Before moving on with any further testing I realized there was an important question that needed to be resolved. Having demonstrated casting artifacts and how to prevent them I realized I needed to address the question of whether or not real dermal ridges could even be recorded in a print and subsequently documented in plaster.
I realize this is a bridge that's been crossed before (just like the original issue of artifacts) but this blog is the documentation of an ongoing process and ignoring this question would be like leaving out the D-F section of an encyclopedia.
Apologies to those who have been waiting for this installment of my blog. This particular test required me to raise my photography game to a new level in order to properly document the results. I certainly hope you feel it was worth the wait.
As always the testing begins with a proper layer of ash. Since my test foot (or the recently dubbed Big Green Foot) has no dermal ridges of its own I had to set it aside for this test. A pair of impressions were made using my own hands. I had originally planned on testing two different things for this test (hence the two hands) but made an error in creating the second print. Hence the presence of left and right hand prints with only the focus on the right.
A barrier spray was applied to the right print. As in the barrier spray test three layers were applied with each layer drying for 15 minutes. Once the barrier spray was set a sufficient amount of plaster was prepared. The plaster was mixed to the same ratio and in the same manner as previous tests. The plaster was then poured directly into the right hand print.
The plaster was allowed one hour to set. After removal from the ash bed it was given 24 hours to cure before being cleaned.
After a thorough cleaning it was evident that numerous features had been recorded by the plaster. The distal palmer crease along with all distal interphelangeal, proximal interphelangeal, and palmar digital creases had been recorded. Several smaller creases had also been recorded. Most importantly, the plaster had captured my fingerprints.
The above photo and inset are from the distal phalanx of my index finger.
On a whim (and at the advice of a good friend) I decided to employ my Sirchie fingerprint kit to attempt and bring out the print detail to a greater degree. If nothing else it gave me a good excuse to knock the dust off it and get in a little practice.
After dusting the cast a series of documentation photos were taken. To ease up on bandwidth I'm presenting just one here to demonstrate the difference in photographic clarity between the undusted and dusted print.
All in all this was a very simple test but I think it illustrates a good point. In a controlled setting using an ultra fine substrate dermal features were succesfully recorded by my plaster cast. The real world settings are a different matter entirely, but at least the ability of the plaster itself to record such fine features can be firmly established.
