Painting over lime wash

[Leadhillite]

Can anyone give me some advice on how I go about painting on top of lime wash?

Part of my external wall is lime pointed stone, (random stone). It was lime washed a few years back (with about 4 coats of "St Astier" paint), which I'm not too impressed with. I'm wanting to paint over it with a modern breathable paint, as I do not have the patience to do lime wash again. (The rest of the house is concrete rendered and its got modern paint on it.)

Is there anything I should do prep wise? I was thinking that taking a wire brush to it would do the job, as the lime wash just looks like somebodys sprayed coloured water onto the stones and pointing!

Any advice would be greatly appreciated.

 

[oldgreymouse]

Lime wash has its place! It can solve all sorts of problems when used in the right way. The St Austier is good stuff and actually has a good colour range compared to years ago, WHITE!!!

I can understand why maybe you don't like the finish so if you must then to clean it off just requires a good scrubbing brush and water, use an old dust sheet on the floor to catch the bits and watch you don't get it in your eyes so wear gloves and goggles. You could use a pressure washer, although you will have to watch the water run off and bear in mind the limewash dust will then go everwhere.

If only part of the house was limewashed, do you know if it had a problem with damp? Old cottages and other buildings sometimes never had damproof courses so it was quite normal to use limewash as this was never effected by rising damp.
The breathable paints are ok but I did some cellar walls on a town house a few years ago and they did not work very well. Not too sure how good some of the newer paints are as I still stick with limewash in actual damp areas. ( The St Austier paints are made less than half a mile from my home.)

Best not to use a wire brush as you will leave bits of the wire imbedded in the stone, not good for repainting.

 

[Leadhillite]

This is a looooooong story....
Half the back of my cottage has a bathroom extension - brick built and concrete render. My house is built into a hillside, so I excavated down to the foundations, used a specialist waterproof render from foundations up to 1.5' above ground level then backfilled with 40mm gravel back up to ground level. The gable wall was and is rock solid concrete render, but the upper part of the back wall (that doesnt have the bathroom on it), was all repointed in lime mortar. I painted that bit with lime wash, so that if there was any moisture still in the wall, it could escape out that part of the wall.

I guess I am resigned to repainting it again with St Astier lime wash again, cos I hear what you are saying, and as much as I would have liked you to say something else, it does all ring true.

Ive actually still got some of the old paint left. It was bought as a dry mix, and I added water to it. Does the paint have a finite life, or could I still use it? Also, can I add some lime to it to make the paint a bit thicker?

Finally, thanks again for answering my other query about my gable wall!

Very much appreciated!

 

[oldgreymouse]

Hi again and regarding shelf life of the St austier, I guess it just lasts ages, I still have some as a spare just in case a job comes up that needs it. The plastic can has the correct amount of powder to make up one mix with water added 'as it says on the tub'!!
The place that make this stuff is just a 2 minute walk down the road from me and i have always got my lime putty there and then added my own stone dust to make up my lime mortar.
I will call in there on Monday morning and just check what the gen is on getting a thicker cover mix, although I just find 3 or 4 coats, letting it dry in between has covered well enough.

Will get back to you!!

 

[oldgreymouse]

Me again! Following my last post, spoke with the guys at the lime plant.
They tell me that adding less than the correct amount of water, trying to make it a thicker mix will just result in it crazing and cracking. so the suggestion is not to do it.
4 coats of lime wash is normal, allowing 24 hours between coats, I must admit I have followed this rule and it generally works ok. Sometimes darker pieces of stone show through but otherwise it does its job.

I must admit it does not look as white as 2 coats of Sandtex!!!!!!

 

[Leadhillite]

Have to say that our "lime specialist" in the village raved about thickening up the paint, (but only slightly), and now that I think about it, the wall he painted has not even lasted into the next year!

Thanks again.......guess I'll be getting the lime wash out again!