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Water-based polyurethanes

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Forum topic by William Shelley posted 01-13-2018 05:51 AM 514 views 0 times favorited 4 replies Add to Favorites Watch
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William Shelley

576 posts in 1591 days


01-13-2018 05:51 AM

Hi all,

Due to the winter temps, I can’t ventilate my shop much unless I want to freeze to death, so I’m forced to use waterborne polyurethane instead of oil-based. I’m spraying Radiata pine plywood, with a Husky gravity feed HVLP conversion gun. The plywood is sanded to 320-grit with a random orbit sander.

I experimented with a couple brands so far, I’ve tried Minwax Polycrylic and Varathane Water-based poly. The Polycrylic was okay-ish but more expensive than the Varathane and not quite as good.

Then I made the huge mistake of buying some Ace Hardware branded water-based poly, when I ran out of Varathane mid-project and didn’t want to drive to Home Depot. Immediately upon spraying, the entire surface of anything that I sprayed was covered in fisheye. I’m not sure if the can I bought was old or contaminated or if the product was just total garbage.

Below are some photos of the problem:

I returned the Ace polyurethane and bought some Old Master’s water-based poly at Rodda Paints, they had two gallons left of the “old” formula (with a date stamp of 2016 on the bottom of the can), on clearance for $20/gal (normally $76/gal). I bought both gallons and tried it out tonight.

My first impressions are that I’d be willing to pay $76/gal for the Old Master’s WB poly in the future. It seems to have lower viscosity and soaks in to the wood more instead of pooling on the surface. It also seems to dry a lot faster. Additionally, it’s the only one of the three brands that doesn’t have the distinct blue milky look in the can. It’s still milky but it’s more of a neutral or warm color, and the overspray on my workbench had to get REALLY thick before it started to look cloudy. It’s either really that good, or they cheated and it has less solids. I’ll find out tomorrow after everything is dry.

I can’t speak for the durability of the cured finish of any of these because my project hasn’t seen any action yet.

-- Woodworking from an engineer's perspective


4 replies so far

View John_H's profile

John_H

176 posts in 1827 days


#1 posted 01-13-2018 06:52 AM

Take a look at General Finishes

Not only do they have a clear poly – they also have pigmented poly in black or white and I think you can even get it custom tinted.

It’s not cheap (around $60 per gallon) but I have had excellent results – especially with the black poly. It dries fairly quickly, pretty easy to sand and can be recoated in less than two hours

here is a link where you can look up vendors in your area
https://generalfinishes.com/where-to-buy

also, take a look at their “High Performance”
https://generalfinishes.com/wood-finishes-retail/water-based-topcoats-and-sanding-sealer/high-performance-water-based-topcoat

Black Poly
https://generalfinishes.com/wood-finishes-professional/water-based-paints-glazes-and-pigmented-top-coats/enduro-pigmented-black

View cracknpop's profile

cracknpop

320 posts in 2470 days


#2 posted 01-13-2018 11:51 AM

Regarding your fish-eye problem…. could it be related to cleaning your gun between finishes leaving some residual soap or mineral spirits in your gun? Did you scuff sand the under coat (Varathane I think??) before applying the Ace brand, wipe it off with rag that could have been contaminated?
I have limited experience with WB poly, know only enough to ask questions.

-- Rick - I know I am not perfect, but I will keep pressing on toward the goal of becoming all I am called to be.

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BB1

1168 posts in 969 days


#3 posted 01-13-2018 11:58 AM

I use a lot of General Finishes – mainly High Performance although also have used their outdoor finish GF 450 (seems pretty good on small fold up table we use when camping). I use a foam brush so no experience with spraying. Have been applying finish in my living room so like the low smell!

View William Shelley's profile

William Shelley

576 posts in 1591 days


#4 posted 01-13-2018 02:39 PM



Regarding your fish-eye problem…. could it be related to cleaning your gun between finishes leaving some residual soap or mineral spirits in your gun? Did you scuff sand the under coat (Varathane I think??) before applying the Ace brand, wipe it off with rag that could have been contaminated?
I have limited experience with WB poly, know only enough to ask questions.

- cracknpop

I cleaned the gun briefly with just warm water, no soap. I like to make a habit of doing this any time I need to refill the gun mid-project to keep the tip from getting clogged and such.

On the thick overspray “pools” on my workbench, I did notice an “oil slick” look on top of the wet finish after spraying the Ace stuff.

Also, the Ace was going down over raw wood, no previous coat of finish on that side of the piece yet.

Anyway, I’m happy so far with the Old Masters, but I love GF Arm-R-Seal wiping varnish so maybe I’ll give their WB poly products a try. Thanks!

-- Woodworking from an engineer's perspective

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