Replies

1. 
   charlesstanford | Apr 11, 2002 03:46am | #1

   It doesn't really matter now that we have toothpaste.

1. 
   Yale04 | Apr 11, 2002 04:17am | #2

   Toothpaste??

2. 
   HowardAcheson | Apr 11, 2002 04:52am | #3

   Sanding wood--hard or soft--beyond 220 does nothing more than burnish the wood making staining difficult. This is particularly true if you are using a pigment stain which sits on the surface and relies on "nooks and crannies" to impart color.

   A number of years ago a shop I was involved with did series of adhesion tests with various finishes and sealers. As part of this test we explored adhesion based on sanding grit. We found about the same adhesion up to 180 - 220. Beyond 220 adhesion dropped off due to burnishing of the underlying wood. This was tested on birch panels. We also found that the resulting smoothness of the first coat of finish was not materially affected by the smoothnes of the underlying wood, when varnish was used, for sandpaper grits between 150 - 220.. Thin finishes such as lacquer could be affected by grits less than 180.

   So our conclusion was that sanding beyond 180-220 was a waste of time. But, there was a big appearance affect of 180 if it was not hand sanded in the direction of the grain. A ROS at 180 required final hand sanding with the grain for optimum appearence. If not hand sanded, scratches would show. Final hand sanding in the direction of the grain is a must.

   To carry it one step further, sanding at 320 grit after the first coat and subsequent coats was the optimum. Any finer and adhesion problems were encountered. No improved appearence was noticed by between coat sanding beyond 320 for varnish. 400 was the sweet spot for thinner finishes.

   I think you will find similar thoughts in the popular finishing books but YMMV.

3. 
   sschefer | Apr 12, 2002 09:18am | #4

   Interesting Dave.. I was brought up to think that the more you sanded the better the finish would turn out. I never went beyond 220 but I sure spent a lot of time getting there. My old wood shop teacher would turn over in his grave if he read this thread. Then again, maybe thats why I never turn out any quality work...Go figure.

   Steve - in Northern California

1. 
   SCFrankland | Apr 12, 2002 03:50pm | #5

   I have some sand paper here that goes from 3200, 4000, 6000, 8000 and 12000 grit. It is used to polish out finishes and to resurface windows on aircraft. The paper itself is cloth backed and the surface has a leather like feel to it. Scott C. Frankland

   Newfoundland Wood Worker

1. 
   DaveArbuckle | Apr 12, 2002 11:18pm | #6

   Scott, that must be Micro-Mesh you have. Their grits numbers don't correspond to sandpaper grit numbers, though. They have a conversion chart on their web site, http://micro-surface.com/ . Choose Products, then Wood.

   Great stuff for rubbing out a finish.

   Dave

1. 
   SCFrankland | Apr 13, 2002 12:40am | #7

   Ya that's the stuff I have. It has the grit marked on the back just like sand paper. I use it on metal parts that have some minor scuffs and scratches on them. I have also used it to buff out the finish on a few small pieces.Scott C. Frankland

   Newfoundland Wood Worker

4. 
   kaelyn8 | Apr 14, 2002 09:25pm | #8

   This honestly depends on what wood you're using, and what you're making. I do a lot of 4' round tables using cabinet grade 3/4 oak or maple plywood for display tables at renaissance faires. I need them to be pretty much weather proof, so I use polyurethane. If I use 180 grit, the grain raises so much with the first coat of poly that it's half gone by the time I sand it smooth. I start with 180, go to 220, and finish w/300. Between poly coats I use 400. I use 2 coats, and I've used and truly abused these tables for 5 years now. In and out of the truck, no special padding at all. It's finally time to refinish, and I'm just going to sand down a bit w/220, finish @ 300, and recoat. I'm not doing fine furniture here, so I can't make a recommendation about that. Do yourself a favor, wear a mask.

   I have seen some incredible wood boxes finished to 2000 grit, finished with what the guy described as a very light wax, and I'm in love. The zebra and curly maple practicaly glowed, the darker woods like walnut had beautiful depth without the "layer" effect of a polyurethane. If I ever take to that type of work that's probably what I'll do.

   Kay