Raising grain -> unbalance?

[Dan Stromberg]

Good morning all,

Hope everyone had a great Thanksgiving weekend. I've recently started trying to incorporate raising the grain in bowls I make that I expect to get wet. My normal workflow is to turn and finish the outside with the piece held with a screw chuck, then reverse to hold with a regular 4-jaw chuck and do the same on the inside. I sand to about 220, then spritz with water, let dry, re-do the 220 grit and go up from there.

What I've found for the past couple of pieces is after wetting the inside of the bowl, the piece seems to turn wildly out of balance, almost as if I had given it a big whack and un-seated it in the chuck. Re-sanding gets things pretty close to true again.

In principle, I get it - the side grain would expand more than the end grain, which could sort of explain it, although I'm surprised by how much out of balance it gets.

Is this normal, or is something else going on? And is there a better approach for raising the grain than what I am doing? Wondering if I should finish inside and out at the same time, instead of doing the outside before reversing.

Thanks for any input!

Dan

 

[Michael Anderson]

Do you leave it in the chuck when you spritz with water? Or do you remove and then re-chuck? If the latter, it might be a re-chucking issue. Just eliminating possibilities. I've never noticed that a bowl wil get wildly out of alignment when water popped. (aside from some very thin walled bowls, like 1-2 mm). How thick are your walls, and how much water are you using?

 

[Marc Banka]

When you wet the bowl it wants to go back to its preseasoned state. Usually, for me anyway, it goes back to where you were once dried. I think you’re wetting too much If the piece is moving.

I wet a shop paper towel, good and wet, and wipe the surface quickly. Give it enough time to dry, blow air at it to speed things. Then sand. Don’t soak the wood.

 

[Dan Stromberg]

Do you leave it in the chuck when you spritz with water? Or do you remove and then re-chuck? If the latter, it might be a re-chucking issue. Just eliminating possibilities. I've never noticed that a bowl wil get wildly out of alignment when water popped. (aside from some very thin walled bowls, like 1-2 mm). How thick are your walls, and how much water are you using?

Left it in the chuck. The walls aren't terribly thin - maybe 1/4 inch or so. I've basically been spritzing the bowl directly.

When you wet the bowl it wants to go back to its preseasoned state. Usually, for me anyway, it goes back to where you were once dried. I think you’re wetting too much If the piece is moving.

I wet a shop paper towel, good and wet, and wipe the surface quickly. Give it enough time to dry, blow air at it to speed things. Then sand. Don’t soak the wood.

That sounds like it could be the key! As I said above, I've been spritzing the bowl, getting it "good and wet", then giving it a few minutes to dry. If I saw a dry spot, I spritzed some more. I wouldn't say I soaked the wood by any stretch, but I did try to make sure I got it all. I'll give the next one the shop towel treatment.

 

[Richard Coers]

Depends on how much water you use. A barely damp cloth is what I use. I wouldn't even call it wetting in my case. All I'm trying to do is raise some grain, not wash out the bowl.

 

[Dan Stromberg]

Sounds like this is the same mistake I have been known to make with finish too - a little too heavy with the application. I will definitely give it another shot...

 

[Alan Weinberg]

great advice. I guess I’ve been using too much water also.

 

[robo hippy]

I have heard of people soaking pieces of wood for days in order to get it to warp back to regular/normal position. I would guess that if you turned very thin, like less than 1/8 inch, adding dampness to the wood could make it warp at least a little. For 'raising' the grain, just get it damp, either with a damp rag, or spritzing with a spray bottle.

robo hippy