The Testimony of Perry Tuttle of US Gypsum

     The bulk of the following essay, and the ensuing discussion, originally appeared here.

     Recently an associate of mine sent me a link to a blog entry of an individual thought of throughout the subculture of Bigfootery as a groupie, and one prone to false accusations if not outright lies.

     Amazingly, after all this time, this individual finally follows the simple directions I suggested more than 2 years ago and gets exactly the results I suggested would occur:

     In fact, the result is a rather striking match for the texture we see 9cm anterior of the heel on CA-19:

     At this point, the rational and scientifically minded person would simply say, “Wow, it looks just the same, and nothing like real dermal ridges”
     But no, The Groupie has to go through conniptions to explain away the obvious match. She decides it’s all my fault because at one time I used chopsticks to mix my plaster slurry! She equates this to a wire whisk and implies that the ridge artifacts are due to entrained air!
     First off, this is a direct personal attack against me, as it implies I’m utterly incompetent to even mix plaster of Paris. A baseless accusation of course, but by now this is common practice for The Groupie.
Ever notice how The Groupie never names the experts she claims to consult? Ever notice how The Groupie never records or publishes the correspondence she has with these experts? It’s always phone calls, and second hand anecdotes. We see it in her blog entry:

In this specific situation, had I payed more attention to the expert with USGypsum.com, this may not have gone on so long. Instead I allowed myself to be bogged down in arguments over water temperature and pancake batter. I should not have doubted this man from USGypsum.com's 25 years of experience with this product he has such an incredible knowledge of. We really should listen to those who have expertise in areas, especially when that expertise or knowledge can help us.

     Who is this expert? What is his name?
     To cut to the chase, I knew that her claim that the ridges we see are due to entrained air is complete and total bullshit. There are a bunch of reasons for this.

1. If these ridges were due to entrained air, we would see them on every substrate, but we don’t.

2. We don’t see them on casts made in substrates that have had a proper application of a barrier spray.

3. We don't see them occur on non-porous surfaces, like latex molds.

4. Entrained air produces little pits, not ridges! And so on…

     But hey, why listen to me, I just have a Bachelor of Science degree in Pharmacy. I decided to follow up with The Groupie’s source of information; US Gypsum.

     I sent the following e-mail to Kym Heitke, a technical representative with US Gypsum:
Hello, my name is Matt Crowley, and I’m writing from Seattle Washington. For some time now, I’ve been investigating a strange property of some of your casting compounds including Ultracal 30, Hydrocal B11, and ordinary plaster of Paris. When I make casts of impressions made in certain fine, dry substrates like pumice or silica without a barrier spray, I sometimes get very characteristic ridges and furrows. For some time now, I’ve been trying to understand the mechanism of this process. An associate of mine with a PhD in Geology advises me that they are “desiccation ridges”, caused by the strong capillary action of these particular substrates pulling the water from the cement slurry strongly away. To understand on a visual level what I’m talking about, I’ve created a number of webpages on the subject. Here is a good example:

http://www.orgoneresearch.com/testing_silica.htm

I fully recognize the subject of “Bigfoot” is “fringe science” but I assure you the spontaneous ridge phenomenon is absolutely real and easily reproduced. I appreciate you taking the time to read and respond to my request, which is simply this; can you help me to understand the physical mechanism that would produce these spontaneous ridges?

I’m usually home from work after about 4:00 o’clock if you want to call me at home. My home phone number is 206-XXX-XXXX

     I didn’t get a response from Kym Heitke, but she forwarded my e-mail to Perry Tuttle, who has given me permission to publish his answers to my question. Here is his response to my first e-mail:

Matt,

It appears to me that your geology friend is correct. The porous nature of the material you are making the impression in is "wicking" water at uneven rates from the plaster. To rehydrate plaster properly, the slurry needs to lay undisturbed after vigorous mixing. If wicking is occuring, the suspended solids compact due to the water being withdrawn, and that creates ridges and water starved (desication) cracks on the cast.

Since this has happenned on various USG products of a wide range of formulation difference, I'm pretty confident. Also, if the dessication and ridging does not occur after you "seal" the pumice or fine silica impression, then that supports a wicking problem. We recommend to seal any surface that plaster is poured against.

Here is something to try if you don't seal the impression before pouring plaster. First, mix the plaster vigorously for at least five minutes - this will ensure that the plaster crystals are already using the water before you pour. This will also create a faster setting plaster which could solidify before the full effects of wicking take hold. I believe the fix is to use a sealer on your "mold".

We have a good website called gypsumsolutions.com that has great literature on mixing, casting, drying, etc. to help you read up on the details.

Perry Tuttle
Region Sales Mgr-West
Performance Substrates, USG

     Imagine that! A technical expert at US Gypsum agrees with what Anton Wroblewski, a PhD in geology and therefore an expert in inorganic processes has been saying all along: these are DESICCATION RIDGES! Who would have thought!

I sent Mr. Tuttle another e-mail:

Mr. Tuttle;

Thank you very much for responding to my e-mail inquiry. I was fairly confident that slurry desiccation was the most likely mechanism involved in this process, and I’m glad to have received your confirmation. As a follow-up, I have read a public claim that the ridge-artifacts are due to entrained air, and not desiccation. I don’t believe this to be correct for a number of reasons, the least of which is that I’ve never seen little bubble-pits on any of the ridges in any test casts I’ve made. I’d like to get your take on this claim as well.
In addition, I would like your permission to publicly quote your answer, as well as this portion of your previous e-mail:

Matt,

It appears to me that your geology friend is correct. The porous nature of the material you are making the impression in is "wicking" water at uneven rates from the plaster. To rehydrate plaster properly, the slurry needs to lay undisturbed after vigorous mixing. If wicking is occuring, the suspended solids compact due to the water being withdrawn, and that creates ridges and water starved (desication) cracks on the cast.

His response:

Hi Matt,

It’s fine to post my opinions. Air entrainment problems, when created by poor mixing practices, tend to show up throughout a cast and do not create one isolated feature. Many times, when a mold has a particular section of contour where air can’t be fully displaced to the backside (top) of the casting, then you can get isolated air entrained features. In both cases, you should see air bubbles in cross section.

Additionally, pouring a plaster product against a porous medium can also create bubbles even though you may have mixed the slurry without entraining air. When the slurry enters an open porosity system, the air has to be pushed out somewhere and typically, it will simply find its way into the slurry. Sealing your pattern material is the way to go.

Perry

     As you can see, NOWHERE does he suggest that these ridges are due to air entrainment , and in fact accepts the mechanism proposed by Dr. Wroblewski: desiccation.

     Perhaps it's time for The Groupie to reconsider her constant resorts to anecdotal, second-hand accounts of unnamed individuals whom she claims to be experts. Since she has demonstrated time and time again that she has no clue what real science is all about, perhaps she should consider a move to the UFO field, where second hand accounts from unnamed and secret sources is standard operating procedure. The UFO field is rife with personalities like hers; I'm sure she would fit right in.

     Dermal Ridges and Casting Artifacts

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Fake Feet and Monolithic Margins

     Pressure Releases and Scalloped Margins