# sanding sealer questions



## MJP (Nov 4, 2010)

I'm starting a new project with red oak. I am using Miniwax sanding sealer on the bare oak. How many coats of sealer should be applied to the wood? So far I have applied two coats. Is it also normal to see bubbles in the sanding sealer when applied to the oak? Will the bubbles cease after more coats of sealer? should I keep applying the sanding sealer until I get a smooth coat with no bubbles? I will be putting miniwax gloss polyurethane for the finish. 

Thank you.


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## cabinetman (Jul 5, 2007)

MJP said:


> I'm starting a new project with red oak. I am using Miniwax sanding sealer on the bare oak. How many coats of sealer should be applied to the wood? So far I have applied two coats. Is it also normal to see bubbles in the sanding sealer when applied to the oak? Will the bubbles cease after more coats of sealer? should I keep applying the sanding sealer until I get a smooth coat with no bubbles? I will be putting miniwax gloss polyurethane for the finish.
> 
> Thank you.



You didn't say how you "applied" the sealer. If you want a super slick finish, use a grain filler. You could just thin the oil base polyurethane as a sealer. If you brush your finish, getting bubbles are likely. For oil base products, wiping gives better results.












 









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## del schisler (Nov 5, 2009)

MJP said:


> I'm starting a new project with red oak. I am using Miniwax sanding sealer on the bare oak. How many coats of sealer should be applied to the wood? So far I have applied two coats. Is it also normal to see bubbles in the sanding sealer when applied to the oak? Will the bubbles cease after more coats of sealer? should I keep applying the sanding sealer until I get a smooth coat with no bubbles? I will be putting miniwax gloss polyurethane for the finish.
> 
> Thank you.


I do this all the time. I don't use minwax sanding sealer tho. I use M.L.Campbell lacquer sanding sealer. No bubbles on that. I bet you used a brush? One coat should be enough. Sound's like you are doing a open grain finish which mean's it is going be ruff getting a smooth finish . You should have use shellack first to fill the open grain than you would got a smooth finish. As far as bubbles sand them out and apply the finish coat. You shouldn't see them . Sand them tell they are like nibbed out or blind in .The finish coat will go on good Sand in between coat's I use 400grit but 180 or 220 should work for you. I buy mine in 100 disk's 6" is what i use all different grit's . One problum with putting to many coat's it may do the hair line crack's later . This happen's with lacquer. I don't use poly take's to long to dry for me. good luck


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## MJP (Nov 4, 2010)

I have very little experience in finishing, but yes my goal is to get a smooth glass like finish. I did not actually start the project yet, I used the sealer on a scrap piece of oak plywood that I had to test it out. I applied the sealer with a foam brush. 3rd coat already and I'm getting bubbles. Its very frustrating that I cant get the hang of it. Exactly what should I do to get that glass like finish? I am using a 8x4 oak plywood sheet from lowes. I don't know all the terms so I'm not sure if its opened grain or what ever the term is for it. How should I go about finishing the plywood oak to get the results I want? Is shellac the same as the sanding sealer? would grain filler be better? I also did try the the thinned poly shirt method in the past but I got tiny little bubbles in my top coat. Whats the best ratio to thin the poly for the t shirt method? Maybe I'm just not thinning it enough. Thanks for helping me out.


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## cabinetman (Jul 5, 2007)

Here's my suggestion. Use a solvent base grain filler. Follow the instructions on the can. Then use your stain opr dye if you wish. If you want an oil base polyurethane finish, thin the first coat 50% with either mineral spirits or naptha. Second coat 25%. Coats thereafter about 10% using a neatly folded "T" shirt material to wipe on. It could take 4-5 coats to get the finish you like.

If you want a piano type finish, it has to be wet sanded and rubbed out with compounds, and is a royal PITA.












 









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## Rick Mosher (Feb 26, 2009)

I'll bet you're brushing that sealer right from the can? The real trick to finishing with any sealer is to thin it way down for the first coat (at least 50/50 maybe more depending on the sealer). Called a wash coat by many and used for many things including blotch control, it will also eliminate bubbling in porous woods. As Cabinetman said a paste filler is the answer to filling your grain.

I like Sherwin Williams grain filler because you thin it with VM&P Naptha and it dries in just 4 hours. I also like to stain first and then apply a wash coat of sealer before applying my paste filler (With a dark colored stain the filler will need to be tinted to the color you wish your grain to be). This prevents a disaster called gray pore which can occur when paste filler is applied to raw wood. The other advantage is the filler wipes off MUCH easier when applied over a wash coat of sealer, you can even use a squeegee to take it off very clean and fast.

On oak to get a closed pore finish you will probably have to do 2 applications of filler. (Do not seal between coats of filler) On some brands of filler you will need to sand between coats with Sherwin Williams you do not sand so you must wipe the filler off really clean.

Once the filler has dried apply a full coat of sealer, let dry, scuff sand with 320 grit 3M tri mite sandpaper and then begin applying full coats of whatever your top coat finish will be (the build coats should be gloss if your final coat will be satin wait until the final coat to apply it). After each coat dries sand with the 320 sandpaper dry using a sanding block so that you level the surface, being VERY careful not to burn through the finish to the sealer or raw wood. 

After you have applied enough coats that there are no shiny areas in the grain after sanding you are ready for your final coat. When that dries you can either leave it as is, rub it out or buff it to a high gloss depending on the look you are after. You are on the right track by making samples before you start on your project. I would continue to do so.


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## cujo8 (Apr 18, 2011)

What are the benefits of thinning the polyurethane for the 1st and 2nd coats as mentioned above? I have always just followed the directions on the can and I've never read about thinning the PU before. I know this is an older post, but hopefully someone hear can answer this question for me. Thanks.


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