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Sanding: how much is too much?

tuanj's picture

I'm guilty of oversanding but am not sure in what way to modify this behavior so that I continue to get good results without neglecting things I shouldn't be...

The best way to help me out is to tell you I'm primarily dealing with softer woods-pine, poplar. I occasionally use oak, maple and ash though for painting purposes (90% of the sanding/painting ) it's mostly poplar.

I sand both sides of everything before priming and two coat with finish paint, four coats or more for varnish. For most things, I'm using 120 grit and then hand-sanding with 220. After priming, I'll use the 220 again before the finish goes on. Ditto for between varnish coats-though I'm switching to a finer grit for surfaces that won't be dangerous underfoot.

Some people say, with flooring anyway, "work through all the grits" but this is surely unnecessary for most applications. What should I be doing with baseboard and other such trim? I do understand that professional carpenter/painters would buy primed wood but working on my house, I buy unfinished and proceed to sand everything first. 

A painting friend of mine once said that both sides of a piece of lumber should be painted and I've done that ever since, including prepping with light sanding on the backside. I'm guessing this might only apply to exterior pieces? And that I might be able to get away with only sanding the exposed lumber for interiors? 

Any pointers are most welcome.

Also the fact that I need a bench sander is painfully obvious to me at this point-as it would take care of 90 % of my work-so would love some recommendations in that department.


When you can see light (post #216419, reply #1 of 5)

When you can see light through the board you've sanded too much.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

I deserved that. Guilty. (post #216419, reply #2 of 5)

I deserved that. Guilty.

Priming the back of your (post #216419, reply #3 of 5)

Priming the back of your boards is really a very good practice that not many people do, as it adds a lot of work to any project. Doing so helps to stabilize the wood from humidity changes and can prevent swelling and shrinkage. 

I am a big fan of the Porter Cable DA (Dual Action) Sander it makes any type of sanding from rough 60grit to fine 220 grit very easy.

Thank you. So I feel somewhat (post #216419, reply #4 of 5)

Thank you. So I feel somewhat redeemed. And especially if it is not a time-sensitive project (ie, pieces can be worked on in advance of installation), sounds worth it to completely prime the wood, interior or exterior.

For ordinary lumber, what grits are you using to take the glaze off? I have been getting by in most cases with a quick pass at 120 and then sanding down the knap that gets raised (with priming) with 220, by hand very quickly. 

When I glue up, I'm often forced to use a belt sander on the joints, usually 80 grit but then it takes a bit of doing to get it smooth from there. Guess I could add a second pass with the belt sander at 100 before the final pass with the palm at 120.

I may be obsessing but it would be good to know what a minimum treatment is.



hmmmm... (post #216419, reply #5 of 5)

This will sound like hack work but I use mostly 80 gr. followed by 100 gr.on most  jobs, even cabinet doors and such. Maybe to 120.

That is done

with my ancient 1/2 sheet milwaukee pad sander which seems to somehow provide magic results. Typically garnet paper to now.

If no stain or rework is involved next step is a sanding  sealer. Once that dries it is hand scuff sanded with open coated lubricated 120 - 240 grit  aluminum oxide paper, it depends on

how the job is going. Between  the next coats  hand scuff sanding will be 180- 220, also open coat lubricated AO paper. 

I don't know what you are calling a bench sander but if it if you mean a stationary machine don't expect that to help you out much.

These remarks are about stain/varnish work not paint..  I rarely worry  about coating 2 sides for interior stuff.