Founder, Gayle Parsons, sums up the Summer Print week by week.
WEEK 4
This week we continued to prepare material, grinding earth and creating a large store of sieved earth for batch printing later in the week. Thanks are certainly due to the two volunteers with us this week, Basama and Izzy, who worked their socks off getting the earth prepared.
The sieve system started to fail, however, and we had to start using the hand sieve again to ensure no small stones got in which could damage the pump. Adam came to the rescue later in the week and built us a new sieve system, more robust, 3mm mesh/hole size which worked much better.
The leaf blower proved to be a good solution to chopping the straw. Even so, we had to put the straw through the system at least 5 times before it reached the required length (5cm), and realised after the pump paddles became blocked during printing that even this was not enough, so we re-chopped all that we had done another 3 times (total 8 times through the leaf blower!).
It has become crucial to define our minimum earth to water ratio before moving forward with any other additives. So a lot of time was spent trialling different earth to water ratios through the pump – with no hose attached – just to see if it was pumpable. Mixing these rather dry mixes was hard work but essential to give us a base line from which to build on.
There was much discussion about the difference between ratio and percentage, and Megan spent a lot of time trawling through past published papers looking for evidence from other studies on mix recipes. Our soil has a high clay content (approx 40%) so we must add sand to balance it out. We noted from Sandy Curth’s (MIT) paper that soaking our mix for several days before trying to print with it helped the clay to homogenise, and prepared 4 batches of mix with different earth to water ratios, ready for next week.
