Replies

1. 
   tufenhundel | Aug 15, 2003 06:55am | #1

   Mulch:

   If I understand you correctly, the ROS surface is smoother than the hand sanded one.  I am going be bold as to guess that the sandpaper you used was aluminum oxide, and the hand sanding was done with a fresh piece of paper.

   I know conventional wisdom says hand sand the last grit, but I always step through each grit on my ROS, and finish on a palm sized finish sander, always using garnet, for the last grit.  This is important because the garnet will dull and allow me to burnish the surface for a nice sheen.

   If I don't skip any grit sizes, and finish carefully with a garnet paper, I have no problems with swirlies.

2. 
   RANGERP75R | Aug 15, 2003 08:05am | #2

   Mulch

       "The piece I didn't hand-sand feels smoother an I didn't detect any swirl marks even after wiping both with naptha".

       If that is true, looks to me as if you've answered your own question... If you don't detect swirl marks with naptha, why go any farther...?

   Good luck...

   sarge..jt

3. 
   RMillard | Aug 15, 2003 02:09pm | #3

   Like you, I will avoid hand sanding at nearly any cost, other than at the expense of the surface quality.

   Since I hand plane all flat solid wood, I rarely have to sand these surfaces. Many of my pieces are veneered , which can ‘t easily be planed, so I am forced to sand more than I’d like. I never use anything more coarse than 180, and then sand with 220 and finish with 320 all using the RO sander. I also hit the planed surfaces with the 320 just prior to finishing to remove handling marks. I dye my work, which not only highlights the grain, but any surface imperfection, like swirl marks, and I have not had any problems with these showing up. The only time I hand sand is after raising the grain. People who use pigmented stains may not want to sand to 320 since it can burnish the wood and affect the way the stain “takes”. In that case, I would probably resort to hand sanding with 220, after using 180 in the RO. This is just conjecture on my part, since I haven’t stained a piece in years, and when I did I will still using a standard orbital sander , which were notorious for leaving swirl marks.

                                           Rob Millard

4. 
   ChasStanford | Aug 15, 2003 02:17pm | #4

   You goal is as much clarity of grain as you can achieve; if you progressed through the grits properly, 'smoothness' is pretty much a given.

   I agree with the statement about garnet sandpaper.   See if hand sanding with garnet gives you noticeably clearer grain, if not then it sounds like the machine has done a fine job for you.  Move on and know that you don't have to hand sand anymore (at least on broad surfaces).

   
   

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   Edited 8/15/2003 3:20:37 PM ET by CHASSTANFORD

5. 
   forestgirl | Aug 15, 2003 07:33pm | #5

   Mulch, the old adage about hand-sanding the last pass is probably left over from the days when random-orbit sanders weren't as well-designed as they are now.  You are using the cat's meow of US sanders, and if it's producing a baby-bottom finish, why fight it?  (I'm on your side about the hand sanding).  Do you have any stock left over that you can experiment with?  That's definitely what I'd do before committing on the real thing.

   forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl   ;-)

   
   

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   Edited 8/15/2003 12:37:09 PM ET by forestgirl

6. 
   HowardAcheson | Aug 15, 2003 11:37pm | #6

   I gave you a detailed answer on WoodCentral but let me add that ROS frequently burnishes the wood particularly if the paper has been well used. If the wood that was machine sanded feels "smoother" than the areas that were hand sanded, I would suspect burnishing. Burnishing causes uneven absorbsion of stains and reduced adhesion of finishes.

   Super smoothness does not equat to a smooth finish. The key to a smooth finish to to flat sand--again by hand--after the initial seal coat.

   You should always hand sand in the direction of the grain as the final step. In the shop I was involved with, this was considered the most important step to good finishing. Generally, the finisher or his assistant/apprentise would give it a final hand sanding.

   Remember, it is the finish that gets the ohh's and ahh's, not the joinery.

   
   

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   Edited 8/15/2003 4:46:27 PM ET by Howie

1. 
   ChasStanford | Aug 16, 2003 01:28am | #7

   Good information.  Quality joinery usually does not get noticed, but bad joinery can ruin the impression afforded by the most exquisite of finish jobs.