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Water-based poly. I'm sure I'm doing it wrong.

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Forum topic by Ocelot posted 02-21-2014 09:34 PM 1091 views 0 times favorited 28 replies Add to Favorites Watch
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Ocelot

589 posts in 1291 days


02-21-2014 09:34 PM

This has been my first try at water-based finishes and I’m not too happy about it.

I’m finishing a poplar bookcase with 8 shelves about 5’ wide.

It was well sanded (to 320) before I started. After the first coat of water-based poly, the surface was very rough as a result of raised grain. I sanded (with 220, by hand, on a rubber sanding block) for about 5 hours to put it right – and wondered if there was any poly left on the thing after that. The second coat seems to raise the grain too – just not as much. I figure at this rate, I’ll be into the 4th coat before it stops raising the grain.

I’m sure I’m doing it wrong. This is miserable!

Can anyone straighten me out. The product is “Rust-Oleum Ultimate semi-gloss Polyurethane”.

-Ocelot


28 replies so far

View Fred Hargis's profile

Fred Hargis

1783 posts in 1146 days


#1 posted 02-21-2014 09:47 PM

A lot of folks seal the wood with shellac before using a waterborne finish to prevent that. You could do that, or just go ahead and apply your 3rd coat without worrying about it….then smooth it out. Eventually you get to a point where the whiskers are locked in by the finish and won’t raise anymore….I suspect you might be there now. In any case, after the third coat (or however many you come to accept as the right number) sand it smooth, apply your last coat and your done.

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

View bigblockyeti's profile

bigblockyeti

1545 posts in 373 days


#2 posted 02-21-2014 09:51 PM

Did you by chance try to raise the grain before starting? I usually do that twice even when using oil, cheap insurance.

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Ocelot

589 posts in 1291 days


#3 posted 02-21-2014 09:56 PM

Thanks for your replies.

I read something about using shellac on LJ, but did not try it. The reason I’m using water-based finish is that it had been too cold in the shop, so I’m finishing in the house while my wife is newly pregnant and sensitive to odors. I’ve never used shellac and didn’t know how odiferous it is. Does shellac smell?

No, I didn’t raise the grain before starting. I’ve always used traditional finishes and never had an issue – although I’m a very low-volume wood-worker.

-Ocelot

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pintodeluxe

3359 posts in 1466 days


#4 posted 02-21-2014 10:57 PM

Shellac has a distinctive odor, some people like it and some hate it. Kind of like the smell of Simple Green that way.

With anything water based like dyes or finishes, I like to raise the grain before finishing. Then you can scuff sand with some 320 grit before you apply the finish. This way your stain or topcoat won’t be sanded away.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Rick's profile

Rick

6454 posts in 1686 days


#5 posted 02-21-2014 11:52 PM

You didn’t “Shake” the container before applying it did you? Water Based Poly MUST always be Stirred or else you end up trying to apply a “Vanilla Milkshake” ...LOL.. (Full Of Bubbles.) Usually tells you that on the can. Flecto or Minwax Poly at any rate.

I use Water Based Poly all the time, also on Poplar, never had this happen. Three coats always does it just fine. I’ve never Pre-Raised the grain.

I use to use WHITE Shellac thinned with Methyl Hydrate to seal any kind of wood. Dries almost instantly.

The water based Poly they have out now, in my opinion dries Way To Fast. You have to put it on reasonably thickly, quickly brush it out and Leave It Alone.

-- COMMON SENSE Is Like Deodorant. The People Who need It Most, Never Use It.

View PineChopper's profile

PineChopper

175 posts in 849 days


#6 posted 02-22-2014 12:34 AM

I’ve never had that kind of a problem with the water based poly. Sounds like you might be over sanding in between coats.

View The Box Whisperer's profile (online now)

The Box Whisperer

582 posts in 723 days


#7 posted 02-22-2014 12:52 AM

keep sanding or dont bother untill your next coat, in my experience the 3rd, thin coat is where it all starts to come together with waterpoly.

-- "despite you best efforts and your confidence that your smarter and faster than a saw blade at 10k rpm…. your not …." - Charles Neil

View Clint Searl's profile

Clint Searl

1450 posts in 1014 days


#8 posted 02-22-2014 01:21 AM

Forget shellac. WB poly does fine if you just knock down the first coat nibs with 220 drywall sanding screen, followed by a couple more full wet coats.

Note: Never sand past 220 before finishing.

-- Clint Searl....Ya can no more do what ya don't know how than ya can git back from where ya ain't been

View a1Jim's profile

a1Jim

112083 posts in 2230 days


#9 posted 02-22-2014 01:27 AM

IMO there’s no reason to sand the wood to 320,150-180 is fine .As others have said you can raise the grain first then do a light sanding with 220 grit, don’t over do it just a quick once over or you will raise the grain over and over again. apply your coat (spray if you can) thinned 10% let dry usually 2 hours then another light sanding 320 grit ,apply second coat(spray if you can) unthinned let dry,if you still have raised grain do another very light sanding with 600 grit or higher grit after that it’s up to you and the type of gloss you want whether you do a third coat.

-- http://artisticwoodstudio.com Custom furniture

View Rick's profile

Rick

6454 posts in 1686 days


#10 posted 02-22-2014 01:52 AM

Sorry Double Post.

-- COMMON SENSE Is Like Deodorant. The People Who need It Most, Never Use It.

View NormG's profile

NormG

4175 posts in 1657 days


#11 posted 02-22-2014 01:58 AM

Sounds like a1Jim has a great idea

-- Norman

View rg33's profile

rg33

51 posts in 655 days


#12 posted 02-22-2014 02:14 AM

I cant recall the last time I used something other than water based poly (as my skills get better I do want to get into the more traditional finishes) but have always had good results. I think you’re main issue is that you likely sanded too much after the first coat. Again only from personal experience i’ve never had to raise the grain beforehand. Here is what I do and works for me:
1. Finish sand with 220. I’ver never needed to use finer
2 Stain with oil based stain and allow for a full dry 24 hrs+(i never thought about this until now but maybe this has helped to condition the wood)
3 As others have said stir DO NOT SHAKE poly.
4 Apply first coat and let dry. At this point finish will look and feel rough.
5 Take 220 sandpaper, and lightly pass over surface. To give you an idea of how much, I spend about 5 minutes on the top surface the size of a desk. All you want is to knock down the peaks really. Poly looks white after you sand but do not fear, you’re done when you can pass your hand on the surface and no longer feels rough, even if it doesnt look perfect because the next coat will cover the tiny scratches that are only poly deep. make sure to wipe pretty well
6 Put another coat and let dry. By this point the surface will be well sealed. I rarely sand at this point.
7Finish with third coat.

hope this helps

View SuperCubber's profile

SuperCubber

276 posts in 937 days


#13 posted 02-22-2014 05:36 AM

I do almost the exact same process as rg33, except step 5 is slightly different. I use 320 instead of 220, and I do one or two VERY light passes. Like he said, just enough to knock down the nibs. I don’t even put any pressure on the block. I let the weight of the block do the work. After that I wipe it down with a damp rag before the next coat.

Also, I usually do a quick sanding with 320 between subsequent coats, but I’m not sure that’s completely necessary.

*The process I use applies to both spraying and brushing.

View Ocelot's profile

Ocelot

589 posts in 1291 days


#14 posted 02-22-2014 01:42 PM

Wow! Lots of replies.

I’ll try to respond.

First, I stirred. No shaking. I’m pretty good at following directions!

2nd. I wanted a natural, very light finish, so there was no stain or other finish prior to the poly. That may be a big difference from what some of you folks (supercubber and rg33) are doing.

I could feel the grain rising while I was brushing it on – could feel the wood become rough under the brush.

Oh, in case it matters, I was/am using a foam brush.

I’ve never before sanded after applying finish. I could not see any alternative this time since the surface, which had been glassy smooth became quite rough while applying the 1st coat.

So, from what rg33 says, it is normal for the surface to be rough? This is a big surprise to me. I had no idea. Do later coats fill in the roughness and make it smooth again?

-Ocelot

View SuperCubber's profile

SuperCubber

276 posts in 937 days


#15 posted 02-22-2014 04:57 PM

Ocelot,

I have never used water-based over a stain. I’ve used it straight, and over a water-based dye. It is perfectly normal for it to be rough. I would not expect the poly to fill in the roughness. Lightly sand with 320, apply another coat and let us know how it feels.

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