Sanding between finish coats and final buffing - polishing

[Sean Rainaldi]

Hi there,

Finally seeing the light at the end of the tunnel here. After building 16 kitchen cabinets I have most of my raised panels built and now comes the final coats of finish. I'm doing hard maple and applying the Target Superclear 9000 gloss clear coat, and for finish sanding I used 180 grit for my final sanding of my work, prior to painting, and I am hand applying by brush, using a good quality DaVinci Top-Acryl series acrylic brush that the guy at target recommended if I intend to hand paint.

So my questions are, what is the best size grit paper to use to sand the finish between coats? I was thinking starting with 220 and then go up to maybe 320, but is that too coarse?

I was hoping to get this done with either 3 or 4 coats, is that enough?

Also, for the final polishing or buffing of the final (top) coat, are there any recommendations as to what method or product to use to bring my raised panels and face frames to a nice shiny, polished and smooth finish?

I remember seeing this buffing pad at Woodcraft several months ago, I forgot the name of it, it was billed as a microfine buffing pad to use on a orbital sander to buff out a finish and make a mirror like finish, would that be a good way to go?

Thanks for any insights.

[Jeff Monson]

I sand with 320 between coats, that will leave you a really nice smooth finish, I would think 4 coats will be more than enough.

[Phil Phelps]

Sean, I'm confused, as usual. You are "painting", meaning color? Why did you clear coat the raised panel doors? 220 on the prime coat and 300 between finish coats will be fine.

[Sean Rainaldi]

Hi Phil sorry, I meant applying clear coat when I said painting. I'm not painting with any paint, just applying clear coat that's all.

[Kelly Craig]

I just finished a table top, including leaf, with five coats of Varithane.

I scuff sanded between coats and worked to even the brush strokes on the last, using 400. I just used water as the lubricant for sanding.

Finally, I just mixed up some rotten stone with water and fired up my Porter Cable random orbit polisher, running at about position two on the speed control (one up from the minimum).

After wiping this off, I applied plastic polish from and auto parts store (a little more water) and buffed away.

An hours work, total and it looks like a spray job.

(Sometimes I use pumice before the rotten stone. )

In the old days, I used my air compressor and a die grinder with a buff wheel. I tried to keep below 1200 RPM and move fast, keeping the surface wet. It was messy, but it worked.

All this is more interesting in that my brush was a detailer's nightmare. It was left in the cleaning bucket to become part of the gel that forms when you put a brush into thinner. My idea of cleaning was to run it up and down my cyclone fence, knocking off most of the gel.

After several coats had dried, you could remove dead (and live) skin by running your hand over the bumpy table top. However, when the sanding and polishing was done, you would never have known that.

[Sean Rainaldi]

Pardon my ignorance, what do you mean by rotten stone?

[Phil Phelps]

Sean, as I understand, you want to clear coat raised panel doors with a high gloss, waterborne product, sand and then buff and polish. Sean, this just is not practical. You don't buff surfaces like a raised panel doors. If you use a brush, you'll end up with brush strokes on the doors and using a waterborne product, you'll have plenty of them. If you sand them smooth and re-coat, you'll have the same problem. The best you can do is with an oil base product. You'll have better results with far less brush strokes. I think you should re-think your position and spray the doors with a lacquer product. I'd also think twice about using a gloss finish. It will reflect light and magnify every imperfection. Satin or low luster would be my choice.

[Rob Cunningham]

220 grit between coats of SC9000 is too coarse. 400 is recommended. You might need to add some retarder to get it to lay out nicely with a brush. I've only sprayed it so I'm not sure, talk to Jeff at Target. I agree with Phil that buffing and polishing raised panel doors is not practical and a satin finish would be a better choice.

[Sean Rainaldi]

Hi thanks all sorry for the delay.

I agree with you on the brush strokes, I am finding it's hard to get rid of them. I can sand them out and end up with a fairly nice satin finish, not good enough for a top coat though.

Actually though, I called and spoke with Jeff at Target this past April, long before I started this thread. I asked him what was the best of his product line to use if I intended to brush it on and he recommended the Target Superclear 9000 and also recommended using the DaVinci Top-Acryl series acrylic brush. Unfortunately I don't have a good spray gun or compressor and I already started applying finish long ago on the face frames of all the cabinets which already have two coats, as well as many of the raised panels, so I guess I'll have to finish up this way if at all possible.

http://www.sawmillcreek.org/showthre...=108538&page=2


Hopefully I will be able to get it to come out looking OK; maybe if I buff it out I can come up with a good satin finish, buff the top coat will dull up the finish a bit, make it a bit satin, which would be fine, as long as it is uniform and does not show strokes and any drips I think I will be happy. Or if I use Kelly’s method.

At any rate, can anyone tell me what Kelly meant above by rotten stone? I am also wondering, can I mitigate or reduce brush strokes on the top coat by thinning out the top coat? If so, any recommendations as to what kind of a thinner to use? Should I use a foam brush for the top coat? Any recommendations of a buffing or polishing pad for the top coat - either hand or for my festool Rotex?

I’ve got three coats so far on some of my pieces so getting ready to finish up…

[Tony Bilello]

At any rate, can anyone tell me what Kelly meant above by rotten stone?
…

Rottenstone is a very fine abrasive. Normally used in the final stage of buffing to a mirror finish. This is used right after buffing with pumice. Pumice is used as the final stage of buffing for a satin finish. Pumice and rottenstone can be purchased in a powder form but usually it is purchased in an oil slurry and used directly out of the can.
In todays world, you buy kits from automobile stores or woodworking stores usually in 3 bottles. Each bottle contains a different grit and the final (3rd bottle) will give the mirrow finish.
I personally have only used the stuff I buy in cans already suspended in an oil solution. I have never used the 3 can kit. Maybe someone else on here can help you.

[Conrad Fiore]

Sean,
You would thin the 9000 with water since it is a WB product. You might also want to try to add some SA5 retarder from target to help flow out the brush marks. I would agree that a satin or flat finish off the brush might be the way to go to help hide any brush marks. Why don't you try a sample with your complete finish schedule and try thinning the last coat at different percentages to see if you can't get the final coat to flow out so you don't have to do any buffing or polishing.

[Prashun Patel]

I've used rottenstone and pumice. It's messy. I've been able to achieve good results with quality abrasive paper. I've never tried it, but look at the Micromesh products.

As far as sanding between coats, I'd use 400

[Sean Rainaldi]

You would thin the 9000 with water since it is a WB product.

Conrad (or anyone), should I use distilled water? Or does it matter?

[Conrad Fiore]

Distilled if you like, no reason to unless you have some pretty funky tap water.

[Sean Rainaldi]

Thanks Conrad.

What ratio of water to Superclear u recommend?