Wipe-On Polyurethane Confusion

[JP_Crafting]

So I've been working with Watco satin Wipe-On Oil Polyurethane. I first pour the poly into a resealable cup and stir it up. Then I get either cut up white tee shirt pieces, or some strips of cloth that you can get from Home Depot for this kind of thing. I then wipe on a little poly and buff it while it's still wet. I usually lightly sand with 220# sandpaper before the last coat. 

I'm probably not supposed to buff the poly right after I apply it, but every way I've tried to apply the stuff I get bad results. If I apply poly without buffing I get either shiny and flat spots or settling-dust bumps. Buffing it is the only way I've been able to minimize these things. I've heard of people getting amazing results from wipe-on poly. Why can't I? Am I using the wrong rags? Am I not putting enough on per coat, or too little? Am I not stirring the solution enough? 


(This is an example of a shiny spot. I know for sure these are not from accidentally touching the tacky poly or anything.)

Thank y'all,

Jp

[jteneyck]

You need to stir it really, really well to get the flatters uniformly distributed before using it, every time you use it. I think your shiny spots are because the flatters aren't uniformly distributed.

Then try using a blue shop paper towel to apply it instead of cloth. For narrow parts a single sheet of paper towel is large enough.  Just fold it so you have a flat surface, dip it in the finish so it's saturated but not dripping and then wipe it on.  Try it on scrap until you can get it on uniformly.  It should look uniformly wet, but very thin.  Don't polish it off, just leave it to dry.

For large surfaces wad up a paper towel or piece of cotton cloth put it inside of another paper towel.  Gather the ends of the paper towel so that you have a nice smooth ball on the front.  Dip that into the finish and then wipe it onto your part, making full swipes from one end to the other if possible.  Reload and do the next stripe, overlapping just a little.  It takes practice to do it well, but you can make it somewhat easier by thinning the finish 10 - 20% with mineral spirits, if it's drying so quickly that the paper towel starts to drag.  

I sometimes apply the first couple of coats on large surfaces using a foam brush and thinning the finish.  Then I sand it smooth and apply the last couple of coats with the paper towel.  

There's no right way except for the one that works best for you.  Some folks have good results applying it like a busboy cleans tables.  Never worked for me, but thought I'd mention it.  And if the only way that works for you is by buffing it, have at it; it's just going to take a lot more coats.  

John

[fredhargis]

It sounds like you aren't stirring the who;e can, just what's in your cup. In the can the flatters settle to the bottom, and what you pour out is gloss varnish. I think you need to mix the whole can thoroughly, then pour out what you need and keep it mixed. That said, that shiny spot has such a distinct shape It's hard (for me) to imagine how improperly stirred finish would cause that. Is that just the first coat, or is this after several coats?

[Bill Wilson]

This is something I saved years ago, contributed by a fellow who was considered something of a finishing guru on this forum, back in the day.  I don't use wiping varnish much myself, so I can't add anything, but I hope this helps;

Supplement to wiping varnish, courtesy of Howard Acheson/Jim Kull
 
There are a number of suggested application regimens that are totally subjective. The number of coats in a given day, the % of cut on various coats, which coat to sand after, when to use the blade and a whole host of other practices are all minor differences between finishers. There are some things that I consider sacred when applying a wipe-on finish.

If you are making your own wipe-on the mix is scientific - thin. I suggest 50/50 with mineral spirits because it is easier to type than any other ratio and easy to remember.

The number of coats in a given day is not important. Important is to apply a wet coat with an applicator and merely get it on. Think of a 16 year old kid working as a busboy at Denny's you have sent over to wipe off a table. The applicator should be wet but not soaked. The applicator can be a paper towel, half a T-shirt sleeve or that one sock left after a load of washing. Then leave it alone. The surface should not be glossy or wet looking. If you have missed a spot, ignore it - you will get it on the next coat. If you try and fix a missed spot you will leave a mark in the finish.

Timing for a second coat involves the pinkie test. Touch the surface with your pinkie. If nothing comes off you are ready for another coat. It was tacky 5 minutes ago but not now. Apply your next coat just as you applied the previous coat. Remember, you are wet wiping not flooding. After applying the second coat, let it fully dry for 48 hours. Using 320 paper and a sanding block ligthtly sand the surface flat. Now, begin applying more coats. Do not sand between coats unless you have allowed more than 24 hours to elapse since the prior coat. Keep going till you are tired of it. The number of coats is not critical - there is no critical or right number to apply. For those who need a rule, two to four more coats on non-critical surfaces or six more coats on surfaces that will get abraded seems to work.

After your last coat has dried at least over night you will have boogers in the surface. You should not have marks in the surface because you ignored application flaws. You may have dust, lint and, if you live in Texas, bug legs. Use a utility knife blade at this point. Hold it between your thumb and forefinger, near the vertical, and gently scrape the surface. Gentle is the important word - no harder than you would scrape your face. If you start scraping aggressively you will leave small cut marks in the surface. After you have scraped to the baby butt stage gently abrade the surface with 320 dry paper or a gray ScotchBrite. Clean off the surface. Now, leave the area for two hours and change your clothes. Apply your last coat with a bit more care than the previous coats and walk away.

An anal person is going to have a tough time with this process. Missed spots have to be ignored. Wet wipe, don't flood. Scraping to babies butt smooth means scraping no harder than scraping a babies butt. Ignoring any of these will leave marks that are tough to get out. Getting these marks out requires some agressive sanding to flatten out the surface and starting over.

Jim Kull

END QUOTE

Finally, It works better to use a gloss varnish for all coats except the last. The flatteners in semi-gloss and satin tend to rapidly fall out of suspension when the finish is highly thinned. If you want a non-gloss finish, use it only on the final coat or two and be sure to stir the material frequently or you will end up with cloudy streaks.

Let the whole thing dry a few weeks indoors and then apply a coat of furniture paste wax using a gray scotchbrite pad. Keep wet glasses off it for 3-4 months. You should use coasters anyway.

[Rob Young]

Yep, mix the full can as the flatteners settle to the bottom.

If you are buying the WIP, directions are on the can and usually are the place to start. I think John's answer and the quote above have the gist of it. Flood on the first coat, let it sit just a bit and wipe down. Check it again a bit later, say 20 minutes and maybe wipe again (open grain woods might have some finish coming back up out of the pores). Let dry sufficiently that it won't clog a fine grit (word of the day is "corning"). Sand and repeat.

Foam brushes are great for this stuff and you can practice your technique for "tipping off". If you buy a bag of rags from anywhere, wash them first, even if they say "lint free". They aren't.

Just practice some more.

[Cooler]

Or you can use gloss and then use steel wool (0000) to knock down the shine.  No flatteners involved.

The advantage is that the mica flakes used to flatten the shine also obscure the wood.  So the more coats you add the less you see the wood grain.  With the gloss, it is all clear until you add the rub down with steel wool.

I brush on poly, and I use the steel wool on that.  I rarely use wipe on (I did for some walking sticks, but I left them glossy).

[CLETUS]

Too much finish in that spot.

[jteneyck]

Too much finish in that spot.

Or maybe a glue spot or tape residue?  

john

[jteneyck]

Or you can use gloss and then use steel wool (0000) to knock down the shine.  No flatteners involved.

The advantage is that the mica flakes used to flatten the shine also obscure the wood.  So the more coats you add the less you see the wood grain.  With the gloss, it is all clear until you add the rub down with steel wool.

I brush on poly, and I use the steel wool on that.  I rarely use wipe on (I did for some walking sticks, but I left them glossy).

Cooler, the flatters are colloidal silica, not mica. 

John

[jteneyck]

Yep, mix the full can as the flatteners settle to the bottom.

If you are buying the WIP, directions are on the can and usually are the place to start.  I think John's answer and the quote above have the gist of it. Flood on the first coat, let it sit just a bit and wipe down. Check it again a bit later, say 20 minutes and maybe wipe again (open grain woods might have some finish coming back up out of the pores). Let dry sufficiently that it won't clog a fine grit (word of the day is "corning"). Sand and repeat.

Foam brushes are great for this stuff and you can practice your technique for "tipping off". If you buy a bag of rags from anywhere, wash them first, even if they say "lint free". They aren't.

Just practice some more.

I know it sounds strange, and I didn't believe it until I looked it up, but the correct word is "flatters".  Seems like it should be flatteners, but it's not.  Of course, everyone still knows what you mean, and most probably think it's the correct term.  

John