3.2.2. Shrinkage and Weight Reduction of Cylindrical Specimens Grown for Compression Testing

The shrinkage of the specimens was calculated for the entire manufacturing process. Detailed data about the shrinkage of the cylindrical specimens are shown in Appendix I. For these specimens, the mycelial growth process lowered the initial weight by 5% (Table A1). The specimens had to be slowly dried before applying the post-growth treatments. This step was necessary because post-growth treatments were applied in a non-controlled environment (i.e., warehouse) where specimens were exposed to various contaminating species. Furthermore, the materials were stuck inside their mold at the end of the growth process and could not be extracted without damaging them. Therefore, the cylindrical specimens were kept inside their mold during the drying period. This drying process reduced the weight of the specimens to 50% of their original weight. The compaction process did not significantly affect the weight of the specimens. The drying and baking treatments finally brought the weight of the materials down to around 22% of their initial weight at inoculation.

In terms of height, the growth process did not significantly modify the specimens' height. The drying period lowered their height by around 5%. After this drying period, the specimens were cut to a height of 11 cm. Therefore, the rest of the height evolution was considered to start with 11 cm equaling 100% at this stage. Compacted specimens were mechanically compacted to half of their height (i.e., 50% or 5.5 cm). Then, the baking and drying treatments reduced their height to 49.5% before testing. For the uncompacted specimens, the drying/baking process only reduced their height by around 0.3%. Therefore, there was a mean height shrinkage of 5.4% for the cylindrical specimens.

Shrinkage also happened horizontally (i.e., to the diameter of the cylindrical specimens). No shrinkage was observed during the growth period (Table A1). The drying period prior to post-growth treatments shrank the 17 cm high specimens (i.e., uncompacted) by an average of 3.24% An additional 0.28% diameter shrinkage was observed during the drying/baking process. The compacted specimens were compacted inside their PVC molds used during the growth period. Compaction treatment increased the specimens' width to their original width by pressing the material against the inner surface of the molds. The specimens were removed from the molds for the baking/drying process. During this process, their diameter increased by around 5.31%. Therefore, only uncompacted specimens should be used to estimate the shrinkage observed in cylindrical specimens. The total shrinkage from inoculation to the beginning of mechanical testing would then average 3.52%.

### 3.2.3. Shrinkage and Weight Reduction of Panel Specimens Grown for Bending Testing

Compared to the cylindrical specimen analysis, the high level of contamination made the weight study inconclusive. The uncompacted specimens' height shrank by around 9.29% when considering all specimens (Table A2). The height of the compacted specimens was reduced by 62.68% during the entire process, including the compaction post-growth treatment. Knowing that the compaction post-growth treatment accounted for 50% of this height reduction, an average shrinkage of 12.68% was observed. In terms of horizontal shrinkage, the width of the uncompacted specimens was reduced by around 4.93%. The length shrinkage, however, could not be calculated because uncompacted specimens had to be trimmed due to contamination. Additional data about the shrinkage of the rectangular specimens are shown in Appendix I.
