I am attempting to repair a room with heavily damaged plastered walls and ceiling, without ripping out all the old stuff and starting from scratch, or as some local contractors recommend, replacing it with drywall. The house was built circa 1865, with wood lath and two coats of lime plaster, with the under coat reinforced with animal hair. Besides numerous cracks, there are a few large voids where the old plaster has fallen completely off, that will need to be completely re-plastered.

1. Can anyone recommend a suitable bonding agent that would make new plaster adhere satisfactorily to the old wood lath? According to numerous sources I have read, plaster adheres well to freshly cut wood, but poorly to old wooden lath where the original has come loose, and that a bonding agent should be used. I see ads for a product called Larsen Plaster Weld but I get the impression that this is designed more for adhering new plaster to old plaster or to masonry, rather than new plaster to old bare wood.

2. Is there any readily available source of genuine lime plaster? I see numerous articles advising against using materials like setting compound intended for drywall, but no-one mentions where to find a lime mix, or a recipe for making one's own lime plaster. I believe that amongst other things, lime plaster would be less prone to future damage from water leaks, than would be gypsum-based drywall mud, and besides, in a restoration it is always better to replace old material with something as close to the original as possible. If such a thing is made, I would prefer a dry mix to which I would just add water, rather than a concoction of materials likely to be time and temperature critical. Local suppliers can't tell me about anything other than drywall mud and setting compound.

3. Plaster Magic has been highly recommended for less serious cracks, but it is almost prohibitively expensive for the amount of cracks I would need to repair. Some have suggested that regular construction adhesive using the same techniques, works just as well. I would welcome any advice on this, and any other useful advice on how to restore rather than replace damaged old plaster. I ripped out crumbling plaster in another room and replaced it with drywall, but I was less than happy with the end result.

Don