What Lime plater to use on painted masonry?

[Mulder]

Sorry, I've got another "which lime do I need" question, but I haven't been able to find the answer in the search.

I have brick internal walls. They are painted in a few layers of thick lead-based paint. It adheres very well to the brick and requires a lot of chipping and physical effort to remove, which I really don't want to do due to lead and risks around small children.

I want to plaster the walls, ideally with lime. I have some NHL lime mix (SecilTek Lime) that has some adhesive in (I know, not ideal, but I've got a few bags that need using up). I'm confident this will adhere to the paint.

But I'd rather use Lime Putty due to its longer set times and nicer finish.

Can lime Putty plaster be applied over a base coat of NHL? Or is there something else I can try? I'm not too concerned about breathability on these particular walls as they are internal.

 

[Kearn]

Breathability is probably close to nil with a good coating of the lead over anyway! And as you say internal, so less vital. That doesn’t mean the lower sections won’t be prone to potentially wicking up moisture if the bricks are in direct contact with the ground.

There’s no reason putty can’t go over NHL, just give it the appropriate scratch / key before it goes off to match with the aggregate size and planned thickness of top coat.

 

[Mulder]

Breathability is probably close to nil with a good coating of the lead over anyway! And as you say internal, so less vital. That doesn’t mean the lower sections won’t be prone to potentially wicking up moisture if the bricks are in direct contact with the ground.

There’s no reason putty can’t go over NHL, just give it the appropriate scratch / key before it goes off to match with the aggregate size and planned thickness of top coat.

Thanks Kearn.
I assume applying lime putty plaster direct to the paint (and avoiding the NHL scratch coat) wouldn't be a good idea as the surface won't be porous enough to provide sufficient adhesion?

 

[Kearn]

Not sure how much adhesion you’ll get with nhl either without a decent scratching of the paint below.

 

[Lacan07]

Sorry, I've got another "which lime do I need" question, but I haven't been able to find the answer in the search.

I have brick internal walls. They are painted in a few layers of thick lead-based paint. It adheres very well to the brick and requires a lot of chipping and physical effort to remove, which I really don't want to do due to lead and risks around small children.

I want to plaster the walls, ideally with lime. I have some NHL lime mix (SecilTek Lime) that has some adhesive in (I know, not ideal, but I've got a few bags that need using up). I'm confident this will adhere to the paint.

But I'd rather use Lime Putty due to its longer set times and nicer finish.

Can lime Putty plaster be applied over a base coat of NHL? Or is there something else I can try? I'm not too concerned about breathability on these particular walls as they are internal.

I think traditionally in this situation you'd grab a chisel and hammer and knock a notch out of each brick to create a key. To be safe I'd chisel 2 notches per brick. Time consuming but not as bad as removing the paint all together.

I know nothing about SecilTek but you can easily apply non hydraulic lime over NHL, just make sure you key the NHL base coat with a scarifier.

They say lead paint is breathable but to what extent I couldn't say.