consider it getting finer so I finish that area with the tired out paper. Also i find some good advies on joineryplans website and they say to me this "Never use a new 220 paper unless using until it is worn out". I should preach 320 and 400 but I think they are too fine to true out a surface.