# Poly finish effort turning into gooey mess -- help..



## river251 (Dec 11, 2011)

Hello, I am building a computer table. I had a hickory veneered MDF top cut out, it is (was?) beautiful. I brushed on one coat of sanding sealer, using a foam brush, on the advice of the shop that made the top. Then I sanded the sealer with 400. Then I put on coat after coat of poly, sanding each one when dried with my dual orbiting sander and 400 grit, then 220 grit on the later coats. It was looking good. There were some low spots that didn't seem to fill in so I had the bright idea of pouring little puddles on the low spots. Instead of helping, I ended up with thick ridges around the edges of the puddles, that would not dry. I scraped these areas off with a putty knife. Then, it seems in these areas that the poly does not want to stick. Really I'm not sure what the problem is now, but I have areas that when I sand, just gum up. Maybe I am not letting coats dry. Maybe there is something that is acting like oil to water -- it's repelling the poly, but I don't know what. It seems to bubble up in areas when I apply it instead of going on smooth. The problem started when I did the puddles. Just now I scraped the gooey stuff as well as I could, then took some mineral spirits on a rag and tried to dissolve away the gooey parts. At this point I don't know what I am doing, or what to do.

What should I do now to save this project? Wait several days to let things really dry well and sand? Sand back to wood and put on another coat of sanding sealer (I am afraid something has gotten into the wood and that won't help, and I'm afraid of sanding through the veneer). 

Any help very very very appreciated....

Jim


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## jigs-n-fixtures (Apr 28, 2012)

You might try wiping it down with whatever is recommended as a thinner. 

You most likely have it on too thick, and/or built your layers too quickly resulting in it not drying completely between coats. Now that the surface has cured off it is nearly impermeable, and the finish below can't cure. I

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## tc65 (Jan 9, 2012)

Stop what you are doing and let it dry. For at least several days and maybe a week or more. Any raised areas can be carefully sliced off with a razor blade that is held almost horizontal. If any of the raised areas are still gooey when you try to slice them off, wait some more to let them dry. Poly will not "melt" into already dry areas, hence what happened when you tried to fill low areas. Once everything is dry and your puddles removed, re-sand the piece flat and restart the process of applying poly and sanding between coats. I would not use a power sander to sand between coats, rather use a good flat sanding block.


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## Rick C. (Dec 17, 2008)

+1 What trc65 said. After you sand it down try thinning your poly with Mineral spirits if it's oil base poly, I like 50-50 some don't cut it that much, and wipe it on. You won't have the brush marks or low spots. Don't be in a hurry, let it dry over night. Sand lightly, I like to use maroon scotch brite pads with a sanding block. Hickory is a tight grained wood, I would not have used a sanding sealer.


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## sawdustfactory (Jan 30, 2011)

Also, sand with 220 after sanding sealer. Use 320-400 between coats, lightly.


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## Fred Hargis (Apr 28, 2012)

I'm thinking you need to let it cure out, but I doubt several days will do it. It may take a week or even 2.


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## Steve Neul (Sep 2, 2011)

I would have to agree to stop and let the finish dry. If you keep going you might be in a situation where the finish might takes months to dry. Once dry you should be able to work the finish down with 220 grit paper with a block of wood behind it. I wouldn't recommend using 400 grit paper between the coats of wood finishes. That paper is more suited for water thin automotive finishes. 

I think you would be much happier with your finishing work if you would purchase a air compressor and sprayer. I believe if you use coupons you could get a compressor, hose and sprayer at harbor freight for around a hundred bucks that would do small projects. These small cheap compressors just won't provide enough air for larger projects. The air will run down and you end up having to stop and wait for the compressor to catch up.


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## river251 (Dec 11, 2011)

Thank you all so much. I am going to just forget about it for two weeks. I'm in Las Cruces, NM, one of the lowest humidity places in the country. In two weeks I'll come back and look at it.

Yesterday I used a putty knife to scrape off almost all of the gooey stuff. I just looked at it, and it seems pretty dry. 

When I come back I'll try sanding it down flat then apply poly-mineral spirits 50/50 and see if that thin coat "takes." If so I guess I am back in business, and I'll apply coats thinner and let each dry for a day.

Why does everyone recommend against the dual action sander, preferring hand sanding? With 400 there seems little danger of sanding through the poly.

When I have sufficient coats, how do I get a glass-like finish? Just let the last coat dry and be satisfied with that? Can I use polishing compounds with the DA to get a glass-like finish like I do on my car?

Rick, I thought about wiping it on, but was afraid of lint. Can you recommend a type of rag that won't have this problem? The foam brushes do leave brush marks.

Thanks very much again everyone.

Jim


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## Steve Neul (Sep 2, 2011)

river251 said:


> Thank you all so much. I am going to just forget about it for two weeks. I'm in Las Cruces, NM, one of the lowest humidity places in the country. In two weeks I'll come back and look at it.
> 
> Yesterday I used a putty knife to scrape off almost all of the gooey stuff. I just looked at it, and it seems pretty dry.
> 
> ...


Adding thinner to varnish is only going to add to your troubles. Brushing varnish, it should not be thinned at all. When sprayed it should only be thinned enough to get it to spray. Adding thinner screws with the integrity of the finish and makes it dry slower than it already does. Its best to use very soft conventional paint brush and brush each coat on thin. There is a greater risk of sanding through the finish with an electric sander however since you have the finish uneven I would probably use one myself. I don't get aggressive, I just sand over the finish like nothing is wrong. The sander will naturally take more off on the high spots. To get a glass like finish like your car applying the finish with a brush will take a lot of hand work. What you will have to do is put too much finish on and hand rub the brush marks off. Once you get sufficient finish on, start with the 400 grit paper with water and sand it until you get the majority brush marks. Then go to a 600 or 800 grit paper and wet sand it again. Then go to 1000 grit, then 1500 paper and wet sand it. Now using rubbing compound either hand rub the finish or better use a lambswool pad on a autopolisher and buff the gloss on.


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## river251 (Dec 11, 2011)

Steve, thanks much. You say varnish, but does this apply with poly too? It's Minwax poly from Home Depot. Not sure if that classifies as "varnish." 

So once it's good and dry, sounds like I can progressively sand it with finer grit, then finally with rubbing compound. Good to know, I really want a glass texture, instead of a wood grain texture. 

Thanks,
Jim


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## dustmagnet (Jul 12, 2012)

I'm just going to throw a couple of things at you.
1. apply the poly with a natural bristle brush, you will see a noticeable difference from the foam brush. I use both and have never had brush marks with either(poly is designed to be put on in THIN coats).
2. the only reason you sand between coats of poly is to remove any dust nibs, bubble pops, or any other foreign material that may have landed before dry. There is no need to get aggressive at all when doing this, I use steel wool, then wipe with a DAMP mineral spirit rag,(DO NOT use steel wool with water based stain or water based poly).
3. if you want a glass like finish, depending on the species of wood, anywhere from 4 coats to however many you want to put. I put a minimum of 7 coats on my furniture.
4. when wanting a semi-gloss or satin finish, always start with clear gloss and use the semi or satin as the last coat, this will keep your work from looking milky and just plain crappy.


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## Steve Neul (Sep 2, 2011)

river251 said:


> Steve, thanks much. You say varnish, but does this apply with poly too? It's Minwax poly from Home Depot. Not sure if that classifies as "varnish."
> 
> So once it's good and dry, sounds like I can progressively sand it with finer grit, then finally with rubbing compound. Good to know, I really want a glass texture, instead of a wood grain texture.
> 
> ...


I'm sorry, oil base polyurethane is a type of varnish and I just used varnish as a shortcut word. You work either the same way.

In the future if you have a piece like walnut or mahogany and even oak and you want to get rid of the wood grain texture you should first fill the grain with a pastewood filler. It's kind of a thin wood putty you brush on and rub the excess off with a rag. It will fill the open grain so it will finish faster. Trying to fill the grain with the finish will take several extra coats. Anyway each time you sand the finish and apply a coat of finish it will get more level. You just have to be sure each coat is thoroughly dry because if you put a coat over the top of one that isn't quite dry it will almost stop drying and could take months to fully cure. With most varnishes and polyurethane finishes you shouldn't put more than one thin coat on in a 24 hour period under great conditions. If the weather is cold or humid it could take 48 hours or more to dry.


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## Rick C. (Dec 17, 2008)

Steve, I have to disagree with your point on thinning poly. I never use to thin it and always got it on too thick, it left brush marks, bubbles and took forever to dry. A few years ago I was told to thin it 50-50 and wipe it on with a lint free cloth (you can get them at any big box store). It takes 20 minutes or so to dry enough to pick it up and hang it to finish drying. There are never any streaks, bubbles or runs. 
River251,I'd like to recommend a book called Understanding wood finishing by Bob Flexner. I've had it for a few years and it's been a project saver for me.
Never have I heard or read that thinning poly with mineral spirits screws with the integrity of the poly, there's already mineral spirits in poly. On large pieces I brush it on with a foam brush then use my cloth to wipe it even. It takes about 4 coats and I lightly scuff it with maroon synthetic pad(don't like using steel wool) between coats.
When the final coat dries, if I want less sheen I use a black synthetic pad and "buff" it.


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## cabinetman (Jul 5, 2007)

To fix what you have now, you have to let it sit until dry. Like its been stated it could take weeks. It has to sit long enough for all previous coating to cure. You can check it with 320x open coat sandpaper and if the paper sticks as its moved around instead of making white powder, it ain't dry. 

Once it is dry use 280x - 320x wet-or-dry silicone carbide sandpaper (the dark gray stuff) and water with a block to sand out. Oil base varnish/poly needs to be scuff sanded between applications to get better adhesion. 

When you're ready to continue, I wouldn't use a brush, but rather a "T" shirt type smooth cloth folded in a neat square pad, and thin the varnish/poly about 30% with VM&P Naptha, and wipe smooth even paths. Allow each application to dry thoroughly. Scuff sand between applications with 320x open coat sandpaper...it's light gray silicone carbide...called "no-fil", or "fre-cut". 

When you have a sufficient build of finish, use the wet-or-dry paper and water starting with 400x and you can take it to smoother grits, like 1200x, 1500x. By that time it takes very little rubbing with a rag and a smooth rubbing compound that you can get at any auto supply store.

I wouldn't consider spraying an oil base varnish/poly at this time unless you practice with it and the spray equipment. It's heavy bodied and can run very easily.








 







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## cabinetman (Jul 5, 2007)

I would also like to add that I wouldn't sand it with any kind of power sander either electric or air. The reason being, that the finish will warm up and has the propensity to stick to the sandpaper. This can lead to it building up on the paper, and creating scratches.










 







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## Fred Hargis (Apr 28, 2012)

Rick C. said:


> River251,I'd like to recommend a book called Understanding wood finishing by Bob Flexner. I've had it for a few years and it's been a project saver for me.


That book (and/or the one by Jeff Jewitt) should be at the top of every woodworker's list of things to have in the shop.


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## Steve Neul (Sep 2, 2011)

Rick C. said:


> Steve, I have to disagree with your point on thinning poly. I never use to thin it and always got it on too thick, it left brush marks, bubbles and took forever to dry. A few years ago I was told to thin it 50-50 and wipe it on with a lint free cloth (you can get them at any big box store). It takes 20 minutes or so to dry enough to pick it up and hang it to finish drying. There are never any streaks, bubbles or runs.
> River251,I'd like to recommend a book called Understanding wood finishing by Bob Flexner. I've had it for a few years and it's been a project saver for me.
> Never have I heard or read that thinning poly with mineral spirits screws with the integrity of the poly, there's already mineral spirits in poly. On large pieces I brush it on with a foam brush then use my cloth to wipe it even. It takes about 4 coats and I lightly scuff it with maroon synthetic pad(don't like using steel wool) between coats.
> When the final coat dries, if I want less sheen I use a black synthetic pad and "buff" it.


I've had just the opposite experience with thinning poly. Primarily I was thinning it for spray purposes but thinning is thinning. I started using polyurethane after being used to using lacquer so I attempted to work it pretty much the same. I soon found out the more thinner I would add to poly the longer it would take to dry and would stay gummy where if I used it un-thinned it would dry hard. Also the sheen would become inconsistent. It would be dead flat in spots and semi-gloss in others. I suspect the over thinning allowing the flatting agents to settle. I had a discussion with the manager of my Sherwin Williams about it one time and he was the one that said over thinning screwed with the integrity of the poly. From the experience I was having I had to take him at his word because when I started using as little thinner as possible the poly worked so much the better. I do some house painting too and when finishing woodwork and doors inside of a house I normally brush the poly due to overspray problem. I don't have any problems with brush marks using polyurethane unthinned. I use a very soft paint brush and brush each coat on as thin as possible.


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## Rick C. (Dec 17, 2008)

Steve, trust me, I wasn't trying to step on your toes. I don't brush anymore because of my own inadequacies. I simply am not able to judge what's enough. Wiping takes the guess work, and mistakes out of the equation. I don't spray because it is either too dry and sandy looking or I feel it needs to be just a little wetter, to avoid the sandy look, and it runs. I don't have time or patience for rework and wiping works for me.
I've never tried naptha to thin poly, How is it different from mineral spirits? I may give that a try. I usually do use old t-shirts as a pad.
I either use satin or semi-gloss poly, not looking for a glass like finish. There has been no need to go through the extra steps to fine polish the finish. A project I have coming up is a dining room table and I'll have to then.


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## cabinetman (Jul 5, 2007)

Rick C. said:


> I've never tried naptha to thin poly, How is it different from mineral spirits? I may give that a try.



It dries faster than mineral spirits.









 







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## jack warner (Oct 15, 2010)

thinning is not the answer. go pick yourself up some japan dryer. poly/varnish should never be mechanicaly sanded,+1 with c-man, hand sand only with now finner than 220. 
if your brushing and need things to flow better, use flood penetrol, never thin. penetrol will let you brush into its self without pulling or dragging.


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## jack warner (Oct 15, 2010)

ps
the proper way to apply a poly is
1st coat thinned 40 or so %
this allows th poly to soak in and grab your wood
2nd coat about 25%
this is a building coat. thinned to grab your first coat
final coat not thinned.

each coat needs to be sanded with 220 except the last. poly doesnt stick to it self well.

spraying will always give the best finnish. i spray everything


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## river251 (Dec 11, 2011)

jack warner said:


> thinning is not the answer. go pick yourself up some japan dryer. poly/varnish should never be mechanicaly sanded,+1 with c-man, hand sand only with now finner than 220.
> if your brushing and need things to flow better, use flood penetrol, never thin. penetrol will let you brush into its self without pulling or dragging.



What are Japan dryer and penetrol? How do you use them?


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## river251 (Dec 11, 2011)

Thanks for the recommendation of the book. I do enjoy woodworking though my projects are infrequent and usually when I need to build something, like with this PC table. Nobody makes anything like it so I have to build it. 

I'll pick that book up.

Jim


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## jack warner (Oct 15, 2010)

river251 said:


> What are Japan dryer and penetrol? How do you use them?


penetrol is a oil adative used for making oil base paint/varnish/poly flow better, and makes workability longer. it will also give the impressoin of thinning. basicly the same as flotrol for latex. japan dryer is just that it reacts with the chems in paint/poly/varnish and makes it dry/set up faster. the jap dryer use only as directed adding too much will cause problems. also in white paint it can/will change the color a little.


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## river251 (Dec 11, 2011)

I came here to ask a different question, and thought I'd update this thread. I came down with a respiratory issue so have stayed away from the Poly just in case. So, the computer desk top is as I left it, and has been drying a month or two now. When I can get back to it, I will follow the advice I received on this thread, thanks.

Jim


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