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Rubbing out wipe-on poly on cherry

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Forum topic by maymay posted 02-11-2018 04:02 PM 659 views 0 times favorited 10 replies Add to Favorites Watch
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maymay

3 posts in 104 days


02-11-2018 04:02 PM

Topic tags/keywords: question

My husband and I are new to woodworking, loving it, but agonizing through some mistakes. We made an 11.5’ x 17” wood counter top out of gorgeous cherry. It spans 2 sets of cabinets which we also made. The middle 4’ is unsupported, and will be used as a desk. We applied 10 coats of wipe on poly, (1st 7 layers were gloss, then final 3 layers were satin) and sanding between coats with 400 grit paper. We then let it cure for 2 weeks. We want the final finish to be satin. After curing, we sanded with 1000 grit wet/dry paper and now see that there remain some tiny glossy spots and lines along some grain lines, within the more matte areas. We have read that we should sand until all the gloss is gone, but are afraid to sand through too deeply. Are we crazy to be worried about this with 10 coats of poly applied? The surface feels beautifully smooth, and looking at it in just normal light, it looks amazing, but when you look with a raked light, these areas are clearly present. How do you know when to stop??


10 replies so far

View Bill White's profile

Bill White

4930 posts in 3959 days


#1 posted 02-11-2018 04:28 PM

Steel wool (4 O) or a non woven pad? Pics will help us help you.
Bill

-- bill@magraphics.us

View bandit571's profile

bandit571

20005 posts in 2682 days


#2 posted 02-11-2018 04:47 PM

Just an old, lint-free T-shirt works wonders….

-- A Planer? I'M the planer, this is what I use

View jdmaher's profile

jdmaher

427 posts in 2578 days


#3 posted 02-11-2018 04:57 PM

I sand between very thin coats only to knock down nibs and ridges, and to provide just a little “tooth” for the next coat of poly to grip. That is, just a very light sanding to all BUT THE LAST of several thin coats.

Pictures would help, but perhaps your satin coats were a little too thin / uneven. If the glossy bits bothered me (actually, they probably would NOT), I might hit them LIGHTLY with some sandpaper, just to scratch the gloss. Clean off ANY dust / nibs. Then one more coat, even as I could, and “burnish” (more about “burnish” in a moment).

I’m sure your 10 coats are plenty of protection. Anything you do to that final coat is just cosmetic.

I’m usually pretty happy with the way a final satin coat looks. Nonetheless, I do “burnish” the final coat. That is, I rub out the final coat with hand-sized pieces of kraft paper (i.e., paper grocery bags). This clears away any final dust nibs, and does a bit of barely perceptible polishing. I go over the surface once, with moderate pressure and moderate speed. Flip to a fresh surface of the kraft paper and go over it again, with just a bit more pressure and enough speed to actually generate a friction warmth that I can feel in my hand. It may be just my imagination, but that heat SEEMS to add even greater smoothness to the final surface.

Remember, a counter-top WILL acquire minor surface scratches through use. To me, that’s the “character” that enhances its beauty.

-- Jim Maher, Illinois

View OSU55's profile

OSU55

1672 posts in 1988 days


#4 posted 02-11-2018 05:02 PM

You are right to be a bit concerned with going thru the finish – 10 coats sounds like a lot, but film thickness is very dependent on the product and viscosity (solids content) and how “wet” you wiped it on. You do not need or want to sand all glossy areas since you want a satin finish. If you wanted a filled perfectly flat glossy finish its a different story. You have probanly already sanded more than needed. Now rub it down with 0000 steel wool or fine gray and superfine white scotchbrite, you can sub in what you want depending on the actual sheen desired. I use a da polisher for this, makes so much easier/quicker. Auto polishes of different cuts (abrasive size) can be used to adjust sheen, but 0000 steel wool gives a nice satin sheen. Assume u used ob poly. Steel wool can be used after wb coats are all on, but if recoating is needed the steel can rust.

View Wildwood's profile

Wildwood

2305 posts in 2133 days


#5 posted 02-11-2018 05:06 PM

Depends upon amount of poly to thinner used in the product you used. I make my own wipe on poly using 50% poly and 50% mineral spirits. Two coat of this equal one coat of poly. Some commercial brands have as much as 70% thinner(MS) and other additives. Remember wiping on a thin layer of finish still the more you add takes longer to cure. Still want to avoid using too many coats due problems curing or cracking when fully cured.

Most full strength clear finishes reach 90% cure in nine or ten days and can take full thirty days to cure. Most people using oil based poly thin it 10 to 15% before application so all about temperature & humidity.

Know you used 1000 grit wet/dry paper you do not say whether you used water or oil to rub out. If used water helps if put a few drops of dish washing liquid in the water to break surface tension. Have used mineral oil & sandpaper to rub out a finish too!

Bottom line sounds like applies to much pressure while sanding without enough lubrication.

-- Bill

View maymay's profile

maymay

3 posts in 104 days


#6 posted 02-11-2018 06:51 PM

thank you all for your help and replies. in answer to some of the questions:

—we used minwax oil-based gloss poly that we thinned with mineral spirits ( 60% ms 40% poly ) and wiped on with tee shirt material. 7 coats of gloss, 3 coats of satin.
—after curing 14 days , we hand sanded with 1000 wet/dry paper with a dilute mix of dish soap in water. virtually no pressure, just guided the 1000 grit paper backed with a foam block

the finish is now uniformly smooth as glass to the touch.
we brought it up and set it on the cabinets where it will live. direct on with diffuse light you don’t notice it, it looks great, looking across into reflected light is where you notice it. it appears as reflective spots and lines that are mirror like. like looking out the window of an airplane and seeing creeks and rivers shining on the ground. maybe we just live with it.

i’ll try and get some pictures posted

thanks,
may

View LesB's profile

LesB

1726 posts in 3442 days


#7 posted 02-11-2018 07:05 PM

May,

Wipe on poly goes on very very thinly so 10 layers is not very thick so any unevenness in the surface of the wood (variations between hard grain and soft grain of the growth rings) is going to be transmitted through the finish. That is what I think you are calling the “rivers”. Several heavier coats of brushed or sprayed on poly which is self leveling would in most cases cover that up. Sand lightly between coats.
You could probably remove the gloss in your current “rivers” by burnishing with the grain with 0000 steel wool or white 3M pad and some wax. Buff the wax with a soft cloth when it drys…just a few minutes after application.

If it were mine I would sand it down with 320 or 400 grit paper to level some of those variations and then apply at least two, maybe 3, brushed or sprayed on coats of regular satin poly. Then after it is well cured (several days) burnish that with 0000 steel wool (or white 3M pad) and a carnauba wax. That should make it smooth as glass.

-- Les B, Oregon

View maymay's profile

maymay

3 posts in 104 days


#8 posted 02-23-2018 05:23 PM

Thank you so much to everyone for your input and suggestions. We have it in place and have lived with it now for a couple of weeks and we think it looks GREAT! The little issues don’t bother us at all. Throughout this project, we have learned an incredible amount from these forums and other info posted on the internet, and we want to thank all those people who take the time to answer questions and post info based on their experience. It helped us tremendously. We look forward to asking you guys many more questions through the years! Thanks again.

View Rick's profile

Rick

9600 posts in 3032 days


#9 posted 02-25-2018 10:43 PM

I would use a Brush On Poly. Probably Semi Gloss. WELL brushed in and smoothed out with 000 Steel Wool between coats.

10 Coats seems a bit excessive. Maybe Three Coats would be just fine. If not. You can always rub it down again and apply as many as you think are necessary.

Rick

-- LIFE is what happens when you're planning on doing Other Things!

View Rick's profile

Rick

9600 posts in 3032 days


#10 posted 02-25-2018 10:53 PM

I would use a Brush On Poly. Probably Semi Gloss. WELL brushed in and smoothed out with 000 Steel Wool between coats.

10 Coats seems a bit excessive. Maybe Three Coats would be just fine. If not. You can always rub it down again and apply as many as you think are necessary.

Rick

-- LIFE is what happens when you're planning on doing Other Things!

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