34.) A Free Lunch!

Do you love sanding?

No?  Are you sure?  Want to think it over at little more carefully before you reply?

Okay. Alright. I don't love it either. But it is and probably always will be a critical part of boat work. So that's why this humble boat restorer decided to invest four hours of his day today attending a free seminar focused exclusively on the topic of sanding. It was sponsored by Stiles, a Michigan-based machinery company, hosted by a cabinet shop in Greenpoint, and attended by a representative from 3M.

Overall, the session was kind of disappointing. I learned much more about sanding technique several years ago by spending half an hour with Carl at McMichael's Yacht Yard in Mamaroneck. Carl is a real treasure. He transforms sanding into something approaching an art form. He doesn't use machines or sanding blocks, but instead folds a piece of sandpaper carefully in his palm and goes to work, letting his trained hands feel the highs and lows he needs to even out with the paper. He also feels the resistance of the paper as it scratches the surface, information that tells him how close he is to being able to move to a higher grade. He focuses on one small area at a time and doesn't move on to the next until he has the object of his current focus finished. He does amazing work that I can't duplicate in either speed or quality no matter how hard I try. His level of patience and discipline are superhero qualities to me. I'm patient, too, but if sanding were a sport I'd be on the junior farm team and Carl would be on the starting lineup on a pro team. 

I did learn something at the event that I had never heard before that I think is worth passing on. It's this: As soon as it is freshly sanded, wood that's newly exposed to air begins to oxidize. Within 24 to 48 hours, it's composition is affected and starts to change. This matters because it affects the ability of a finish to penetrate the wood fibers, impacting the appearance of a finish (especially a stain, varnish, sealer—or anything transparent) as well as the adhesion of the coating.

The bottom line: don't let 24 hours elapse between the time you finish sanding something (whether it's a mahogany tiller or a hardwood floor) and the first coat of finish. The 3M guy said that cabinet makers who complain about the results they get in the finishing room often end up revealing that they typically complete construction on Friday and begin the finishing process on Monday. Big mistake.

If in doubt, MMM suggest you try the drip test. Put droplets of water on your sanded wood and see if the droplets disperse and penetrate the wood or if they tend to sit intact on the surface. If the latter happens, the oxidation has become a problem and will lead to things like stain blotches on a beautiful piece of hard maple.

A piece of sandpaper rated 36 is not exactly interchangeable with one rated P36.

Another thing I suspected but didn't know for sure is that a regular 220 grit sandpaper is different from P220 paper. The ratings with the P follow the European numbering system, which has been gaining in popularity. They are not radically different, but they are different. (I don't know if that's because Europeans measure the grain count metrically rather than Imperially. I do know that the ratings for U.S.-made sandpaper relates to the number of tiny pieces of crushed rock glued to the paper per square inch. A 220 paper has 380 fewer pieces of rock on it per square inch than a 600 paper.)  There's also some new measurement system I didn't pay much attention to in which the finest paper is rated 1 and everything courser has a correspondingly higher number.   If you want to see how this confusion plays out, click on this link: http://www.mibnet.se/home-improvement/sandpaper-grit-size-comparison-between-european-and-us-standards.html  It might help you get your ps straight, if not your qs.

The final thing I learned is that 3M has developed a new sandpaper that is somewhat revolutionary (in the sanding world at least). It contains a new abrasive made of a ceramic mineral that has two advantages: first, unlike the particles on regular sandpaper, the abrasive is identically sized and shaped; second, the tiny bits of stuff that scratch gradually break down in a controlled manner forming sharp new peaks that keeps the sandpaper working.

From 3M literature: "The secret lies in the revolutionary precision-shaped ceramic grain technology pioneered by 3M. As the triangular shaped grain 

wears, it continuously fractures to form sharp points and edges that 

slice through metal, wear evenly and provide super-long life and 

consistency at any grinding pressure."

The new sandpaper is made of a ceramic mineral and the new brand is something 3M is calling "Cubritron II."  (I have no idea what happened to the first Cubitron).

"This is already a game changer in the metalworking world," the 3M guy declared—and I think that's probably at least mostly true, mind-blowing as it may be. At the moment, the new paper is available only in very rough grits for wood: 36, 60 and 80. But I plan to try to get my hands on some, try it out, and report on the results. There were no free samples at the sanding seminar (I am still shaking my head that I voluntarily went to such an event). But I did get a free roast beef sandwich.

One reason I didn't learn more at the session was that it covered a lot of stuff I already know.  If you have questions about sandpaper, drop me a line and I'll be happy to help.