Mistakes made in clay plastering

In the colder weather, my clay plaster walls have taken a little longer to dry out, however in the last week, they have started to look significantly drier and the mistakes made in mixing the plaster is now starting to show!
The pictures below are a good example of how varied my clay plaster was. Being the impatient & busy person I am, I abandoned the idea of waiting for a weekend to do a big plastering session with a good mix, and just mixed a batch of clay plaster up in a bucket an hour a day and worked my way around the walls of the building.

This got the job done in the week, which was handy, but as you can see, I had some good mixes and bad mixes. In the middle of the job, I ran out of sand, and ended up switching from sharp sand to builders sand. It turns out I needed more builders sand in a mix than I needed sharp sand. This resulted in a mix which was very high in clay content, causing the cracks you see in the photo below.

Here I didn't put in enough sand and you can see the results here. Excess clay is causing shrinkage and lots of cracks.

Here I didn’t put in enough sand and you can see the results here. Excess clay is causing shrinkage and lots of cracks.

Later on in the wall, I managed to get the correct mix, and as a result, the wall is smooth and has no cracks.

This mix was a good one - uniform, smooth and no cracks.

This mix was a good one – uniform, smooth and no cracks.

In the future, I should always remember to mix a decent test batch and actually write down my mixes! A scales would be a good idea to measure batches rather than just using a bucket as a rough measure…

The cracks shouldn’t cause me too much grief though. I’m patching them up with a new (decent!) mix tonight, so you wouldn’t even know!