Proper pre-paint preparation for brick
Howdy all–
So I erected scaffolding last October on the back of the house for replacing the gutters, which lead to reroofing the back of the house, which lead to repairing a ton of masonry, which lead to replacing all the window sills, which lead to replacing all the window frames which lead to… you get the idea.
Anyhow, I was about to tear down all the scaffolding and return it when I looked at the terrible paint on the back of house and I got that sinking feeling that the smart thing to do would be to repaint while I have the scaffolding up…
The brick is from 1892, so is very soft, and it’s got at least three layers of paint on it. In some places it’s flaking and peeling really badly, exposing raw brick underneath, in other places it’s fine.
I have been considering two routes for surface preparation:
1) strip it bare using PeelAway. I’ve spot tested PA, and it works fine, though it does take time, and some elbow grease.
2) wash and just scrape the bad spots.
I’m concerned that due to the hodgepodge of paints on the brick, and the spotty present condition that just scraping/washing it isn’t going to give the paint a good base to work off of… Are my concerns unfounded? Stripping it bare is going to be a lot of work, and at that point I might as well go nuts and try whitewashing it, as I’m super intrigued by the whole process and its history. If my better judgment prevails, an acrylic masonry primer and paint will be used, though I am worried about the permeability of the old paints + new primer + new paint. I don’t need to put any more stress on the old brick than it already has…
Z
Replies
Greetings mack,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
Let's run this thru one more time.
Bump
ok first...
the type brick you have should never be painted, you have a very soft wood fired brick and it was placed with a lime mortar... you'll notice you have no expansion joints... because as laid your bricks were about 800psi and the mortar was 250psi... and lime mortar is self healing... yep it's supposed to move and breath and it will seal itself up when small cracks form... you have an air space between layers of brick that will weep or catch or absorb any moisture that gets past the 1st layer...
by sealing it all up... (painting it) you are trapping moisture in the brick and inner layers... and it will always peel, flake, sprawl, and bleed...
but since it is already painted and ur only real choice (vs stripping it all) is to repaint... clean it well... pressure wash it... and paint it with a latex paint while the brick is wet... guess'n you can run a hose full blast at the top onto the brick and none would make to the ground it absorbs so much ... you don't want it suck'n the moisture out of the paint before it can dry.... there are "portland paints" that might work... (portland & water)
good luck
p
The 19th century soft brick, while it may never have intended to be painted, does not do well over time in our present acidic weather environment.
Strip with PeelAway (which one???) Some require neutralization (1 I think) and some don't (6 and 7). Once you are to bare brick, use an alkaline masonry primer - I highly, highly recommend Sherwin Williams Loxon Primer. Then 2 topcoats with latex.
Jeff