Sanding

[Garno]

Please bare in mind I am an absolute novice. (homer)

When sanding down wood why do we need to do it in stages? 40 grit, 80 grit, 120 grit, 180 grit, 240 grit.
Why can't we just use the 240 grit?

Also do the same rules apply to someone who does woodwork as a hobby and a professional woodworker?

Gary

 

[thick_mike]

When you are sanding you want to remove surface imperfections and then smooth. The lower grits remove material quickly, but leave a rough surface, the higher grits remove material less quickly, but leave a smoother surface. If your piece doesn’t have lumps and bumps, then you can ignore the coarser grits and just tickle them with 240.

 

[Garno]

Thank you Mike

 

[Brandlin]

Sanding is basically scratching.

Each grade replaces larger scratches with smaller ones ... and so on. It isn't necessary to use every grit or even to start with the most aggressive (unless you have an especially rough starting surface) but if you take a rough piece of wood and attack it with a high grit you'll be there forever with your tiny scratches trying to remove the great big peaks on the rough surface.

This approach to sanding in stages becomes even more apparent when you get to certain finishes when you can be sanding between varnish coats with 600 grit or higher...

 

[Tasky]

Why can't we just use the 240 grit?

You can if you want.... might take a while, though! :lol:

Also do the same rules apply to someone who does woodwork as a hobby and a professional woodworker?

"The only rules that really matter are these: what a man can do and what a man cannot do".
So beyond breaking the laws of physics, that govern how sandpapering works, you can do whatever you like. So long as you're having fun and not hurting anyone, it's all good and there are no further rules.

 

[Garno]

Thank you Brandlin and Tasky

 

[thetyreman]

that's what smoothing planes are for, plane over the final surface with a no4 or 4 1/2, then sand at 240 grit, you will save a lot of time and money, I'd always rather plane it first with an incredibly sharp plane than start at a lower grit.

 

[Garno]

that's what smoothing planes are for, plane over the final surface with a no4 or 4 1/2, then sand at 240 grit, you will save a lot of time and money, I'd always rather plane it first with an incredibly sharp plane than start at a lower grit.

I do like that idea

 

[Silly_Billy]

To be honest, after using my No. 4 smoothing plane, I often wonder if I need to sand at all. Do you think sanding is always necessary? Is sanding important for some wood finishes to adhere to the wood?

 

[thetyreman]

To be honest, after using my No. 4 smoothing plane, I often wonder if I need to sand at all. Do you think sanding is always necessary? Is sanding important for some wood finishes to adhere to the wood?

I get the same feeling, the surface literally looks and feels as close to perfect as possible with a smoothing plane, but sanding does improve how the finish absorbs into the wood, it's worth doing some tests.

 

[CHJ]

......I get the same feeling, the surface literally looks and feels as close to perfect as possible with a smoothing plane, but sanding does improve how the finish absorbs into the wood, it's worth doing some tests.

Is it a case of the sanding actually abrading a smooth (polished?) surface, albeit very fine abrasions, that improves the bond of the finish?