Remove Old Materials From Concrete Before Repainting
LESLIE: Alright, now I’ve got Rich in New Jersey calling in. What can we do for you today?
RICH: Hi, Leslie. I’m working with a bunch of volunteers. We’re trying to fix up New York Military Academy, which is the school where we graduated from. The barracks is the first prefabricated concrete building in the country. It’s solid concrete.
TOM: Oh, how interesting. Prefabricated. And what year was it built?
RICH: And we’re all volunteer labor.
RICH: But there’s a question going back and forth and we’re trying to get an issue settled.
TOM: (chuckling) OK.
RICH: Half the guys are saying that we’re crazy if we don’t scrape this hundred-year-old building down to the original concrete before we repaint it. And the other half says we’ll do just as well to patch and fill and then apply the spray paint and just come back in three to five years. And we’re just going back and forth and we can’t seem to get any resolution, so I thought I’d call the experts and ask your opinion.
TOM: Well, I’m sure you’ve got lots and lots of layers of probably some of that good, old-fashioned lead paint on there, which means you’ve got to be a little bit careful with this process. But the general rule of thumb is you want to get as much of that off as humanly possible. Now it may not mean going all the way down to the original masonry surface, concrete surface, but you certainly have to get down to where you’re looking at something that’s very solid.
The next thing – and this is going to be a very critical part of this – you want to make sure that you prime this. Because you have to understand that primer and exterior paint have separate qualities. The primer is the glue that makes the project, makes the paint stick. And so if it’s not primed properly, it’s not going to stick.
Now if you have damage to the wall, then you need to use a patching material made of epoxy; an epoxy patching compound. There’s a company called Abatron – A-b-a-t-r-o-n.
LESLIE: They make a great selection of all sorts of patching materials that’ll really cause good adhesion.
TOM: Yeah, and that’s the key.
RICH: Good, old-fashioned spackle is not the solution.
TOM: (overlapping voices) Not going to – no, absolutely not.
LESLIE: (overlapping voices) No, it’s not going to stay.
TOM: And any type of concrete that you put on there, not going to work. It’ll fall right off the very first New York winter you get at the New York Military Academy. OK?
RICH: Thank you.
TOM: Critical you use an epoxy patching compound. It’s got the qualities to make it stick. Critical you paint it – prime it first – then topcoat paint it. And I think if you do that properly – the nice thing about masonry surfaces is, unlike organic materials like wood siding, that paint can actually last 10 or 15 years because think about it: you don’t have the expansion and the contraction that you would have associated with a wood surface, so it does tend to last a long time. Definitely worth, though, taking the time on the prep.
Now even though it’s very painful – you’re going to need a lot of hands for this – definitely worth getting it straightened out right now because this way you’ll be able to do it once, do it right. And then by the time it’s ready to paint again, your kids can do it. (Leslie chuckles)
RICH: That’s good to hear. That’s good to hear. Is the preferred technique a sandblaster?
TOM: You have to be very careful with a sandblaster because you can damage the original concrete surface, but it’s not a bad thing to try because you may find that it comes off easily that way.
RICH: Well, thank you. That’s a good piece of advice. And now that we’ve heard from the experts, I can win the bet at the bar. (Leslie chuckles)
TOM: Well, we’re happy to settle the bet. Rich, thanks so much for calling us at 888-MONEY-PIT.
And what a great project for a bunch of guys to do. You know, if you are working on projects like that around the country – we always ask you to call with your home improvement questions about your house but …
LESLIE: And send pictures.
TOM: … certainly if you’re doing a project for charity like that – if you’re working on a community event; perhaps building a playground or fixing up a building for a deserving group – we’d love to hear about that, so pick up the phone and call us at 1-888-MONEY-PIT.