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peterg820

05:43AM | 11/12/08
Member Since: 11/11/08
2 lifetime posts
Bvbrush
I recently used a Minwax Oil-based Polyurethane to seal my exposed brick. The problem I encountered is that on some of the bricks they turned an opaque color. I'm trying to figure out why! It's only happening to certain bricks. I started trying to problem solve and I've eliminated the following possibilities: 1. I removed all dust evenly. 2. I acid washed the wall with a mild acid, and rinsed thoroughly, and where the acid was most concentrated, the polyurethane didn't discolor.

Here's my hunch: 1. Some of the brick absorbed more moisture and weren't completely dry (I did let it dry for 48hrs.) so the polyurethane reacted with the moisture? 2. The bricks that turned opaque didn't have enough polyurethane on them...(the following morning I applied a second coat to a small area of the opaque brick, and it turned it clear again...but I haven't seen it dry yet (went to work)....

IF ANYONE CAN GIVE ME SOME GUIDANCE, I WOULD REALLY APPRECIATE IT!

5slb6

01:51AM | 11/13/08
Member Since: 07/28/02
1356 lifetime posts
It could be moisture still in the brick as 48 hours may not have been long enough. You may just have to give a few lore days and see if it clears up on it's own.

If you are using a satin finish it could be the flattening agents staying on the surface of the more pourous bricks. You see polyurethans start out as gloss and flattening agents are added to dull it down. It cases like this you need to seal with a gloss and follow with satin.

peterg820

02:55AM | 11/13/08
Member Since: 11/11/08
2 lifetime posts
Thanks for the input. It seems that re-coating the brick is the solution. I think it's a combination of the dulling agent and needing more urethane on the brick itself. Thanks for the help.

Faron79

07:24PM | 11/13/08
Member Since: 08/20/04
32 lifetime posts
Not trying to be harsh here...just curious.

Why did you apply Polyurethane to bricks?!

Where was this used...inside or outside? Wall or other item?

Polyurethanes will "cloud", and/or start peeling if moisture is coming through. This makes poly's very poor choices for brick surfaces. They just can't breathe very well.

UGL makes good brick/concrete sealers that do a good job of sealing & holding-up to effloressence & salt deposits.

http://www.ugl.com/drylokMasonry/clearProtectors/concreteProtector.php

In all honesty, I'd try to strip off that oil poly! It'll be nothing but a maintenance headache...

Faron

5slb6

03:59PM | 11/16/08
Member Since: 07/28/02
1356 lifetime posts
There is nothing wrong with oil based polyurethane on interior brick as I have seen it used many times. I also doubt you will have efforessence on an interior brick unless you have some major moisture problems and that would have shown up long ago.

Also alot of these masonry sealers do not have a gloss to them and I am think that is what they are looking for.

Faron79

05:45PM | 11/16/08
Member Since: 08/20/04
32 lifetime posts
The OP was describing classic moisture issues.

Yes, this may be from cleaning the brick, and moisture coming out.

BUT...now the water is trapped, with no way out.

Sorry, but I've never heard of doing this with Poly...especially OIL poly.

We still haven't heard whether this was on an Inside or Outside surface.

Above-grade or below-grade either...?!?!

Faron

BV000631

11:14AM | 03/18/13
my brick is below grade indoors and mineral crystals are forming...i clean the crystals and they come back. definately know that moisture is a factor... how do i seal these bricks from further moisture and crystals?

BV004665

03:31PM | 06/13/14
I have a problem with the AC drip water dissolving the mortar
Can I use this?
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