Finishing over Poly

[The A Train]

My wife and I have a farmhouse style table and benches and we (her) would like to refinish. The whole thing is finished with a high gloss poly. We (she) would like the bottoms painted and the tops satin and not gloss. My plans are to sand, prime, sand, paint the bottoms; but as to the tops Im unsure of the best route. Could I simply sand with my ROS to 220g and knock the sheen down, or could I wipe on satin poly over the current finish? This was a very expensive, to us, table and I dont want to royally screw it up. Any input is appreciated!


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[marinosr]

220 grit paper I think will give you a dead matte finish, too coarse. You can sand with 600 or 800 grit paper, and then rub out with #0000 steel wool. I can say from experience that the effort required for this should not be underestimated. You will get a much nicer surface though IMO than just putting on a coat of satin poly, although this will work too.

 

[junquecol]

I would look in Lowes for Citra Strip, and try some on a spot that won't be seen, as sanding can take a LONG time.

 

[JeffH]

The advantage of knocking back the gloss is that you retain the clarity of gloss poly -- satin polys usually have solids that kill the shine but also kill the brilliance of the colors of the wood. The net effect is kind of like the difference between glossy photo paper and matte -- the glossy will provide more contrast, letting you bring out the deeper tones in the wood grain. If you knock the gloss back with around a 400-600 grit, you should be able to keep most of the clarity of the original finish while taking away the shine.

I'd suggest hand sanding rather than using a sander -- more controllable, since you're only trying to add tiny scratches, not remove material. Go in the direction of the grain and remember that it's the number of passes, not the pressure, that does the job.

The trick is to do it evenly, though, or you'll have a splotchy looking surface.

If you don't care so much about depth of color, I'd say sand at 220 and then do a couple of light coats of satin poly, maybe even wipe-on.

 

[Gofor]

Another option for breaking the gloss on the top would be wet-dry paper or automotive rubbing compound. Start with a fine grit (600, 800, or even 1000) and just water as a lube. Rinse off and let dry to see the results. You can get small sheets of very fine grit wet-dry paper at most automotive parts stores. If you have a Car-Quest in your area, (or an automotive paint store) they usually have up to 2000 grit in full sheets

If the "high gloss poly" on the top is a factory finish, there are a lot of possibilities as to what that coating really is. It could be a water-borne acrylic, an oil based varnish, a two-component catalyzed coating, or even a catalyzed lacquer. Each has its own hardness and resistance to abrasion, so best to experiment first if you can.

Regardless of what you try for the top, I would experiment on the bottom portion first (if it is finished the same as the top) until I got the desired result. That area will get painted later, so will hide the experimentation. You may find a ROS is too efficient (i.e. aggressive) so you may do better with hand sanding with a rubber sanding block, altho a ROS will give a more even result with the very fine grit wet-dry paper.

If it gets messed up, you always have the option of resanding and putting a satin poly on it. If starting from bare sanded wood, build up the coating with gloss poly until you have an even gloss across the entire surface, and only use the satin for the final coat (brush application) or final two coats (wipe-on/spray), to achieve the best clarity of finish.

If going with the "satin" top coat, you may want to do a test piece first. Some brand's "satin" matches another's "semi-gloss". Also, your wife's "satin" may be different than what comes out of the can. Sometimes trying to communicate a desired level of gloss is like trying to nail jello to a wall.

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[CrealBilly]

Something to think about... even if you knock down the sheen to flat or matte, overtime you will get gloss spots from normal wear because the finish is gloss.

 

[Jeff]

The whole thing is finished with a high gloss poly.

Good advice for you so far and I'm curious as usual. How do you know that the finish is "poly"?

 

[ehpoole]

As mentioned you can use a very fine grit combined with wet sanding to knock down the sheen (start with something very fine, then get a bit more aggressive if the sheen is still not to your satisfaction), but you will likely find it easiest to first rough up the existing gloss finish and then recoat with several coats of satin polyurethane. The final coat determines the sheen of a clear coat, but using several coats reduces the concern of wear and tear for a good many years. The challenge with trying to create a satin finish through sanding alone is that if the table top is not absolutely dead flat (and wood seldom remains perfectly flat) you may find that you actually wear through some elevated areas before effectively scuffing the lower lying sections (which will also be influenced by how hard or soft your sanding backer pad is, which affects the degree to which it confirms to irregularities in height) which later recoating with several fresh will then repair. You will want a scuffed coat anyhow so that the new coat of polyurethane adheres well, so there is nothing to lose from experimenting with sanding first should you wish to experiment a bit.

 

[The A Train]

Thanks guys for all the replies and suggestions. And I apologize for not responding until now, but I have a 16mo, and 6wk old girls and time is one thing I dont have much of.

As for the table...I began by sanding the tops by hand with 400, making sure not to put much pressure on at all. I then sanded the bases with 220 by hand. At this time I began wondering why I even started in the first place. Next, I primed the base with an oil primer (zinser I believe). That stuff was incredibly thick and took forever to apply.

As that was drying I applied the first coat of wipe on poly. It hid most of the cloudiness I made from sanding but not all. Then I tackled the base with a latex enamel. This is the point I weighed out the pros and cons of taking up drinking...the cons won. So I finished with one last coat of the wipe on poly on the tops.

I believe it came out well, but in certain angles I can still see the cloudiness from when I originally sanded the tops. I hope I can buff the tops with some 0000 steel wool and itll go away. Either way its not terrible. I tried to get a pic to show it.

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[tarheelz]

Well done. My experience with table tops like this is that you will never be satisfied. You may find yourself coming back to it from time to time to "fix it." Know that everyone else who sees it, thinks it looks perfect.

 

[The A Train]

So it is showing a good amount of the cloudiness. Would a good wood wax help that?


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[StephenK]

We just finished a very similar process with a relatively cheap laminated farm house table. We sanded off the old finish and stained the wood to match a walnut island top I recently completed. My wife wanted to do this project on her own. She sanded, stained and began applying a gloss poly with a foam brush. The gloss poly looked really good, but it was just too glossy. So after letting a cure for a couple of weeks, I told her to sand at 320, then apply a wipe on satin poly. It looks "OK" but you can still see some cloudiness/streaking. My opinion is you need a high quality satin finish for the best results - Rubio Monocoat comes with high recommendations from personal friends. I used Behlen Rockhard Gloss for the island top thinned 50/50 with mineral spirits. I wiped on multiple coats and it turned out excellent.

For what it's worth, I wouldn't have sanded our table top other than to get to the laminate wood to stain it. TO just change the gloss, I would have coated with a blond shellac, then applied satin poly over top.

 

[McRabbet]

Stephen,

Several years ago I did a similar refinishing of an inexpensive veneer top kitchen table that had a Maple top. I carefully sanded off the old finish, taking care not to sand through the veneer. Sanded to 220 and removed dust with a tack cloth. Next I flooded the top with Behlen's Solar Lux Cherry Stain to alter the color to what SWMBO wanted. After the stain dried, I applied four coats of Behlen's Rock Hard Table Top Varnish, the first was cut 50-50 with Behkol solvent. I used a very good bristle brush to avoid bubbles (thin coats with brush held nearly vertical and not pressed down and bent as one would do with a coat of paint). I am typing this on that same table more than ten years later and water still just beads up on the surface if spilled. Best Table top finish ever.

 

[The A Train]

Update: so the table has been brought back inside. I went to good ol lowes and picked up some dark finishing wax and that cleared up the cloudiness I was seeing. It seems to have given the wood a richness that Im really liking. But I am finding it very difficult to remove. I removed most of it but I seem to be swirling around whats left and not really removing it. The plans are to let it sit overnight and try buffing in the morning


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[ehpoole]

So it is showing a good amount of the cloudiness. Would a good wood wax help that?


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Most of the cloudiness is likely from using a relatively aggressive grit (400) while dry sanding. The heat created by the cutting faces of the sandpaper during dry sanding partially melt (at the microscopic level you actually generate a good deal of heat at the cutting face, even if things only seem barely warm to the operator) and tear the plastic film, creating a lot of rough edges and potentially trapping a portion of the swarf within the original finish (you may also trap a microscopic bit of air as well). It helps, in my experience at least, to use finer grits and wet sand when your goal is to reduce the surface gloss. In fact, for semi-gloss I have used relatively coarse automotive polishing compound and a wool bonnet on my 6" random orbital sander. But it very much helps to be wet sanding versus dry sanding.

 

[Gofor]

Just for future reference,: The poly varnishes dry to touch and can be used fairly soon, but like any other varnish, they fully cure by oxidation (coating reacting with the oxygen). For this reason, it is best to let them fully cure (about 30 days) before using wax or even polishing out. The lower layers may not be near as hard as the top surface due to the oxygen level being much lower. This can result in the solvents from the wax affecting the lower levels, as well as when polishing, you can have hard coating in one spot and slightly softer in an area you have worked a little harder, making if very difficult to get a uniform sheen. I would recommend you let the table sit for about a month before doing anything else to it.

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