
How to restore an old stone wall
by
Jan
on Thu 01 Nov 2007 10:20 PM CET
Our house is from 1762. When we bought it, it had been empty for a few years and it had been raining through the roof. It was basically in a good condition but needed quite a lot of renovation. As the house is the oldest existing house in the village, except for the castle, we though it was worth being renovated in a cautious way. All the floors was the original ones and one of the walls was even older than the house and had belonged to the old fortress that had been there as far back as the 11th century and maybe longer.
One of the first problems we encountered was how to renovate the walls. They were now covered with disgusting wallpaper in many layers. When we took them away – which was quite a job – we found the original painted walls. The original walls had just patterns like dots, flowers and other decorations painted on the plaster covered walls. We would have liked to restore this but it was impossible as they had been too damaged by the time and what was left of it disappeared when the wallpaper was taken off.
Anyway we decided we wanted the walls painted in traditional earth colours, the way they used to do it in the south of France, in such a way that the texture of the walls would appear through the paint.
This was however not easy to do as no shop that sold paint could inform us how to do it. The thing was that we wanted to find a transparent paint, a so called glaze, for our old walls. That was not a problem – the problem was to know how to prepare the old walls for application of this glaze. Every shop wanted to sell us some artificial product to make the walls look old before we applied the glaze. We tried to tell them that our walls already were 250 years old and we wanted to know just how to prepare them for glazing. They could not tell us how to do this but persisted that we needed this artificial coating on the walls to get the glaze to stick and get the “right” old fashioned look. So – we had to try different ways ourselves. Finally we found out that we could apply this glaze, which really is a wax (it is called “cire” in French), that you can apply to any pre-painted wall. So, this is the way we did it:
Naturally the walls had quite a few damages like cracks, holes from nails and other fitting and also some damp pieces. We also had to knock down large pieces where the old plaster was loose from the supporting stones. The walls were built of large stones and covered with plaster so they were fairly even – but the charm is that they curved quite a lot and were wider at the bottom than at the top. We mended all the holes with plaster. We scraped down the cracks quite deep so the new plaster would get a good grip and filled them with plaster. You should use the kind of plaster that do not sink when it dries so you can make the surface finished in one go. Do not overfill and think you should sand it down afterwards. That is hard work! Instead fill up the cracks and holes with a mixture that is dry enough not to run and liquid enough to get down in the holes, let it dry for a few minutes until it is like hard parmesan cheese, cut away the surplus with a sharp scraper and coat it with slurry of plaster with the help of a very even steel spatula or even better, with a square spatula with a rubber surface. In this way you get a finished surface in one go. It is important that you soak the part of the wall with water before you apply the plaster. It will dry immediately otherwise and you will not be able to get a good surface. The plaster dries very quickly so make small portions or, as the experts do, mix it with water as you use it.
When you have finished this mending of holes you need to give the wall a final coating with something the French calls an “endui”. This is also based on plaster, but with much finer grain which, unlike the first plaster, keeps open for many hours. You have to cover the whole wall with this “endui” otherwise the paint will soak into the wall unevenly and you will get very ugly spots when you put on the “cire” in the end.
Now is the time to do something about the parts that you know are damp. Stone walls have a tendency to suck up water from the ground so often the walls are damp or even wet at the bottom. You can buy a special product to seal the wall with. You just apply one coat with a brush and let it dry according to the description.
When you have coated the wall with “endui” and this seal you should give it two coats of acrylic paint. I used white as I wanted the colour to come from the “cire”, but you can take any light colour and put a “cire” on top. If you do not use white I suggest you test first.
Here is the time for some warning!
It is tempting to make your wall very even but do not do that, because you want to keep the old look. They put this artificial coating unevenly on modern plasterboard walls to make them look old so you should not overdo your plasterwork and your coating with “endui” to make your old wall look new. The trick is not to make the first plaster too even and to apply the “endui” in different directions and finally not to paint with the acrylic paint as you are used to. Do not use even stokes as you are taught to do; try to paint as you five years old child would have done. The way you do this determines how “lively” your wall will be in the end.
When your paint is dry you start with the fun work – to apply the ”cire”. The “cire” is a coloured wax with the same consistency as soft shoe polish from a tube. You apply it on the wall with a brush and rub it in and away with a sponge. Here you can decide how much colour you want to leave on the wall to get a deeper or more subtle look.
The final result is exactly what you can see in old houses from Provence. When the “cire” is dry the wall is washable and has got a silky shiny look. Beautiful!!
Just a few more thing!
If you have very deep dents or holes in the walls or have wooden beams or other moving constructions, you should mix the plaster fifty-fifty with something called MAP. This makes the joint a tiny bit elastic so it can take some movements. You can also use MAP as it is for very big holes and where the movements might be large.
If you have parts that are painted with old linseed oil paint you can not apply modern paint on top of it. It will not stick or it will crackle. In this case you have to isolate the old paint with a coat of a paint based on “glycérophtalique” (I think it is an alkyd paint). You can use this method to isolate any old coatings or stains from sot in chimneys or any other agents that might come through the finished paint.