[bluegrassdan]

Working in a school with many hallways with cinder block walls that have been painted with latex over oil.
Would not be feasible to remove the latex. Not allowed to use oil products so put a coat of Bondz on. The trim is oil and the Bondz sticks to it but the walls dont pass the scratch test after a week of drying. I dont think the problem is fixable and have told them as much but any crazy ideas out there?

 

[bluegrassdan]

Maybe Peel Stop or something similar?

 

[Joe67]

It's pretty much FUBAR. That latex layer isn't bonded, and nothing you put OVER it will bond it. I might have suggested to at least try some Gardz, as it might have done some penetration of the latex layer/s and helped. But now with the Bondz on I'd imagine the odds are near zero. You could always try a test spot though.

Seems a weird time to be doing a school. I'd suggest waiting for a summer period when school is out, a bunch of power sanding & scraping, and then a bonding primer? Or you just paint it, and whatever stays on stays on!

 

[bluegrassdan]

It's pretty much FUBAR. That latex layer isn't bonded, and nothing you put OVER it will bond it. I might have suggested to at least try some Gardz, as it might have done some penetration of the latex layer/s and helped. But now with the Bondz on I'd imagine the odds are near zero. You could always try a test spot though.

Seems a weird time to be doing a school. I'd suggest waiting for a summer period when school is out, a bunch of power sanding & scraping, and then a bonding primer? Or you just paint it, and whatever stays on stays on!

most of it hasn't been primed yet. Maybe I will try that.

 

[Joe67]

most of it hasn't been primed yet. Maybe I will try that.

I don't know whether you've used it or not, but its very stinky while it dries. (I actually use a respirator if I'm doing more than a little bit of something). Doesn't linger though, so it's not like oil in that regard. Just mentioning it b/c you're in a school and probably don't want others around during application.

I am skeptical that it will work - but vary curious to know what you find.

 

[Holland]

Working in a school with many hallways with cinder block walls that have been painted with latex over oil.
Would not be feasible to remove the latex. Not allowed to use oil products so put a coat of Bondz on. The trim is oil and the Bondz sticks to it but the walls dont pass the scratch test after a week of drying. I dont think the problem is fixable and have told them as much but any crazy ideas out there?

You might be okay with your Bondz coat...

I am not familiar with Bondz per se, but it is a "Urethane Modified Acrylic Bonding primer". It seems to be unique to "low-VOC, high solids water-based primers", that full adhesion is not achieved until full cure (usually 21-30 days).

Best advice is to wait until the end of that time to make final judgements regarding adhesion.

 

[Wildbill7145]

Wow. An entire school of cinder block walls with latex over oil. I can't imagine a worse scenario. I'm with Joe67. They're hooped. The only fix to this would be to remove all the latex and use a bonding primer over the oil which is never going to happen. Putting anything on top of the latex is basically a band aid and a waste of time. Even if Gardz could get to the oil which would be a miracle, it's certainly not rated as a bonding primer to be used over oil for conversion purposes.

 

[comtnpaint]

You might be okay with your Bondz coat...

I am not familiar with Bondz per se, but it is a "Urethane Modified Acrylic Bonding primer". It seems to be unique to "low-VOC, high solids water-based primers", that full adhesion is not achieved until full cure (usually 21-30 days).

Best advice is to wait until the end of that time to make final judgements regarding adhesion.

All I know about it is it was Rustoleum's knock-off of UMA from before Rustoleum bought XIM.

 

[Joe67]

Gardz is designed for new drywall, but works (to a degree) over flat paint when it comes to penetration through the flat paint and "glueing" it

Lots of things are designed for new drywall. If that's all you know about Gardz, then this is another case where you don't know as much as you think that you do. Seems to be a theme.

It probably won't work, as I noted. But Gardz does penetrate porous surfaces and bind them. Latex paints are porous regardless of gloss, though flats tend to be more porous. No one said "just use Gardz." The idea is that it is an impossible situation. But a test spot with Gardz is at least worth a shot. It will cost a tiny amount of time and material to find out.

 

[bluegrassdan]

thanks folks

 

[thepm4]

Can u have them sign a waiver?

 

[Rbriggs82]

When did you use Bondz?

 

[finishesbykevyn]

Because the cinder block is not smooth, it's hard to get a sander on all of it. However, in those situations I have suggested if not doing a complete removal, to sand the crap out of it with 80-100 grit pole sander. Whatever comes off, comes off. Then apply your bonding primer and top coats. It'll last.. for a while..

 

[Gwarel]

Because the cinder block is not smooth, it's hard to get a sander on all of it. However, in those situations I have suggested if not doing a complete removal, to sand the crap out of it with 80-100 grit pole sander. Whatever comes off, comes off. Then apply your bonding primer and top coats. It'll last.. for a while..

This makes sense to me. I don't think it would be necessary to remove all of the latex top coat, just sanding off what will come loose should give you enough of a surface area for the bond coat to adhere to and create a skin for the new coating. I just did something similar to some doors and frames.

 

[finishesbykevyn]

just as an example of "surface tension",
as great as the SHW Duration exterior paint is, there were incidents that when that paint was applied over old layers of paint it "pulled" the previous layer-layers of paint off
SHW Duration is an excellent and a very durable paint on new surface, but it might cause problems on previously coated multi layer paint surfaces
but this goes for BM exterior paints as well, (and for other brands also), they too might create surface tension paint separation, and there is no definite formula when it might happen
best wisdom is not to use too high grade (to high quality) paint regardless of the brand, over multilayers of old paint
better is to use lower grade (with less super duper chemicals in it) exterior paints to avoid "surface tension" mess

i know this sounds crazy, but this is the reality of compatibility of different paints, of very different chemical materials
most of the times there are no problems, but when there are problems, this is most likely the reason
excluding very insufficient prep work of course

I think you're misunderstanding what surface tension is. The idea of a bonding bridge/tie coat is to eliminate any "re-activating" of previous coatings. Surface tension is generally caused by an incompatibility between 2 products and/or surface contamination. Obviously complete removal is the only surefire way to be 100% certain, but not always feasible.

https://en.wikipedia.org/wiki/Surface_tension

 

[Pullman Painter]

Working in a school with many hallways with cinder block walls that have been painted with latex over oil.
Would not be feasible to remove the latex. Not allowed to use oil products so put a coat of Bondz on. The trim is oil and the Bondz sticks to it but the walls dont pass the scratch test after a week of drying. I dont think the problem is fixable and have told them as much but any crazy ideas out there?

Where is the failure during the scratch test? Is the old latex peeling from the old oil? Is the old oil and latex pulling from the brick? If the bond between the latex and old oil is good aka they previously used a proper bonging agent, i think you just need a better paint or bonding primer lol there is bo reason latex would not set up well over latex. Is it possible the cure time of the product you were using is Over a week?

 

[mike mineral spirits]

Working in a school with many hallways with cinder block walls that have been painted with latex over oil. Would not be feasible to remove the latex. Not allowed to use oil products so put a coat of Bondz on. The trim is oil and the Bondz sticks to it but the walls dont pass the scratch test after a week of drying. I dont think the problem is fixable and have told them as much but any crazy ideas out there?

Two schools of thought. 1. XIM UMA waterborne urethane will expose any weak or peeling areas on the cinder block. Must wait 3 days for a full cure on the primer. Address the peeling areas with a second coat then after two days apply the top coat. 2. The Bondz or Gardz has less adhesion strength and acts as a Tie coat between the finishes. Will not accelerate the peeling. Face the facts. The coat of latex is something that may be able to be fixed. Bring it to the supervisor attention that due to the precarious substrate another coat of paint will hide the problem. Think of it as a floor in a commercial area. If the coating is soft and peeling nothing can be put on a bad coat of paint to fix it. It probably could be removed with sandblasting. Good luck