# Sanding plywood to stain



## redcoatd (Mar 25, 2014)

Hi,

I'm a relative newbie...

I purchased some stain-grade plywood from Lowes, with one nice sanded side, and the other dull. I used it to redo an aquarium stand, and I have now started prepping it for staining.

I'm using a palm sander, and started with course sandpaper, progressing to medium (and then I'll use fine etc).

However, when inspecting the plywood, it's still not fully smooth - there are still some indentations in it. Wondering if I should go back to the course sandpaper until it's perfectly smooth? Or will this kind of plywood never be perfectly smooth?

All advice appreciated!

thanks!


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## Steve Neul (Sep 2, 2011)

To really give you an answer I would need to know what kind of wood the plywood was veneered with, what kind of palm sander you have and what grits sandpaper you used. 

You have to be careful doing very much sanding on today's plywood. Often there isn't enough veneer to do that. Some plywood has such hard and soft places you can make the wood rougher with some palm sanders because they tend to sand the soft parts of the wood rather than sanding flat.


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## redcoatd (Mar 25, 2014)

Hi,

Forgot to mention those details:

- pine plywood
- Makita Finishing sander B04550
- used course (80 grit) and then medium (120)

Trying to upload some closeups...I sanded the front only a little, the side somewhat more.

thanks!


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## cabinetman (Jul 5, 2007)

We have an introduction section where you can say a few words about yourself. If you fill out your profile in your "User Control Panel", you can list any hobbies, experience or other facts. You can also list your general geographical location which would be a help in answering some questions. In doing that your location will show under your username when you post. 

Using pine plywood, it's likely you'll not get it flat. Construction grade faces will vary in thickness, and will be mostly rotary cut veneers. Using 80x to start is way too coarse. If you have to use plywood at all, and start with a hardwood face, start with 180x-220x just for a light clean up. The faces are very thin, and you can perforate the veneer very easy.












 








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## Steve Neul (Sep 2, 2011)

The plywood you are using will be very difficult if not impossible to sand to a stain finish. You certainly won't sand the defects out with the sander you are using. It is a finish sander which is intended to be used with the most finest grits paper. It is also the type sander I mentioned in post 2 that would eat away the soft parts of the wood giving the wood a washboard texture to it. For that type sanding a random orbital sander is a better choice. It has a harder pad on the bottom of it that will keep the sanding flat. Anyway look at the plywood on the edge and see how thick the outer veneer is before attempting to do that much sanding. You would probably need to sand a 1/32" off that side of the plywood to smooth those spots. There is no reason you can't use 80 grit sandpaper to do your initial sanding however you have to understand the sander will scratch the wood in swirl marks so it takes a thorough sanding with the 120 grit to remove the damage the 80 grit makes. Then it should be sanded again with 180 grit and with that wood finish with 220 grit. It also helps when going to a finer grit you wet the wood raising the grain. What I would suggest is using a pastewood grain filler. It's kind of like a wood putty that is thin enough to brush on. You need to try some stain on a piece of scrap first to see what color the filler needs to be. Sherwin Williams makes a grain filler which comes in a natural color but they can tint it for you. You might take a sample of the stained wood for them to make it for you. You thin it to about the consistency of mayonnaise and brush the filler on in a area about 3' square at a time and let it thicken to a heavy paste. Then with a squeegee like you clean a car windshield, squeegee as much of the grain filler off. If there is places like moldings or places you can't get to with the squeegee you can rub it into the grain with a rag rubbing it across the grain as much as possible. After the filler dries overnight there may be places where there is a haze. This should be sanded off with a light sanding. Then the wood is ready to finish. The plywood you are using will be prone to blotching so you might use a wood conditioner prior to staining. This will allow the stain to go on more uniform. Another option would be to use a gel stain. Much of the pigment on that type stain is on the surface and would obscure the wood. Once stained a clear coating can be finished over it. Be sure you try the finish all the way to the clear coat to see if you like it before putting anything on your project.


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## del schisler (Nov 5, 2009)

redcoatd said:


> Hi,
> 
> I'm a relative newbie...
> 
> ...


look's like you have sanded thro the top ply, also ply wood is the hardest to stain , you will have so much blotching in my opion it will look bad . i would use some other wood . watch this video on staining and you will see what i mean,


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## redcoatd (Mar 25, 2014)

Hmmmm - I guess that's why I'm a newbie 

I don't think I've sanded through the top ply - I haven't sanded that much at all. Those pics were very close up.

The pastewood grain filler sounds like a lot of work...would it really give me a good finish?

Or am I better off just sanding it with finer grit and stain/varnish? Any thoughts on what kind of finish that would give me?

I went with plywood as I'm adding trim pieces that I wanted to look the same. Sigh.


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## mako1 (Jan 25, 2014)

There is no problem using plywood.That is what is used in most cabinets build today.The problem is that you are using construction grade in place of cabinet grade plywood.You would have been better off using something like a birch veneer cabinet grade ply.Also available at the big box store though usually in a BC grade.


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## Steve Neul (Sep 2, 2011)

redcoatd said:


> Hmmmm - I guess that's why I'm a newbie
> 
> I don't think I've sanded through the top ply - I haven't sanded that much at all. Those pics were very close up.
> 
> ...


The grain filler is additional work but not nearly as much work as trying to sand the wood smooth. It is what grain filler is made for. Woods like oak, mahogany and walnut have a texture to the wood you can see in the finish. For those that don't want to see the texture a grain filler is used. There is no reason the same procedure couldn't be used on rough pine.


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## Bleedinblue (Mar 4, 2014)

I used grain filler for the first time a few weeks ago. It's messy, but straight forward. I used it on oak ply and it turned out pretty good. I don't think I'll stain plywood without it again. Give it a shot.


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## cabinetman (Jul 5, 2007)

Grain filler fills grain and pores. It does not fill deviations in rotary cut veneer face grain.








 







.


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## redcoatd (Mar 25, 2014)

Hmmm...so now I'm really confused as to whether it'll help me or not!


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## Steve Neul (Sep 2, 2011)

redcoatd said:


> Hmmm...so now I'm really confused as to whether it'll help me or not!


Don't be confused. It works because I've used it for exactly that application.


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## redcoatd (Mar 25, 2014)

Steve Neul said:


> Don't be confused. It works because I've used it for exactly that application.


Ok, great.

Which type did you use? Did you color beforehand? I've seen some clear ones advertised - could I use that?

And I'm a little confused whether you apply it after you stain or before? How many coats did it take to cover the indentations?

cheers

David


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## Steve Neul (Sep 2, 2011)

redcoatd said:


> Ok, great.
> 
> Which type did you use? Did you color beforehand? I've seen some clear ones advertised - could I use that?
> 
> ...


The clear ones like crystalac work better for filling grain. Where you have larger places to fill a pigmented oil base grain filler would do better. The paint store can tint it to match any color you want. http://www.paintdocs.com/webmsds/webPDF.jsp?SITEID=STORECAT&prodno=CC-F12&doctype=PDS&lang=E


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## redcoatd (Mar 25, 2014)

Thanks...

Still confused about whether to apply before or after stain?

Or is that the finish itself, and I just apply that?


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## Steve Neul (Sep 2, 2011)

redcoatd said:


> Thanks...
> 
> Still confused about whether to apply before or after stain?
> 
> Or is that the finish itself, and I just apply that?


Sometimes if you get the color right you can fill the wood and stain it in one application. Then a light sanding and all that is needed is the clear finish over it. If the color still isn't right you can stain the wood after the filler. The problem in this case though is the wood is prone to blotch so you probably should use a wood conditioner first. Just be sure to practice on scrap wood.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> Don't be confused. It works because I've used it for exactly that application.





Steve Neul said:


> Sometimes if you get the color right you can fill the wood and stain it in one application. Then a light sanding and all that is needed is the clear finish over it. If the color still isn't right you can stain the wood after the filler. The problem in this case though is the wood is prone to blotch so you probably should use a wood conditioner first. Just be sure to practice on scrap wood.


So, if you're saying that grain filler will level out all the highs and lows on the face of rotary cut veneer plywood, like pine or fir, make up a small sample to show. It doesn't have to be a 4'x8' sheet, just a small scrap that you have laying around the shop.

Just note that to level out the surface to look like glass, that besides the grain filler, and the simple clear finish you mentioned, that it doesn't take numerous top coats, wet block sanded to get that finish that levels out all the deviations.








 







.


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## GeorgeC (Jul 30, 2008)

Steve Neul said:


> The plywood you are using will be very difficult if not impossible to sand to a stain finish. You certainly won't sand the defects out with the sander you are using. It is a finish sander which is intended to be used with the most finest grits paper. It is also the type sander I mentioned in post 2 that would eat away the soft parts of the wood giving the wood a washboard texture to it. For that type sanding a random orbital sander is a better choice. It has a harder pad on the bottom of it that will keep the sanding flat. Anyway look at the plywood on the edge and see how thick the outer veneer is before attempting to do that much sanding. You would probably need to sand a 1/32" off that side of the plywood to smooth those spots. There is no reason you can't use 80 grit sandpaper to do your initial sanding however you have to understand the sander will scratch the wood in swirl marks so it takes a thorough sanding with the 120 grit to remove the damage the 80 grit makes. Then it should be sanded again with 180 grit and with that wood finish with 220 grit. It also helps when going to a finer grit you wet the wood raising the grain. What I would suggest is using a pastewood grain filler. It's kind of like a wood putty that is thin enough to brush on. You need to try some stain on a piece of scrap first to see what color the filler needs to be. Sherwin Williams makes a grain filler which comes in a natural color but they can tint it for you. You might take a sample of the stained wood for them to make it for you. You thin it to about the consistency of mayonnaise and brush the filler on in a area about 3' square at a time and let it thicken to a heavy paste. Then with a squeegee like you clean a car windshield, squeegee as much of the grain filler off. If there is places like moldings or places you can't get to with the squeegee you can rub it into the grain with a rag rubbing it across the grain as much as possible. After the filler dries overnight there may be places where there is a haze. This should be sanded off with a light sanding. Then the wood is ready to finish. The plywood you are using will be prone to blotching so you might use a wood conditioner prior to staining. This will allow the stain to go on more uniform. Another option would be to use a gel stain. Much of the pigment on that type stain is on the surface and would obscure the wood. Once stained a clear coating can be finished over it. Be sure you try the finish all the way to the clear coat to see if you like it before putting anything on your project.


WOW! Now that is a record paragraph.

George


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## Steve Neul (Sep 2, 2011)

cabinetman said:


> So, if you're saying that grain filler will level out all the highs and lows on the face of rotary cut veneer plywood, like pine or fir, make up a small sample to show. It doesn't have to be a 4'x8' sheet, just a small scrap that you have laying around the shop.
> 
> Just note that to level out the surface to look like glass, that besides the grain filler, and the simple clear finish you mentioned, that it doesn't take numerous top coats, wet block sanded to get that finish that levels out all the deviations.
> 
> ...


I don't understand why you are confused. A grain filler can easily fill tear out spots like this. The recomendation for the small piece of scrap is to work out the color for the wood filler in order to get a color that isn't too dark or too light. Yes, depending on the type of finish the op wants to bring the finish to a glass like finish it would take multiple coats however the term glass like finish pretained to those finishing walnut or mahogany. I doubt if the OP has any intention of going that far on pine. He just doesn't want the tear out on the plywood.


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## cabinetman (Jul 5, 2007)

Steve Neul said:


> I don't understand why you are confused. A grain filler can easily fill tear out spots like this.


Confused...I'm not confused. With all due respect, you are evading and avoiding the issue of how flat rotary grain plywood is. Those little tear outs will get filled with grain filler. But grain filler will not even out the waviness of grain differential. To be specific, flattening out the mountains and the valleys. It would take many coats of topcoat to fill in the lows, and sanding off the highs to get an even playing field.

In the OP's words...

_"I'm using a palm sander, and started with course sandpaper, progressing to medium (and then I'll use fine etc).

However, when inspecting the plywood, it's still not *fully smooth* - there are still some *indentations* in it. Wondering if I should go back to the course sandpaper until it's *perfectly smooth*? Or will this kind of plywood never be perfectly smooth?_"









 







.


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## Steve Neul (Sep 2, 2011)

cabinetman said:


> Confused...I'm not confused. With all due respect, you are evading and avoiding the issue of how flat rotary grain plywood is. Those little tear outs will get filled with grain filler. But grain filler will not even out the waviness of grain differential. To be specific, flattening out the mountains and the valleys. It would take many coats of topcoat to fill in the lows, and sanding off the highs to get an even playing field.
> 
> In the OP's words...
> 
> ...


Your just trying to change the parameters of what the OP is doing. He's just concerned with the tear out, not the overall levelness of the sheet.


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