ᐅ Making and storing lime plasters yourself

Hello,

I intended to make my own mortar but I am not sure if it hardens by itself while packed. Can someone explain how to prepare lime plaster so that it can be bagged and stored until use?

The mixture is simple:

Lime and sand

Sorry, but the answer is "not at all." Unless you have the appropriate bags and equipment to work airtight.

When doing it yourself, the focus is on producing, not storing. So produce and then use immediately.

So, does that mean I have to airtight-seal the lime-sand mixture? What types of bags could be used? Which machines? I was thinking just to put the lime-sand mixture into the concrete mixer and then into the bag. How do companies handle their lime plasters, like Knauf and others?

Just ask the companies where they source their bags from and which production machines you need to order.

I can only tell you that calcium hydroxide (hydrated lime) reacts with humidity in the air. Initially, clumps form, and eventually, the bag becomes rock hard. This also happens with factory bags, but it takes much longer (years). It’s chemistry and cannot be avoided without airtight packaging.

I can already see that storing the materials won’t be as easy as I initially thought. I believe airtight packaging will be the least of my problems (plastic bags sealed tightly). The sand I mix in must be completely dry as well. It would even be sufficient for me if I could prepare a stockpile for about a week, so roughly a one-week shelf life.

Pure lime plaster is simply too expensive, and no one would pay that much per square meter. However, it looks much too good when applied as a base coat. Does anyone have any suggestions on how this might be possible?

Pure lime does not harden, not even from humidity in the air. Basically, you can mix it with sand and store it in plastic bags. Naturally, it must be kept dry, of course.

As soon as cement is added, it hardens after a certain time.

For example, adhesive and reinforcement mortar also do not harden. Masonry and screed concrete harden relatively quickly. Lime-cement plaster hardens more slowly.

The bags from hardware stores contain a plastic layer in the middle between the paper, which makes them relatively durable.

I once had a bag of lime stored in a barn with quite high humidity. Even after 10 years, it was still perfectly fine despite the package being opened. That surprised me myself.