Limewash (2005) [pdf]

lime.org

23 points·andsoitis··6 comments

I actually have a lot of firsthand experience with limewash on stucco. I don’t know if our lime guy is just screwing it up, but I have been very unimpressed. The claims of vibrancy and longevity just don’t pan out in my experience. A house project I worked on last year used limewash and it’s already falling off and fading. It may have been the contractors not applying it properly, but our lime guy himself said the issue was applying to a wall that the sun was hitting, so it dried too fast. It seems like a very fragile process to get everything right, which makes it a huge pain to use.

One of the first things that this PDF talks about is the application of limewash to different substrates, and how different substrates must be prepared differently.

It sounds like the kind of thing a lot of tradespeople would screw up- like it requires study to do properly. They specifically call out how mortars and renders (which includes stucco) should be composed with the 'mechanical keying' of limewash in mind.

Most important preparation in my experience is to mist the substrate before application to prevent rapid drying.

The last paragraph on page 10 has some interesting information on applying in very dry and hot conditions. Repeated wet/dry cycles each day during application are important for promoting the carbonation to make the final surface durable.

It has to dry slowly to crystalise properly. Hanging damp hessian over the freshly painted wall is a common practice.

It's the same when using lime mortors, you are generally looking for a three day cure for mortor. Lime does not like the sun, wind, or rain (basically any weather!) during this time.

Some good information on lime can be found here:

https://www.scotlime.org/

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