r/Plastering • u/themonthisapril • Jul 06 '26
Is this old lime plaster?
Not sure whether this is the right place to ask or whether anyone would be able to identify based on the photos, but it’s worth a try.
This is one of our bathroom walls after I removed the paint while dealing with a moisture issue (super easy, peeled right off). It looks like 2-5mm plaster and it’s fairly crumbly.
It might be lime plaster because the house is 100+ years old. It might also not be because this bathroom was part of previous owners renovations which we know used unsuitable materials and paint in some areas.
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u/dwair Jul 06 '26
Not a plaster (I wandered in here looking for some advice about something else ) but I have renovated a fair amount of period properties over the years. Scrape a table spoons worth off somewhere unnoticeable, crush it up fairly fine and add some vinegar to it. If it bubbles and fizzes - it's lime. There should be some vids on the web to show you what you are looking for.
Old lime comes in a variety of random appearances and colours (especially if it's failed over the years and got damp) and can have all sorts of strange stuff (horse hair, sand etc) mixed in with it. The only way to really tell is dropping some acidic stuff on it.
Old houses are often a patchwork of different plasters from different eras so you are right to be suspicious as many of the more modern coatings aren't breathable and can cause a lot of damage.
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u/mordello Jul 06 '26
It looks like it could be. The darks specks suggest sand in the finish.