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Perfecting poly finish??

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Forum topic by watermark posted 457 days ago 1081 views 0 times favorited 18 replies Add to Favorites Watch
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watermark

395 posts in 567 days


457 days ago

Topic tags/keywords: finishing end grain slab

I am working on a coffee table made with a cross cut slab so the top is all end grain. I am trying to finish with wipe on poly and I am having trouble getting it to the point I think it needs to be at to sell. Looking at it from above in normal light it is good but when I get down and look across it with sunlight or a flash light I can see blemishes.

I am using 600 grit sandpaper between coats to smooth it out.

Is that normal because it’s end grain? I already sanded back to bare wood and started over once because I wasn’t satisfied but I am getting the same results this time too.

Thanks for any ideas I have read through many other forum post regarding wipe on poly but couldn’t find an answer.

-- "He who has no dog, hunts with a cat" Portuguese proverb


18 replies so far

View Fred Hargis's profile

Fred Hargis

1711 posts in 1117 days


#1 posted 457 days ago

I don’t know what you mean buy “blemishes”, but if it’s imperfections in the finish (as opposed to the wood), remember that wipe on varnish builds much more slowly than any other application method. Some claim 3 coats wipping to 1 coat of brushed. Typically when I’m trying to get a perfectly smooth finish with varnish I’ll apply 3 brushed coats, then sand back, and repeat. Look for shiney spots after you sand back….they represent low spots in the finish layer that haven’t been filled yet. Once they disappear, you have a smooth finish…for me then it gets one coat of wipe on to bring back the gloss and I’m done. (I typically brush varnish thinned 20%, and the process I just described is very slow since you have to wait for the varnish to cure between sandings…usually several days). I don’t know if it will help, but here’s a short article on wiping varnish written by Bob Flexner

-- Our village hasn't lost it's idiot, we sent 'em to Washington.

View CharlieM1958's profile

CharlieM1958

15683 posts in 2842 days


#2 posted 457 days ago

Ditto what Fred said. It can take a long time to build up a perfectly smooth finish on a porous surface.

Aside from just using multiple coats, you can also speed up the process a bit by starting with a clear grain filler like CrystaLac.

By the way, photos always help.

-- Charlie M. "Woodworking - patience = firewood"

View PurpLev's profile

PurpLev

8476 posts in 2273 days


#3 posted 457 days ago

it being end grain – the pores will suck that finish right in, some spots more, some spots less which will leave you with an uneven surface.

you would want to fill in those end grain pores with a (appropriate) wood filler, or with shellac and some wet sanding between coats to seal in those pores before you apply that poly.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

View NiteWalker's profile

NiteWalker

2709 posts in 1201 days


#4 posted 456 days ago

I usually do a coat of sealcoat (dewaxed shellac) first. It seals the pores so the finish will be even.

-- He who dies with the most tools... dies with the emptiest wallet.

View CessnaPilotBarry's profile

CessnaPilotBarry

885 posts in 734 days


#5 posted 456 days ago

Ditto on Fred’s suggestion on brushing the initial coat(s) of varnishes. It’s easy to correct defects in early coats, and it builds much faster. Once you’ve got an even base, finish and set your sheen by wiping.

Many years ago, I was taught a fast “French Polish” method, consisting of a varnish layer that was sanded smooth, followed by a rubbed-on layer of shellac or Qualasole. The initial brushed-on layer saved many hours of rubbing to build the finish. It’s not the traditional way to do it, but it left a fantastic looking, but more durable, tabletop finish.

-- It's all good, if it's wood...

View watermark's profile

watermark

395 posts in 567 days


#6 posted 454 days ago

Thanks for all the ideas. Hopefully I get a finished shot up here soon

-- "He who has no dog, hunts with a cat" Portuguese proverb

View watermark's profile

watermark

395 posts in 567 days


#7 posted 424 days ago

OK I followed the advise and had what I thought was a nice finish looking at it in the garage where I finished and waxed it but woke up to a a scratchy mess. Looking at it was real nice but then from certain angles it was just a mess of really fine scratches so I went back and wet sanded from 320 to 600 grit and finished up with 0000 steel wool and same result looks good straight on but get down and look across it with the right light and it’s a mess of really fine scratches.

not sure if it comes through in the pic. Any ideas are greatly appreciated. I assume I am doing something wrong with the wet sanding or steel wool.

-- "He who has no dog, hunts with a cat" Portuguese proverb

View Wildwood's profile

Wildwood

982 posts in 759 days


#8 posted 424 days ago

Hard to tell from the photo of sanding marks in the wood or finish looks like you got rid of dust nips leaving pits in finish.

Before applying finish always wet the surface looking for sanding scratches in wood. Often take project outside in sunlight because of poor shop lighting and old eyes.

I always allow a day between re-coating surface with finish & light sanding. I seldom wet sand between coats. Use 320 or 400 grit silicon carbide wet/dry paper. I change paper often if necessary. Always wipe down and vacuum surface between coats.

I add a bit of dish washing soap to water whether using 600 or 1,000 grit silicon carbide wet/dry paper or 3M Softback Sponge to finish the finish.

I make my own wiping varnish/poly because most commercial products more than 60% dryers & solvent to resign. Normally start out with 50/50 mix of poly/solvent for first coats. Rule of thumb for me is 2 coats of wipe-on equals one coat of film finish. I use simply kitchen measuring cup to mix.

-- Bill

View upinflames's profile

upinflames

82 posts in 786 days


#9 posted 424 days ago

Get the elbow grease out and sand her back down, ROS will work to get back to raw wood. Once you’re there, get the card scrapers out.

If you don’t have scrapers, then the elbow grease comes in, hand sand up to around 320grit. The hand sanding will eliminate any swirls from the ROS.

Then you can go with the grain filler of your choice.

What ever you choose, wipe on or brush, should work better.

View shipwright's profile

shipwright

4897 posts in 1422 days


#10 posted 424 days ago

On a difficult surface like end grain you might consider a first coat of epoxy. Think of it as really thick varnish that dries hard over night. One coat is usually enough to sand back to “no shiny spots”. I use it over delicate marquetry when I’m afraid that sanding further to completely flatten it may sand through the thin veneer. You can then French polish, varnish, wipe or whatever you wish.

-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fiberglass trees. http://prmdesigns.com/

View David Dean's profile

David Dean

508 posts in 1523 days


#11 posted 423 days ago

A brush and steel wool this table top toke about 4 coats.

View Holbs's profile

Holbs

515 posts in 653 days


#12 posted 423 days ago

dean… that picture is so small! the postage stamp sized pic looks beautiful with that finish. can re-post to make it bigger?

View David Dean's profile

David Dean

508 posts in 1523 days


#13 posted 423 days ago

Sorry but my hard drive bet the the big so I got this off my cell phone.

View BLarge's profile

BLarge

115 posts in 1086 days


#14 posted 418 days ago

Do you want a soft, even finish on it?

I just finished a white oak table top that is flat, consistent, soft and satin sheen. I didn’t fill the pores, but I put on about 5-6 nice generous wet coats on so the pores would gradually be filled. I then wet sanded that back so it was flat (so no shiny spots). I then put on two more wet coats, wet sanded them flat up to 600 grit. To finish, I rubbed the finish out with 0000 steel wool and Wool Lube, with the grain.

It turned out amazing, it really breathtaking. The thick brushed Poly will enable you to fill those dip in your finish, and give you a flat surface to rub out to any sheen you want.

Wipe on Poly just build to slow for a Coffee Table or Dining Table, where you need a pretty thick film finish to take the bings and bangs.

View DaddyZ's profile

DaddyZ

2380 posts in 1665 days


#15 posted 418 days ago

On a Couple of tables I have done, I put the coat of poly on, then brushed on a coat of paint thinner.

The paint thinner seemed to raise the poly then evaporate back down with a very nice finish. I don’t mix the 2, 1st coat straight poly – 2nd coat straight thinner. Thinner applied while poly still wet ASAP

Click for details

-- Pat - Worker of Wood, Collector of Tools, Father of one

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