Wood preparation for finishing

[Ron Hitchcock]

I'm taking a class in wood finishing. Panels (6" x 12") of red oak and walnut are prepared, one side has been planed (planar/jointer) and the side went thru the drum sander (120 grit) As an example each side is sanded to 600 grit, going thru all the grits, then it's dampened to raise the grain.

Question: Why does the side that went thru the drum sander require more sanding to remove the raised grain. The planed side dampen twice and sand in between. The other side requires several dampen/sanding cycles to eliminated raised grain.

[Keith Strong]

I just had this same issue, I would love to know the answer too. It was QSWO, unfortunately the drum sanded material took stain a little different. Also as Ron mentioned grain raising was terrible.

[John TenEyck]

I had the same problem with rift sawn WO after 120 grit though my drum sander followed by 120, 150, 180 grit with the ROS, followed by 180 grit by hand. The grain raised up like porcupine quills. I modified the process as follows: 120 grit drum sander followed by 100, 150, 180, 220 grit with the ROS, followed by 320 grit by hand. No more problems. One or two wipes with water and de-whiskering and I'm ready to dye. I think starting with the 100 grit in the ROS was the most important step.

John

[Prashun Patel]

I know that hand planed wood does not seem to get raised grain when dampened as does wood sanded with my ROS.

I think it has to do with how the wood fibers are severed. The jointing/planing process cuts them instead of abrading and grinding them off. I always thought that grinding process creates 'fluffier' ends that are more prone to absorbing water and therefore swelling the wood fibers. I wonder if the drum sander sands so aggressively that it's really opening the ends up to water even more than a ROS does. So, it's not just the grit, but the aggressiveness with which the grit is applied that matters. This is all just hypothesis.

[Kent A Bathurst]

Maybe I'm nuts, but.....

QSWO - I used to do the grain-raising deal. Then I stopped - sort of:

First thing on the wood is a couple light coats of 1# shellac. Then, a light scuff sanding. Then, WB Transfast dye, then shellac seal coat again, with scuff sanding.

There ain't no fuzzies left by then.

Am I missing something?

[Ron Hitchcock]

I will sneak a card scraper into class to save on the elbow grease. Thanks for your opinions and expertise.