# Wiping Polyurethane Questions



## monty1975 (Apr 6, 2009)

I'm finishing a mahogany dresser and have started to use wipe on poly (glossy). The directions state three coats.

Well.... i'm at three coats and it looks bad - looks like I would expect after the first coat of brush on poly... glossy on the natural contours of the grain (this is African mahogany) and matte on the low points. It looks like there just isn't enough product on the surface of the wood. 

The first two coats went on so thin that I couldn't use sandpaper to scuff as color would show up on the sandpaper so I used some steel wool.

Do I have to build many coats with wipe on or am I doing something wrong? I hate to deviate from the instructions but 3 coats seems like far too few.

steps to this point.
strip, sand 100,150,220, raise grain, 220, water trans tint, poly

Thanks,
Brian


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## Fred Hargis (Apr 28, 2012)

That certainly doesn't seem like enough coats to me as well. I normally consider 3 coats of wiping varnish equal to about 1 coat brushed on. I typically apply it in sets of 3, let it dry overnight, then 3 more and so on. With wiping varnish, scuffing between coats of a set isn't really needed. But between sets (if it's a urethane product) is a good thing.


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## Steve Neul (Sep 2, 2011)

Much of the problem you are having is the african mahogany. It absorbs more of the finish then if you were doing pine and needs more coats. The manufacture can only give recommendations on the average use. From where you are if you got the same brand poly in a brush on version and put a coat or two of that on with a soft brush, then you could sand it and finish the job with the wipe on.


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## monty1975 (Apr 6, 2009)

Thanks for the tips guys. I picked up some brush on poly and will hit it with wipe on for the final coat or two. I'll do the dresser top wipe on only for the heck of it - i'm at 5 coats now and the finish is just starting to build.

I would have gone through 2-3 bottles of minwax wipe on for the small dresser at the wipe on only rate.

The gloss sure does make the African mahogany pop!
Brian


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## jjrbus (Dec 6, 2009)

http://www.woodworkingtalk.com/f8/rubbed-oil-confusion-34570/


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## DST (Jan 10, 2011)

Hopefully your water products won't react with your steel wool bits


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## monty1975 (Apr 6, 2009)

JJRBUS - I read that whole thread and while I am sure there is tonsw of good info there, it's a bit over my head.
DST - I actually used a maroon scotch brite pad based on a tip. 

Overall I am close to being finished. The mahogany sure did suck up the poly. I have found that wipe on Poly (at least the stuff I bought from Minwax) is so thin that two coats are needed to cover up a final scuff sand. A first application of wipe on (per the thread from JJRBUS) for maximum penetration, followed by one or two brush on coats, followed by two wipe on coats seems to be the way to go for a straightforward poly finish.

Will post pictures as I finish up over the next week.

Thanks,
Brian


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## tc65 (Jan 9, 2012)

monty - just a tip for the future. The poly sold in containers as wipe on poly is the same as the brush on poly, only it's already thinned down and more expensive. 

You can take the brush on poly, thin with mineral spirits and make your own to your desired consistency. Mix it in a separate container and thin until you get a thickness that works for you. Be sure to measure the volume of each so you'll know in the future how much to use.


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## jjrbus (Dec 6, 2009)

Sorry to hear it is over your head. It really simplified things for me. Different strokes I guess.

JIm


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## GAF (Nov 4, 2012)

Fred Hargis said:


> That certainly doesn't seem like enough coats to me as well. I normally consider 3 coats of wiping varnish equal to about 1 coat brushed on. I typically apply it in sets of 3, let it dry overnight, then 3 more and so on. With wiping varnish, scuffing between coats of a set isn't really needed. But between sets (if it's a urethane product) is a good thing.


Fred, it would be very helpful to me if you could elaborate on your comments about applying wiping varnish in sets of 3.

I use home-made wipe on poly (MinWax Poly diluted 50% with mineral spirits) all the time. But I sand and rub down with denatured alcohol between each coat. Since I put a minimum of 6 coats on a piece this takes me quite a long time. The MinWax web site would suggest that what I am doing is required for each coat.

If I could eliminate some steps this would be terrific. Do you do a set of 3 coats in one day? Drying would be an issue in my mind.

Any feedback would be appreciated. Thanks.

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Fred, it would be very helpful to me if you could elaborate on your comments about applying wiping varnish in sets of 3.
> 
> I use home-made wipe on poly (MinWax Poly diluted 50% with mineral spirits) all the time. But I sand and rub down with denatured alcohol between each coat. Since I put a minimum of 6 coats on a piece this takes me quite a long time. The MinWax web site would suggest that what I am doing is required for each coat.
> 
> ...


Hey Gary, the way I read it is you start off on day one and wipe on three coats. Then on day two you sand the finish with 220 or finer paper and do three more coats. Then if the finish isn't thick enough on day three you sand it and do three more coats. You only sand it at the beginning when the finish is hard enough to withstand sanding and not gum up on the paper. He left out the drying time between the wipe on coats but it's probably about 2 1/2 hours in warm weather so you could do three coats in a eight hour day.


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## GAF (Nov 4, 2012)

Steve Neul said:


> Hey Gary, the way I read it is you start off on day one and wipe on three coats. Then on day two you sand the finish with 220 or finer paper and do three more coats. Then if the finish isn't thick enough on day three you sand it and do three more coats. You only sand it at the beginning when the finish is hard enough to withstand sanding and not gum up on the paper. He left out the drying time between the wipe on coats but it's probably about 2 1/2 hours in warm weather so you could do three coats in a eight hour day.


Steve some good feedback and interpretation. I am still hoping Fred will comment because most of what I have read says that sanding between each coat is required. I really would like to understand his logic for not having to do that.

I suspect you use lacquer most of the time which of course eliminates the sanding step. I don't have any spray capability or good brushing skills. I have never been able to find anything about wiping on lacquer.

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Steve some good feedback and interpretation. I am still hoping Fred will comment because most of what I have read says that sanding between each coat is required. I really would like to understand his logic for not having to do that.
> 
> I suspect you use lacquer most of the time which of course eliminates the sanding step. I don't have any spray capability or good brushing skills. I have never been able to find anything about wiping on lacquer.
> 
> Gary


I think it would work to omit the sanding step because at that stage the finish wouldn't be hard yet and it would bond chemically. 

I think you need to get the equipment to spray. Once you do you will wonder how in the H you ever lived without it. Even using oil based poly is easier sprayed.


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## cps (Jun 21, 2013)

GAF said:


> Steve some good feedback and interpretation. I am still hoping Fred will comment because most of what I have read says that sanding between each coat is required. I really would like to understand his logic for not having to do that.
> 
> I suspect you use lacquer most of the time which of course eliminates the sanding step. I don't have any spray capability or good brushing skills. I have never been able to find anything about wiping on lacquer.
> 
> Gary


This article describes how to wipe on coats without sanding....


http://www.hardwoodlumberandmore.co...age/tabid/75/ArticleId/5/Wipe-on-Varnish.aspx


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## Steve Neul (Sep 2, 2011)

cps said:


> This article describes how to wipe on coats without sanding....
> 
> 
> http://www.hardwoodlumberandmore.co...age/tabid/75/ArticleId/5/Wipe-on-Varnish.aspx


 It was a nice article but it was about wiping varnish which adheres a great deal better than wiping polyurethane. Polyurethane you have to work at it more for it to adhere.


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## cps (Jun 21, 2013)

Steve Neul said:


> It was a nice article but it was about wiping varnish which adheres a great deal better than wiping polyurethane. Polyurethane you have to work at it more for it to adhere.


I always thought Polyurethane was short for Polyurethane Varnish....


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## Steve Neul (Sep 2, 2011)

cps said:


> I always thought Polyurethane was short for Polyurethane Varnish....


They do some funny things with wording on products that keep everyone confused. A varnish is made from pine resins where polyurethane is made with urethane resins which makes it more of a plastic than a varnish but both have linseed oil in them and are similar and I've seen cans labeled polyurethane varnish but they are different finishes. 

I inherited a oak table from an aunt that probably had 30 coats of varnish on it which were adhered very well. and I know she didn't know anything about finishing or did any between the coats sanding. Every few years when the finish got to looking bad she would drag the table out on her back porch and put a coat of varnish on it. She had the table from 1900 to about 1975 so the table got a lot of coats.


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## cps (Jun 21, 2013)

Steve Neul said:


> They do some funny things with wording on products that keep everyone confused. A varnish is made from pine resins where polyurethane is made with urethane resins which makes it more of a plastic than a varnish but both have linseed oil in them and are similar and I've seen cans labeled polyurethane varnish but they are different finishes.
> 
> I inherited a oak table from an aunt that probably had 30 coats of varnish on it which were adhered very well. and I know she didn't know anything about finishing or did any between the coats sanding. Every few years when the finish got to looking bad she would drag the table out on her back porch and put a coat of varnish on it. She had the table from 1900 to about 1975 so the table got a lot of coats.


 
It seems some use the word varnish more generically:

“What is Wiping Varnish?
Wiping varnish is simply common oil-based varnish (any type, including alkyd varnish, *polyurethane varnish* or spar varnish) that is thinned enough with mineral spirits (paint thinner) so it is easy to wipe on wood. You can easily make your own.”

From
http://www.popularwoodworking.com/techniques/finishing/the_basics_of_wiping_varnish2


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## jjrbus (Dec 6, 2009)

There is a bit of misdirection in the retail finishing products industry!

http://www.popularwoodworking.com/techniques/finishing/oil-finishes-their-history-and-use
HTH JIm


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## Steve Neul (Sep 2, 2011)

cps said:


> It seems some use the word varnish more generically:
> 
> “What is Wiping Varnish?
> Wiping varnish is simply common oil-based varnish (any type, including alkyd varnish, *polyurethane varnish* or spar varnish) that is thinned enough with mineral spirits (paint thinner) so it is easy to wipe on wood. You can easily make your own.”
> ...


 Yea, I hate it. I don't want to be a chemist with this stuff. I'm more concerned with the application of these products then what is in it. I wish they would give them completely different names. I think it would be simpler for everyone.


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## GAF (Nov 4, 2012)

Steve Neul said:


> I think it would work to omit the sanding step because at that stage the finish wouldn't be hard yet and it would bond chemically.
> 
> I think you need to get the equipment to spray. Once you do you will wonder how in the H you ever lived without it. Even using oil based poly is easier sprayed.


 
Steve in all the research that I have done never have I seen an explanation that polyurethane would bond chemically. For lacquer and shellac I have read that but not poly. Maybe the freshness of the top coat (doing 3 in one day) would make that difference.

No doubt spraying is the way to go but as a hobbyist I am not sure that I will ever get there.

Gary


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## GAF (Nov 4, 2012)

Steve Neul said:


> Yea, I hate it. I don't want to be a chemist with this stuff. I'm more concerned with the application of these products then what is in it. I wish they would give them completely different names. I think it would be simpler for everyone.


 
Based on the comments from the other guys as well now I am confused all over again. Ugh.

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Steve in all the research that I have done never have I seen an explanation that polyurethane would bond chemically. For lacquer and shellac I have read that but not poly. Maybe the freshness of the top coat (doing 3 in one day) would make that difference.
> 
> No doubt spraying is the way to go but as a hobbyist I am not sure that I will ever get there.
> 
> Gary


The way I understand it once the poly is applied the solvents start escaping and the other chemicals react together and the molecules get tighter and tighter until it hardens. Doing three coats in one day while it is in the process of hardening I believe it would allow it to bond before it completely hardens. It's the hardness of polyurethane that requires the mechanical bonding. A alkyd varnish is very similar but you could use it like an oil based paint without sanding. In the old days when they used oil based paint on the exterior woodwork on a house, nobody sanded between coats. 

Personally I don't wipe poly so I would rely on Freds experience. I either brush or spray it. Brushing it I would never attempt to put another coat on before it drys because the finish is thicker and would still be wet under the surface. 

Could I ask you why you are apprehensive on spraying finishes?


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## Steve Neul (Sep 2, 2011)

GAF said:


> Based on the comments from the other guys as well now I am confused all over again. Ugh.
> 
> Gary


Welcome to the club. It's just best to pick as few different products that will work for you and stick with it. I've never been fond of trying new products for that reason. I even saw something the other day I need to read more about it that water based polyurethane isn't polyurethane at all, that it's a completely different chemical they stuck the word polyurethane on it to compete with oil based polyurethane.


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## GAF (Nov 4, 2012)

Steve Neul said:


> The way I understand it once the poly is applied the solvents start escaping and the other chemicals react together and the molecules get tighter and tighter until it hardens. Doing three coats in one day while it is in the process of hardening I believe it would allow it to bond before it completely hardens. It's the hardness of polyurethane that requires the mechanical bonding. A alkyd varnish is very similar but you could use it like an oil based paint without sanding. In the old days when they used oil based paint on the exterior woodwork on a house, nobody sanded between coats.
> 
> Personally I don't wipe poly so I would rely on Freds experience. I either brush or spray it. Brushing it I would never attempt to put another coat on before it drys because the finish is thicker and would still be wet under the surface.
> 
> Could I ask you why you are apprehensive on spraying finishes?


Steve my main reluctance about spraying is simply not having set up a facility in which to do it. I would expect such a set up would not be simple to create.

Gary


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## Steve Neul (Sep 2, 2011)

GAF said:


> Steve my main reluctance about spraying is simply not having set up a facility in which to do it. I would expect such a set up would not be simple to create.
> 
> Gary


 Of course polyurethane would be better done with better facilities but I'm essentually finishing outdoors under an awning. At one time I had a finishing shop but I had a storm destroy my main shop and I had to move the finishing out and move my woodworking equipment into my finishing shop. When I work with polyurethane I just spray it inside the building at the end of the day and leave. There is dust and dirt all over the walls and ceiling but I still don't get any in the finish. Most of the time when you get dirt in the finish the dirt comes off the painter rather than the building. 

It wouldn't be to difficult to build a spray room for small work. A building the size of a storage building would work. The building would just need an exhaust fan which could be made from a furnace blower that didn't have a motor in the center of it and a panel on the other side with furnace filters in it to clean the incomming air.


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## GAF (Nov 4, 2012)

Steve Neul said:


> Of course polyurethane would be better done with better facilities but I'm essentually finishing outdoors under an awning. At one time I had a finishing shop but I had a storm destroy my main shop and I had to move the finishing out and move my woodworking equipment into my finishing shop. When I work with polyurethane I just spray it inside the building at the end of the day and leave. There is dust and dirt all over the walls and ceiling but I still don't get any in the finish. Most of the time when you get dirt in the finish the dirt comes off the painter rather than the building.
> 
> It wouldn't be to difficult to build a spray room for small work. A building the size of a storage building would work. The building would just need an exhaust fan which could be made from a furnace blower that didn't have a motor in the center of it and a panel on the other side with furnace filters in it to clean the incomming air.


Steve there are lots of enticing suggestions in your comments above. This fall I am building a separate 10 foot square sanding room in an effort to keep the sawdust contained in one area of my large garage. Maybe a spay booth will be the next project.

Gary


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## Mountain (Aug 1, 2013)

I am currently doing a table that I want a deep poly finish on, does anyone have a link to a reasonable sprayer?

I have paint sprayers designed for automotive painting, not sure I would want to run poly through either of them and not sure if it would even work anyway.


Ok, I just did some searching and found this.... http://www.meijer.com/s/homeright-hvlp-paint-sprayer/_/R-208158

I got the impression that the op would never be willing to put out the money for the spray setup, I could very well be wrong on that just my guess. The price of this one is $90 and they seem to have some cheaper ones as well. I am not thrilled with the made in Taiwan, but I haven't even been able to find an American made one yet.


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## jjrbus (Dec 6, 2009)

I try to keep an open mind and took a look at the Homeright sprayer. Some new products come out that can be superior. The reviews on this are mixed from 5 star wonderful to 1 star junk! Not something I would spend my $90 on.

It appears to be very similar to the Wagner, if I wanted a Wagner I would buy it at a garage sale for $10!

Just my personal opinion

I am considering the purchase of a Wagner conversion gun. This is a completely different animal and requires a compressor. 

http://www.wagnerspraytech.com/portal/hvlpconversiongun_en_spray,496884,358970.html

It is more money ($150), but has great reviews and a paint pot can be added for large jobs.


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## Steve Neul (Sep 2, 2011)

Mountain said:


> I am currently doing a table that I want a deep poly finish on, does anyone have a link to a reasonable sprayer?
> 
> I have paint sprayers designed for automotive painting, not sure I would want to run poly through either of them and not sure if it would even work anyway.
> 
> ...


I do some automotive painting, some kitchen cabinets, some furniture refinishing and I use a harbor freight sprayer #97855 I get for 20 bucks with a coupon. This tractor was painted with a 2k urethane paint, stenciling and all with it.


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## cabinetman (Jul 5, 2007)

Mountain said:


> I have paint sprayers designed for automotive painting, not sure I would want to run poly through either of them and not sure if it would even work anyway.


Guns used for automotive spraying can spray wood finish topcoats.








 







.


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