The resin issue

During this week, I was able to finish CT scanning, which is something I was looking forward to get done. I believe one of the most challending thing I will have to do while here is going to be analyzing the CT scans, since I will have to use a software I am unfamiliar with, and the work itself is pretty delicate since we want to slice the different tissues on the leg. After all of the heavy work of putting the legs in resin, sawing them and filing them, we were finally ready to take them to the micro-indenter machine, housed across the university. The idea of  indentation is quite ingenious: figuring out a material's hardness by testing it against a material of known properties. The leg parts encased in resin were very small depending on the species, which made loading them perfectly even on the machine quite challenging. We started by using the last segment of a femur of Pachylis pharaonis, which you might not know, but is absolutely huge. The process starts with finding the cuticle on the microscope, choosing the spot to indent, and then turning on the machine. Once indenting is done, we measure the height and the width of the mark, which is done using a lozenge-shaped diamond tip, then the machine automatically gives you measures of hardness and strength. The first leg was a trial. We had to figure out what the optimal time for indenting was as well as the weight. We want to keep this consistent across all legs, so it is important to ensure that we have a strong grasp of what the best parameters are. Moving on to another segment of the same leg, we found that it was not filed perfectly even and straight, which can mess up the results. We do not have the best materials to ensure we're filing the legs perfectly even, such as a machine that the people that work with indenting metals might have, so we had to figure out a way to maximize the quality of our resin blocks to attain accurate results. Even more importantly, we found something else. The resin somehow made its way inside the cuticle tissue. My mentor, Alexandre, had used this method before with no issue, and we used high viscosity resin to avoid exactly this happening. Upon checking the other legs, we realized that close to all of them had resin on the inside of the cuticle. We even brought it up to a high power microscope to check it out. We could see that the resin was all over the insides of the cuticle, which made no sense (see attached image). Alexandro consulted some of his colleagues that used similar methods and confirmed that we seem to have done everything right. Brainstorming some issues that might have led to this, I came up with a few things. We did not know the age of most of our specimens, and maybe the structural integrity of the cuticle was not good to start with, facilitating the entrance of resin. Besides that, some legs, particularly the bigger ones, wouldrise inthe resin (due to their size and age), and so I would have to push them down to ensure they were submerged . This could have made it easier for the resin to enter through the cuticle. We're still not sure what went wrong, since what we did was supposedly meant to circumvent those issues. But nothing is perfect, much less when doing science. Some solutions we thought of were to use some fancy resin with the highest viscosity we could find, and we would try to double layer to rise into avoid pushing down the leg. This issue was a major setback as it took me nearly a wig to finish encasing cutting and filing all the legs.