1930s House

[MalcO80]

Hi all, good to be in the forum.
I have recently just bought a 1930 Semi in Aldershot. I have just taken off all the painted wall paper in the rooms and started the process of preparing for painting the walls. However, my Dad recently visited and mentioned that the walls looked like lime plaster and that i should be careful with what paint i use on the walls? At this point I stopped all work as at this point, as I had already used a primer/undercoat on the hall, stairs and landing, as well as the living/dining room walls.
Anyway, I searched ways to test the walls (although not 100% aqurate) with white vinegar (fizz test) and on the area I tested i didn't notice any fizzing.
Whatever the plaster mix is, it is applied directly to brick throughout the house, including the internal/dividing walls.

My question now is, how can I be certain I'm not sealing more walls when it could be lime plaster?

the first few photos are from part of the living room walls and the one with the mustard colour wall is of my daughters room.

any help and advice be very grateful.

Malc

 

[Cubist]

May I ask.... did you take a small divot or chunk of the old plaster and immerse it in the vinegar or did you just paint the vinegar on? I ask because the primer/undercoat may cause failure of the fizz test - you will get the best/more reliable results from this by fully immersing the sample.

Your Dads probably right but cement based plasters were introduced to the UK in the early 18th century so its not absolutely sure without an effective test. However, if I were you I would err on the side of caution and assume he's right. Too late to worry about the primer/undercoat now but there no reason not to go for a breathable paint for the final finishes.

 

[MalcO80]

May I ask.... did you take a small divot or chunk of the old plaster and immerse it in the vinegar or did you just paint the vinegar on? I ask because the primer/undercoat may cause failure of the fizz test - you will get the best/more reliable results from this by fully immersing the sample.

Your Dads probably right but cement based plasters were introduced to the UK in the early 18th century so its not absolutely sure without an effective test. However, if I were you I would err on the side of caution and assume he's right. Too late to worry about the primer/undercoat now but there no reason not to go for a breathable paint for the final finishes.

Hi,
Thanks for the reply. I took a small chuck off an unpainted/primered wall and submerged it, but it was a quick test. If it is a cement based plaster will that be OK to use 'normal' emulsion paint or should I still go for a water/mineral based paint as I should for a lime based plaster? I think I'll do a more extensive test in white vinegar?

 

[Cubist]

The fizz test is far from being an absolute but it is best to keep an eye on it for a minute or two for any reaction. Bluntly, unless the cost of the paint is a major consideration, I would go for a breathable final finish unconditionally.

 

[MalcO80]

The fizz test is far from being an absolute but it is best to keep an eye on it for a minute or two for any reaction. Bluntly, unless the cost of the paint is a major consideration, I would go for a breathable final finish unconditionally.

Perfect! Thank you very much for your advice.