# Steps for sanding poplar prior to painting



## Goldglv (Jun 24, 2009)

I am building a toy box for my daughter. I'm using poplar for a face frame. How should I go about sanding it? Plan on using latex paint. 

I've read using 80 then 150 then 220 prior to priming. I've also read people using up to 400. 

Can anyone advise on what grits I should use to get a nice finish?

Thanks!


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## cabinetman (Jul 5, 2007)

Goldglv said:


> I am building a toy box for my daughter. I'm using poplar for a face frame. How should I go about sanding it? Plan on using latex paint.
> 
> I've read using 80 then 150 then 220 prior to priming. I've also read people using up to 400.
> 
> ...


I wouldn't use 80x at all. You could start with 100x-120x-150 and finish off at 180x-220x-280x. What paint regimen are you planning...type of paint, and the method of application.










 







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## mdntrdr (Dec 22, 2009)

I would sand to 120x.

Then sand your primer/paint coats with 320x. 

Your final finish will only be as smooth as you can apply unless you sand and polish it back. 

What method of application are you planning? :smile:


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## Goldglv (Jun 24, 2009)

Was planning on 2 coats of zinsser 123 and 2 coats of latex paint using a roller. Want to stay away from anything oil based because of the fumes. 

Toybox was built with 3/4 birch ply. 

Any suggestions?


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## chemmy (Dec 13, 2011)

Goldglv said:


> Was planning on 2 coats of zinsser 123 and 2 coats of latex paint using a roller. Want to stay away from anything oil based because of the fumes.
> 
> Toybox was built with 3/4 birch ply.
> 
> Any suggestions?


150 is good enough for the wood, sand the primer with 220 - 320, apply your latex. Best results will be with a short nap [1/4"] roller:yes:


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## HowardAcheson (Nov 25, 2011)

Here is some info on surface preparation that may be helpful.

Sanding wood--hard or soft--beyond 220 does little more than burnish the wood making staining difficult. This is particularly true if you are using a pigment stain which sits on the surface and relies on "nooks and crannies" to impart color. Softer more porous woods can be sanded to to 220 but harder less absorbent woods may stain best if only sanded to 150. The best compromise is to aim for 180 grit. 

A number of years ago a large cabinet/custom furniture shop I was involved with did series of adhesion tests with various finishes and sealers. As part of this test we explored adhesion based on sanding grit. We found about the same adhesion up to 180 - 220. Beyond 220 adhesion dropped off due to burnishing of the underlying wood particularly when non-linear machine sanders were used. This was tested on birch panels. We also found that the resulting smoothness of the first coat of finish was not materially affected by the smoothnes of the underlying wood for sandpaper grits between 150 - 220.. The smoothest surface substrate for final finishes was obtained by sanding lightly after the first coat of finish was applied and dry. Which makes the case for a thinned first coat of finish.

So our conclusion was that sanding beyond 180-220 was not necessary and could be actually detrimental. 

But, most important was that there was a big appearance affect if the surface was not HAND sanded in the direction of the grain using the highest grit used on the sanding machine. A flat pad sander produced a much flatter surface than a ROS. However, both required final hand sanding with the grain for optimum appearence. If not hand sanded, swirl scratches could show. Final hand sanding using a sanding pad in the direction of the grain is a must. 

To carry it one step further, sanding at 320-400 grit after the first coat and subsequent coats was the optimum. No improved appearence was noticed by between coat sanding beyond 400 for varnish. 400 was the sweet spot for thinner finishes. Between coat sanding was always done by hand whether for flattening or for adhesion. 

I think you will find similar thoughts in the popular finishing books but YMMV.

Finally, the first coat of ANY finish will soak little shards of wood and cause them to raise whether the surface was sanded, planed or scraped. When the first coat of finish dries these hardened shards are what causes the surface to feel rough. Sanding with 320 paper will remove these hardened shards and subsequent coats will go on smoother. So, smoothness counts after the first coat of finish, but not much before that.

The finish left by the sizing machine determines the starting grit. Jointers, planers, belt sanders etc, should leave a finish that allows starting with 100 grit. From there, go to 120 grit and sand until the marks from the prior grit are gone, then move to 150 and finish at 180 grit.

Plywood is factory sanded to 180 grit. Therefore, it's best to not sand plywood except with 180 grit and sand by hand. Get the first coat of finish on and then sand with 320. That way you are sanding the finish, not the wood. This avoids sanding through today's very thin surface veneer.


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