LumberJocks

How to fix blotchy deck stain?

  • Advertise with us

« back to Finishing forum

Forum topic by crampon posted 05-17-2021 12:01 AM 289 views 0 times favorited 6 replies Add to Favorites Watch
View crampon's profile

crampon

20 posts in 3362 days


05-17-2021 12:01 AM

Hi all, I posted this question as a continuation of an old thread in the woodworking forum too, but thought I might get more eyes here. I just had an old tongue and groove fir porch floor replaced with new CVG fir tongue and groove. Sherwin Williams recommended their combo stain+sealer Super Deck product; I’m using the transparent formulation in natural so the fir color can come through.

It was my first time using this product; it went on surprisingly thinly, I used maybe a 1-2 cups for 125 square feet. I thought it would self-level and soak in, but neither of those was true and now I have blotches (pics below). It went on yesterday – I’m trying to take off the blotches with mineral spirits and rags, but it’s slow going and I’m not getting perfect results – trading dark blotches for pale blotches.

Is there a better way to approach this? Is sanding down and refinishing the only other option?

Pics of the crime scene below. Viewers who are sensitive to graphic images, please don’t read any further.


6 replies so far

View Madmark2's profile

Madmark2

2841 posts in 1707 days


#1 posted 05-17-2021 07:15 AM

Its blotchy because of uneven application and/or improper mixing.

You can see that the “splotch” follows the visible brush stroke and not the wood grain. Ergo its an application fault and not a materials issue.


The splotches cross boards so its not the decking!

Go back and reread the instructions. You said yourself that the mix rate seemed off. Coverage is typically maxed at 300 sq ft per gallon. Some thicker materials may only give 100-120 sq ft of coverage per gal. But 1-2 CUPS! That’s only a pint, 1/8th gal or at most 300/8, enough to cover 37-1/2 sq ft. If you covered 125 sq ft with that amount, your mix rate was 1:4 or even 1:8, really thin.

Mix your materials better and put a complete, even, coat on and see if things don’t even out.

-- The hump with the stump and the pump!

View LesB's profile

LesB

3011 posts in 4562 days


#2 posted 05-17-2021 04:59 PM

+1 for MadMarks comments.

Obviously the sealar was not “clear” but had a slight amber color. A second application may blend in the spots but it will not dissolve and even them out like shellac does. However if that doesn’t work you have two coats you will need to remove before starting over. It would be safer to sand to remove them first and then do a better job of putting on another coat.

In hind sight, Fir is quite absorbent so in this case it might have been better to put on a coat of clear dewaxed shellac with a light sanding to remove any raised wood grain (if there is any) and then put on your choice of top coats for better wear and sealing factors.

-- Les B, Oregon

View crampon's profile

crampon

20 posts in 3362 days


#3 posted 05-17-2021 06:05 PM

Thanks gentlemen, no argument that the dimwitted jerk who slopped on the product (i.e., me) was at fault. Not a mix issue though, the product was premixed, so I didn’t dilute it, and I kept it well-stirred during application. I’m going to live with it for the summer and then when things cool off a bit getting into fall, I’ll sand it off and try Les’ suggestion of a clear shellac bottom coat followed by light sanding for raised grain before this goes on.

View Madmark2's profile

Madmark2

2841 posts in 1707 days


#4 posted 05-17-2021 06:36 PM

Premixed?

Who “premixed” it?

What did they mix? & what with? & in what ratio?

Just because it was “premixed” doesn’t mean it was premixed correctly!

Buy a gallon of “spar urethane” and an empty gallon can. Pour 1/2 the stirred urethane (not “poly”) in the can and mix with mineral spirits. Use the 50%-50% mix for two coats and the remainder of the original can full strength for the final coat.

This will cover the splotches caused by too-thin mix, penetrate, seal, and give a durable finish from the final full strength coat.

-- The hump with the stump and the pump!

View crampon's profile

crampon

20 posts in 3362 days


#5 posted 05-17-2021 06:52 PM

Sherwin Williams sells it in gallon cans so…premixed at their factory, I suppose. The cans have factory labels, so it’s not one of those products where tint is added at the store or anything. This is the specific product.

View Madmark2's profile

Madmark2

2841 posts in 1707 days


#6 posted 05-18-2021 01:30 AM

Its not finish. It’s stain. Thats why it went on thin. Get real urethane varnish, not stain.

-- The hump with the stump and the pump!

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com