Replies

1. 
   hammer1 | Mar 01, 2012 08:55am | #1

   There are a few things to know about sandpaper. There are several types of abrasives on sandpaper, Aluminum oxide is commonly used for wood since the particles are friable, meaning they break and produce fresh sharp particles as you sand. 400 paper is normally silicon carbide which is also friable but wood is not hard enough to do it. Sandpaper comes in closed and open coat. This means there are spaces between the grit so there are places for the waste to go. Your 320 is probably open coat, the 400 is closed coat. As you sand with the fine 400 closed coat, the waste bulds up, the particles don't break down and you are rubbing the surface with junk on the paper creating scratches. This can be overcome to some extent with lots of water but that isn't something you want to do with an oil finish. There really isn't any need to wet sand or sand in oil finishes, it just makes a mess and can cause marks. If you feel the need to sand finer than 320, you should find some open coat paper, not readily available at ordinary suppliers. There is a lot more to sandpaper, backing types, cloth, different weight papers, etc. 3M makes an A weight paper backed open coat in 500 grit which is about as fine as anyone would need in woodworking.

1. 
   iamlearning | Mar 01, 2012 11:07am | #3

   Oil finish advice needed

   Thanks for the comment.  I am using Klingspore papers and those up through 320 grit are open coat.  I was following advice given here:  http://woodworking.com/ww/Article/Super_Smooth_Oil_Finish_7507.aspx  and here  http://www.wwch.org/Technique/Finishes/OilFin.htm  for a technique to fill in the open pores by wet sanding with oil.  I expect your analysis is correct and I got a lot of rubbing with junk.  I may not have used enough oil to maintain a true liquid slurry, but I think I will just sand away my mistake and stick with the open pores.

   So, should I clean up with 320 grit or go back to a lower grit?

   Thanks

2. 
   Westchester | Mar 01, 2012 10:39am | #2

   Streaks

   Figured walnut can absorb a lot of oil - maybe you just need more applications of oil to fill in the streaks -

   SA

1. 
   iamlearning | Mar 01, 2012 11:09am | #4

   oil finish advice needed

   Thanks for your comment.  I did apply another coat with your idea in mind, but it didn't help.  The streaks seem to be due to rubbing with junk that builds up when I wet-sand.  I probably should have used much more oil to avoid that, but I am not inclined to try again.

1. 
   user-64052 | Mar 01, 2012 12:40pm | #5

   one should not

   put oil or any solvent based finish on the inside of a container.  the smell will never leave and will permeate anything that is put in there.

   ron

3. 
   HowardAcheson | Mar 01, 2012 01:21pm | #6

   First, you should understand that Watco is formulated to be an in-the-wood finish leaving the look and feel of the wood.  It contains mostly mineral spirits and linseed oil with a slight amount of varnish.  It will never leave a gloss finish no matter how  you apply it.  It's just not formulated to build a gloss film finish kind of gloss nor will it leave a very durable, long lasting finish.

   Second, sanding the wood to a high sandpaper grit number will tend to burnish the surface is places.  The burnishing causes the oil be be unevenly absorbed.  For walnut I find that sanding to 220 grit by hand is the best.  Don't us a machine for the final sanding as that will tend to burnish the surface also.

   Following the manufacturer's application instructions is the best way to get good results from their finish.  They spend lots of time testing their finish an know what will give you the best results.

   If I recall, the instructions say to apply the finish and keep it wet for 15-20 minutes.  Then wipe off all the excess finish.  Let it dry overnight and do it again.  With the second application, you can sand the finish in using 220 wet&dry paper.  This builds a slurry.  The slurry tends to partially fill the grain and should be wiped fairly gently across the grain or you will end up just wiping it all off.

   Let the item fully dry for 5-7 days before using it.  As said, if you use the Watco on the inside, you will end up with a linseed oil odor every time you open the box.  Anything, particularly cloth items, will be permeated with the odor.  Insides should be coated with shellac, lacquer or waterborne finishes only.

   If you plan to use this type of finish again, let me suggest you mix up your own oil/varnish mixture.  Mix equal parts of your favorite varnish or poly varnish, boiled linseed oil and mineral spirits.  This will give you a better product than Watco which is mostly mineral spirits.  Beause of the higher varnish content, this oil/varnish mixture will give you a more durable and protective finish with the same look as the Watco.

1. 
   iamlearning | Mar 01, 2012 09:26pm | #9

   First you should understand

   Thanks for your very helpful comments Howie.  I wet-sanded because I thought I could fill the grain.  I followed a protocol recommended here http://woodworking.com/ww/Article/Super_Smooth_Oil_Finish_7507.aspx and  here  http://www.wwch.org/Technique/Finishes/OilFin.htm.   I achieved that goal, but paid a price for it.  I probably used poor technique, but all sanding was by hand.  Your point on burnishing is interesting and I will watch out for it.  I believe Doug Stowe uses Watco inside and out.  That's why I did.  Odor will not be a problem with this box, but I sure will check it over time.  The mix your own idea is good and I will use it in future.

4. 
   Paintguru | Mar 01, 2012 08:23pm | #7

   Fine sanding

   I am a paint contractor by trade. I don't like wet sanding bare wood, nor the sandpaper you mentioned . Last year a cabinet maker turned us on to Rhynosoft by Indasa , I use 220 and 320 grit. It is a non clogging paper with foam backing, comes on a roll or about $ 40. A piece of this goes much longer than any sheet paper you buy in the local store. Google it and buy a roll , about $ 45.

1. 
   Paintguru | Mar 01, 2012 08:29pm | #8

   Finish

   Forgot to mention the finish, Keep it simple , try a rub on tongue oil, like one by Zar, lays out smooth, with several coats, you'll think you sprayed it on. Builds a nice gloss too !

2. 
   iamlearning | Mar 01, 2012 09:29pm | #10

   Fine sanding

   Thanks paintguru.  I will follow up on Rhynosoft.  Several folks agree with you about make your own oil.  I plan to do that.

5. 
   iamlearning | Mar 01, 2012 09:51pm | #11

   Oil varnish mixes, ....

   Thanks Steve.  I will try your ideas before I sand.  I will also keep your closing aphorism in mind allways.

1. 
   HowardAcheson | Mar 02, 2012 12:11pm | #12

   According to the ZAR "tung

   According to the ZAR "tung oil" Material Safety Data Sheet, the product contains no real tung oil.  The oil used to make it into a finsih is linseed oil.  In that regard it's similar to Minwax Tung Oil Finish and a number of other faux Tung Oil Finishes. 

6. 
   swannyww | Mar 07, 2012 01:08pm | #13

   oil finish

   I use a grey or white woven or non woven 3m pad to even out the look at the end.  i also use the same pads for application of watco and rub it in with it.  Hood finishing makes a rub out formula that will smooth the final product even more ( kind of like a soapy product used with a white pad.  wet sanding with sandpaper hits the high spots but can't reach the valleys therefore it looks uneven.

7. 
   iamlearning | Mar 07, 2012 01:54pm | #14

   How to correct mistake

   Thanks for your tip.  I haven't used the 3M pads, but I need to check them out.