Sanding marks

[Jim Underwood]

It seems no matter how much time I spend sanding and working my way up through the grits, I miss some sanding lines somewhere along the line, and don't notice until I have a coat of finish on it, get the thing off the lathe, and take it in the house.:mad:

Any hints on how to spot those things before I get it off the lathe?:confused:

[Troy Donson]

Jim, just to see what I have missed, I take a paper towel get it wet (not damp, but not sopping either - just wet) with mineral spirits and wipe the whole piece down and using a _bright_ flourescent lamp held at an angle slowly turn the piece. I also use one of those lighted magnifiers like you see in crime labs for an even closer look... let the piece dry thoroughly (about 15 seconds here in AZ) and then apply your finish.

For me this method seems to work best. I learned it from an ancient custom car painter. Flourescent lights just seem to show defects and sanding marks better, especially when held at an angle to the peice.


Hope this helps,

Troy

[Don McIvor]

Don'tcha hate getting ready to unchuck a project, only to discover those sanding swirls? I read another thread where as I recall someone suggested coating the piece with naptha (I think--maybe someone else can verify) to reveal scratch marks.

I had more trouble with sanding marks before I switched brands of sandpaper, so you might experiment with that variable. I'm now using Klingspor's cloth-backed paper and am pretty pleased with the results. There are probably other options and maybe some other turners can offer their favorites up. The experience of switching sandpaper suggests you get what you pay for in this arena, and in my mind the extra cost of the Klingspor is worth the longer useful life of the paper and better sanding results.

You might also try sanding with the grain (and the lathe off) between changes in sandpaper grit. I go to this extra step when the finish on the piece is absolutely critical.

[Geoff Hanha]

Poor lighting is the bigest problem, i have changed my lighting i have a double floresent fitting over my lathe with a natural daylight tubes in it, also for the tubes to work propley you need to have the defuser fitted, i used to go up the house and give it to the wife and ask what she thought and it would be you have some marks, WHAT bad lighting:mad:, change your lighting, if you sand right then its the only other way..we buy good tools and forget the lighting most of the time,, Geoff

[Scott Lux]

let the piece dry thoroughly (about 15 seconds here in AZ)

Let's see, 15 seconds in AZ. It's Springtime in Ohio. That would work out to about 4 months to dry. :D

[Jim Underwood]

Well dang. I have pretty good lighting in my shop. It's a 16 x 24, and I have two rows of two florescent lights and one row of four incandescent lights in between. In addition I have a 250W Halogen work lamp and an incandescent work lamp shining on the lathe.:eek:

Isn't it enough?:rolleyes:

Thanks for all the tips. I'm going to try out the mineral spirits trick next time. It may even help with the sanding.

Any more?

[Barry Elder]

Well dang, Jim! If your lighting is OK, take it out in the bright sunshine. If you're not skipping grits, then maybe you're using a cheap sandpaper. The sages say you should use sandpaper like someone else is paying for it. But they are talking about high-class sandpaper. Maybe you're sanding at a speed that's too high. If you haven't read Russ Fairfield's writings on sanding, you're missing out. Then again, you may be doing the best job of sanding in the world, and the wood is crappy! We all dislike sanding, but there can be many reasons that scratches show up!

[Allen Neighbors]

A bright incandescant light, close to the piece with your line of sight at an angle to the surface will usually show everything. The Mineral Spirits or Naptha trick will also help.
When you finish one grit, inspect it, and check out the size of the sanding marks. When you finish the next grit, make sure there are none of the previous grit's marks left over. I reverse the direction of the lathe between grits, and when I get to the final grits, 400/0000 steel wool/brown paper/600 (sometimes), I sand in both directions on these final grits, and sand more than I think is necessary. Then inspect again when finished. Other than lighting being very close to the work, I don't know what the problem could be unless you're getting in a hurry. A wise old fellow who'd been in the furniture building and repair business for about a million years told me one time, the when I'd finished the grit, to sand it a little bit more.

[curtis rosche]

when i sand, i find that if i take a peice of paper backed sand paper, about hand sized, use one half of it for the inside untill the paper starts to really get smooth, then use the other isde and go over the inside again, do the same for the outside with a new peice, i find that for every peice, unless it has epoxy, this gets all of them out pretty good

[Curt Fuller]

Poor lighting is the bigest problem, i have changed my lighting i have a double floresent fitting over my lathe with a natural daylight tubes in it, also for the tubes to work propley you need to have the defuser fitted, i used to go up the house and give it to the wife and ask what she thought and it would be you have some marks, WHAT bad lighting:mad:, change your lighting, if you sand right then its the only other way..we buy good tools and forget the lighting most of the time,, Geoff

I've got to agree that the lighting makes a huge difference. And in my case, taking off face shields, safety glasses, etc and cleaning them usually brings out the flaws in the finish. But I'd guess the lighing is the real reason why they show up once you get them in the house.

[Hilel Salomon]

I find that when I wipe a bowl w/a paper towel doused with alcohol (not single malt scotch but rubbing stuff) I will generally see where I need to either keep sanding or put some wax on and sand w/wet-dry sandpaper. Do I get every scratch? NO WAY. Sometimes I'm lucky though.
Hilel.

[Alan Tolchinsky]

I agree with Allen about a bright incadescent light. I've read that flourescent lighting is really not good for seeing details like sanding marks. I use a 100 watt bulb in a clamp on lighting fixture that I move around the bowl to reveal where I need more sanding. It's like looking for problem areas when sanding fl#t work and using the light at an oblique angle.

[neil mackay]

I agree with Al, sand, then sand some more and go down the grits no matter how tedious.



A bright incandescant light, close to the piece with your line of sight at an angle to the surface will usually show everything.


It aint always the amount but rather the angle of attack
.


When you finish one grit, inspect it, and check out the size of the sanding marks. When you finish the next grit, make sure there are none of the previous grit's marks left over. I reverse the direction of the lathe between grits, and when I get to the final grits, 400/0000 steel wool/brown paper/600 (sometimes), I sand in both directions on these final grits, and sand more than I think is necessary. Then inspect again when finished. Other than lighting being very close to the work, I don't know what the problem could be unless you're getting in a hurry. A wise old fellow who'd been in the furniture building and repair business for about a million years told me one time, the when I'd finished the grit, to sand it a little bit more


Some of the Japanese go down to 2000 then finish off...yep 'finish off' :D
With ash. :)

[Roger Wilson]

Do you vacuum between grits ? It's possible some of the larger particles from a previous grit size are hanging around producing scratches.

[Malcolm Tibbetts]

Because I do a lot of small detailed work (segmented), I have a pair of four-power magnification glasses. If your surface looks good under that kind of scrutiny, then it's likely to look good to anyone's eye's.

[Kaj Petersen]

Hi.

I tried the same one day... with at small bowl. After finnishing af buffing, I took the bowl out to the daylight, and found marks and scratches.

I got interested in the quality of the sand paper, and looked at some of the 240 cheap/crappy sand paper i bought in a local store. Through af magnifying glass, it looked like that a new piece of 240 had "stones/rubble from af 40 or 60 in the surface.

From now on I will buy the good quality sand paper... and pay a little more.

Cheers
Kaj - from the other side of the pond

[Vince Welch]

Hi Jim,

I talk about removing sanding marks on my web site under sanding suggestions. You might find it helpful. You can goggle my name Vince Welch and wood and you should get my website. I do not think I am suppose to list my website on this forum. However, I have given sanding discs to members to try out on this site if that helps you. Hope this helps, Vince