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Tegmark
8th December 2013, 09:02 PM
I read stop at 220grit or else the stain wont grab. But wouldn't you still see the scratches from when the stain fills them up? I mean some stop at 150. That just seems so course by hand. I would have thought 320-400 would be the ballpark minimum. As i can see the lines of 320 scratches on the bare wood with my eye.Also, If I was to buy some pine or hardwood new, do I need to sand before staining? I would like to assume it's good enough to go straight to staining.

fineboxes
9th December 2013, 07:39 AM
Depending on the timber, but as a rule I would say you will still see the scratches.

I go to as you say 320, 400.

If you want a top finish when you've got as far a 400 wet the job down with a good slosh of water, rub it over the job then when its dry sand again starting at 240 though to 400.

This raises the grain which will otherwise raise when you apply the wet stain.
And then (STILL) have to be rubbed back, thus weakening the stain colour causing in some cases blotching:o

On some jobs I have done the wetting stage 2 or 3 times before applying colour of shellac.

BUT ONLY ON SOLID timber DON'T TRY IT ON MDF or Chipboard!!!!!!!!:no:


Cheers

Steve

jimbur
9th December 2013, 05:39 PM
Buying timber new that has been machine-planed will usually have bands of compression across its length. As Steve advises, wetting the timber will allow the compressed areas to lift and then you can really finish the surface.
Make sure it's dry before applying the finish. Not many finishes can cope with moisture under them.

Trav
9th December 2013, 07:01 PM
Until recently I've used water in exactly this way. I've now switched to sanding sealer, which seems (in my view) to work better, as long as you allow enough time for it to properly dry.

Trav

Arron
9th December 2013, 09:23 PM
I read stop at 220grit or else the stain wont grab.
I think that is usually said about the finish (lacquer, varnish etc) not stain, and I don't think it applies anyway.



But wouldn't you still see the scratches from when the stain fills them up?
Yes, though it depends on the timber, what you are sanding with and whether you are sanding across the grain or strictly along the grain. Also whether you are sanding with an orbital, a random orbital or by hand. Orbital sanders leave nasty corkscrew shaped scratches, good ros's don't scratch much at all. Drum sanders and linishers are usually used to sand along the grain - and the eye plays tricks and makes longgrain scratches hard to detect.



I mean some stop at 150. That just seems so course by hand.
I think that's a reference to sanding using a drum sander or linisher. A lot of production-oriented cabinet shops stop at 180 if using a drum sander and clear coating. They will usually be applying a sealer, then sanding again, then applying a fairly high-build laquer or 2pack - with the stain in the finish rather then applied beforehand.



I would have thought 320-400 would be the ballpark minimum. As i can see the lines of 320 scratches on the bare wood with my eye.
I doubt you can see long grain scratches at 320. I think sanding technique could be the problem here. Generally, avoid sanding across grain.

The spec sheets of most spray finishes mention sanding to 180 or 240 and not finer, but you can still get a mirror finish with them. Of course stain is different, and will highlight a scratch which a finish will fill.



Also, If I was to buy some pine or hardwood new, do I need to sand before staining? I would like to assume it's good enough to go straight to staining.
I would expect to sand it. There will be numerous scratches left by the industrial-scale milling machinery and poor handling.


I should also clarify that you wont want to be using a sanding sealer if you are applying a stain before finishing.

cheers
Arron

rrich
10th December 2013, 03:09 PM
If you are using a random orbit sander the trick is to GO SLOWLY. Move the sander constantly but at the rate of about 25MM per second.

AND

After you've sanded with the ROS, go over the project with the same grit on a sanding block and with the grain.

For most stain and oil finishes 220 is about as fine as you want to go. (Better if you stop at 180.)