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Wipe-On Polyurethane Confusion

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Forum topic by JP_Crafting posted 03-22-2019 01:06 AM 339 views 0 times favorited 10 replies Add to Favorites Watch
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JP_Crafting

3 posts in 33 days


03-22-2019 01:06 AM

Topic tags/keywords: polyurethane poly watco

So I’ve been finishing a few projects using Watco’s Satin Wipe-On Poly. It is the oil based variety. I use either cut up old white tee shirts, or some cloth from the bag of cloth Home Depot sells. I pour some poly into a little cup and stir it up. I then wipe on the poly in the direction of the grain with the cloth. I then go back and buff it with the dryer side of the cloth. Most of the time I lightly sand with 220# sandpaper before the last coat. I make sure to seal the cup of poly between uses.

I find that no matter how I apply the poly, I either get weird shiny and flat spots, or settling dust bulbs in the wood. I’ve used a variety of wood species, so I know it’s not that. I also think that I’m not supposed to buff out the wet finish right after I apply it, but either way, I get undesirable results. There’s not much online about how to apply it. How thick of a coat do I apply? Am I not stirring up the solution enough? Is my cloth wrong? Is poly just a pain in the butt to apply? Is Danish Oil easier/better?

(This image is an example of a shiny spot under the light. The spot is not caused by my fingerprint on the wet poly.)

Thank y’all,

Jp


10 replies so far

View bilyo's profile

bilyo

611 posts in 1435 days


#1 posted 03-22-2019 01:22 AM

If I understand your post correctly, you are wiping on the poly and then wiping off the excess as you would with danish oil. This is not the correct process with wipe-on poly. With poly: first stir the whole can, not just the cup you are using. The idea is to mix up all the flattening agent in the bottom of the can (assuming you are using satin or semi-gloss). To apply, spread a thin coat (think wiping your kitchen counter with a barely damp cloth). Then, let it dry. Do not wipe it further with a dry cloth as you would if you were using oil. Let the finish build thickness with 2-3 coats before you do any sanding between coats. I don’t usually do any sanding until I’m ready for the final coat and then I will lightly sand with at least 220 or finer. After the final coat, I may sand using water with 600 grit wet/dry sandpaper. Then wax.

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Madmark2

447 posts in 920 days


#2 posted 03-22-2019 01:26 AM

Are you mixing the whole can before pouring off the top into your cup and stirring?

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MikeDilday

192 posts in 791 days


#3 posted 03-22-2019 01:36 AM

Don’t press down too hard. Just very gentle pressure to spread the poly.

Don’t over-wipe it.

Use slow, long strokes overlapping the last stroke. If you start a stroke or end a stroke mid-board as you are moving the cloth ease it onto the wood and lift it off like an airplane landing and taking off. This will help avoid puddles.

Always be on the lookout for puddles and runs as you go.

Plan your job into sections. After a few minutes you can’t go back and wipe over again. Poly skins over fast and it will not dry smooth.

And like above stir the entire can and don’t wipe it off. Takes a few hours to dry for another coat.

You can use fine (0000) steel wool instead of 220 sandpaper before the last coat.

Make sure before the first coat and after sanding before final coat you remove all dust. A soft brush attached to a vacuum or a cotton rag with mineral spirits is a good way to remove all dust. This is especially important before the final coat.

Try to avoid dust in the shop as you poly.

You will have a great finish.

Good luck.

-- Michael Dilday, Suffolk, Va.

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JP_Crafting

3 posts in 33 days


#4 posted 03-22-2019 01:50 AM

Okay, so stirring the can is a must! This is all important to know. It seems that getting a glossy poly without flatters would be much less of a hassle. But how would I prevent pools, deal with accidentally putting on a coat that’s too thick, and apply the finish to very thin and intricate projects?

P.S. Is danish oil just far easier to apply? I haven’t worked with it before.

Thanks,
Jp

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MikeDilday

192 posts in 791 days


#5 posted 03-22-2019 01:56 AM

Stir, don’t shake. You don’t want bubbles in the poly. Stirring is not much of a hassle – I would stir glossy poly too just to make sure the chemicals are mixed good. If you rub it out that will eliminate pools. I cut a piece of old t-shirt about 3-4” square. I dip one corner in the poly about one-third of the cloth. Depending on how big an area I have to do I may squeeze a little out. You want the coat to be thin – not like painting. Several thin coats is what you need. Don’t over think it.

-- Michael Dilday, Suffolk, Va.

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MikeDilday

192 posts in 791 days


#6 posted 03-22-2019 01:57 AM

You may be using too big of a piece of cloth and that will complicate things.

-- Michael Dilday, Suffolk, Va.

View MrUnix's profile

MrUnix

7313 posts in 2531 days


#7 posted 03-22-2019 03:17 AM

Don’t over complicate things! To me, wipe on poly is about as easy and foolproof as it gets. The only caveat is I mix my own poly (50/50 oil based poly to mineral spirits) instead of paying the manufacturer to mix it for me. Have long forgot where I heard this method described, but it works perfectly every time and is easy to remember:

Consider some pimple faced teenage kid working nights at the local Denny’s restaurant on a Saturday night wiping down tables- he would rather be anywhere but there, and just wants to get it over with so he can get out and party with his friends. The soaked rag is plopped down on the table and swirled around in no particular order, just making sure that every part of the table top gets good and wet. Back and forth, zig-zags, circles, whatever – just make sure every inch of the table top is touched. Then the rag is rung out and used to remove all the excess left on the table top – to the point where it is just barely wet with a very thin film left remaining – one that will quickly evaporate so the next ‘customer’ can use the table almost immediately.

That is exactly the method I use – but with poly :) Slap it on, wipe it thin and let dry – The thin film initially on bare wood will dry to the touch within 5-10 minutes or even sooner. As soon as it’s dry to the touch, slap down another coat. 10-15 minutes later, it will be dry do the touch, so slap down another. No need to sand between coats [1] – and don’t worry about dust nibs or imperfections. Resist the urge to go back and ‘touch up’ a coat – just let it dry to the touch and then address any problems with the next coat.

I usually put down at least 3-6 coats before letting is sit over night to cure. The next morning (or any time after that), hit it with a very light sanding to remove any dust or remaining imperfections, and either put a final wipe on coat, or keep cycling like before until you have reached your desired film thickness/look.

The key is to use THIN coats – as thin as possible, and use lots of them. 3-4 wipe on coats will roughly equal one brushed on coat. Yes, you have to put down a lot more – but the upside is you will never get brush strokes, drips or runs ever again… and you can make the finish look like anything from no finish at all to a very high build/gloss and anything in between.

Cheers,
Brad

[1] No need to sand between coats as long as the poly has not cured… which generally takes anywhere from about 12-24 hours. Remember: Dry to the touch does not mean cured!

PS: As others have mentioned, if you are using anything other than gloss poly, you need to stir the can before pouring it out. It also helps to use gloss for all coats up to the final coat, and then using whatever final coat finish you want if not gloss. Non-gloss poly has flattening agents that alter the clarity of the poly, so using gloss will retain the transparency up to the final finish coat. Using a non-clear for all coats will produce a more opaque finish.

-- Brad in FL - In Dog I trust... everything else is questionable

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SMP

619 posts in 238 days


#8 posted 03-22-2019 04:19 AM

I know you aren’t using the General Finishes but i found the instructions here on how to apply very helpful. Also, try Arm r Seal when you get a chance i find it much more forgiving.

https://generalfinishes.com/wood-finishes-retail/oil-based-topcoats/arm-r-seal-oil-based-topcoat

View EarlS's profile

EarlS

2661 posts in 2680 days


#9 posted 03-22-2019 11:45 AM

SMP +1

Arm-R-Seal gives a much better finish than than wipe on poly.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

View OSU55's profile

OSU55

2209 posts in 2322 days


#10 posted 03-22-2019 12:25 PM

Yep, stir the can if other than gloss. It can be shaken (1 of the myths) but the flatting agent can be difficult to get off the bottom. Scraping the botton ensures all the agent gets picked up and mixed in.

Wiping varnish, thinned poly, can be applied just like danish oil. I use a combination of danish oil method and Brad’s wipe off a table method. The 1st 2 coats, flood the surface, keep wet for ~ 5-10 min, till the wood stops soaking it up, wipe off, after 30-60 min or longer repeat (give time for solvents to flash). Can leave a thin film. Now just follow Brad’s method. I find saturating the surface with 2 coats keeps from having dry spots and builds those areas faster.

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