Evidenciary Forensics Collection Methods, Tricks and Tips of the Trade Options

[longtabber PE]

And people wonder why we are beat up and called unprofessional.

This is why. You are using outdated information - I say outdated, because people stopped using chicken wire in casting material a very long time ago for this, hell Im shocked you didnt recommend the use of a popcicle stick.

I think it is you who does not know what your talking about. As my methods have proven results, and I have only seen artifacts when I deviate from the methods I discussed in this thread.

>>And people wonder why we are beat up and called unprofessional.

no "people' dont

>>>This is why. You are using outdated information - I say outdated, because people stopped using chicken wire in casting material a very long time ago for this, hell Im shocked you didnt recommend the use of a popcicle stick.

you are arguing nothing ( other than for the sake of arguing) because heres reality- no support membrane is going to "rust" unless either chemicals or oxygen attack it ( thus the term oxidation) and casting compounds are mostly inert ( as compaired to cements) There are structure here and now that have held up for CENTURIES with the described methods.

CW is cold galvanized and resistant as well as suitable for the application- you are arguing 'longevity" as if it means something ( it doesnt)

>>I think it is you who does not know what your talking about. As my methods have proven results, and I have only seen artifacts when I deviate from the methods I discussed in this thread.

First of all, you dont have the knowledge or experience to even voice an educated opinion here- you are just parroting word from others and you are letting your ego prompt your speech.

You dont even know what an "artifact" is- much less how to avoid one ( thus the initial thread and the prep work)

"your" methods have produced cast replications of a hole in the ground and nothing else

[wolftrax]

Yes, that is in essence exactly what I said - right up until the mixing. How many researchers in the field carry with them a high-speed, direct drive propeller mixer - hell, how about just the juice to run it in the field??

Which is exactly why hand mixing in this situation is the best alternative. Using anything smaller than a paddle or your hand will create too many air bubbles - and give you artifacts.

I'd actually like to see something to support this.

I think it is you who does not know what your talking about. As my methods have proven results, and I have only seen artifacts when I deviate from the methods I discussed in this thread.

I take it you have yet to use that pumice you purchased.

[Bitter Monk]

6) samples exposed to direct sunlight or extreme moisture or more than 30 days old ( applying to samples outside in the woods) are probably not worth collecting

This one is particularly interesting to me for reasons I'd rather not get into at the moment. Is 30 days the cut off for objects sheltered from the weather, and if so what would be the estimated cut off for objects exposed to light and moisture?

you are arguing nothing ( other than for the sake of arguing) because heres reality- no support membrane is going to "rust" unless either chemicals or oxygen attack it ( thus the term oxidation) and casting compounds are mostly inert ( as compaired to cements) There are structure here and now that have held up for CENTURIES with the described methods.

I was going to ask about entrapped air causing casts to break during altitude changes during shipping, but in hindsight if the cast is prepped and poured correctly it would seem that wouldn't be an issue.

[Melissa]

FBI

Mixing Dental Stone in a Bag
Store dental stone in resealable plastic bags. An 8-by-12-inch resealable plastic bag can store two pounds of dental stone powder. With premeasured bags, casting impressions at the crime scene involves only adding water. The bag containing the dental stone powder can be used to mix and pour the dental stone.

To make a cast, add the appropriate amount of water to the bag and close the top. Mix the casting material by vigorously massaging it for 3-5 minutes through the bag. Ensure that the material in the corners of the bag is also mixed. After mixing, the material should have the consistency of pancake batter or heavy cream.

Mixing Dental Stone in a Bucket or Bowl
If the impressions are numerous or large, it may be necessary to mix larger quantities of dental stone in a bucket or bowl. The dental stone should be slowly added to the water and continuously stirred for 3-5 minutes. After mixing, the material should have the consistency of pancake batter or heavy cream.

So, apparently the FBI is using substandard methods as well. They forgot their electric mixer....

Regardless of the Casting Agent - the mixing procedures remain the same.

This post has been edited by Melissa: Nov 28 2007, 07:33 PM

[longtabber PE]

This one is particularly interesting to me for reasons I'd rather not get into at the moment. Is 30 days the cut off for objects sheltered from the weather, and if so what would be the estimated cut off for objects exposed to light and moisture?
I was going to ask about entrapped air causing casts to break during altitude changes during shipping, but in hindsight if the cast is prepped and poured correctly it would seem that wouldn't be an issue.

>>This one is particularly interesting to me for reasons I'd rather not get into at the moment. Is 30 days the cut off for objects sheltered from the weather, and if so what would be the estimated cut off for objects exposed to light and moisture?

I specifically asked the question ( as you posed) and the 'correct' answer is that there is no answer ( too many variables and possibilities)- her answer to me was a "rule of thumb" ( based on her experience and publications)- the bottom line, if you have a sample- test it and see, but after the effects of weathering, dont be overly hopeful about positive results.

>>>I was going to ask about entrapped air causing casts to break during altitude changes during shipping, but in hindsight if the cast is prepped and poured correctly it would seem that wouldn't be an issue.

its literally impossible to remove all entrained air from any aggregate, pouring ( unless you slop it) doesnt entrain air- you mixe it good and agitage it good- you will be fine

[Bitter Monk]

its literally impossible to remove all entrained air from any aggregate, pouring ( unless you slop it) doesnt entrain air- you mixe it good and agitage it good- you will be fine

That's what I was thinking. I imagine I would still err on the side of caution and use ground shipping.

In your experience, or in consulting with others, is there anything you would add regarding a splash or dual stage casting?

[wolftrax]

Using anything smaller than a paddle or your hand will create too many air bubbles - and give you artifacts.

What's your source on this?

[Melissa]

Click the link and find out.

FBI.gov - its right in the post wolftrax.

In case you missed it.

http://www.fbi.gov/hq/lab/handbook/intro14.htm#casting

Oh, and apparently your not familiar with the joy of the ziplock bag. They keep air out.

Im done with this. Enough bad information has been given out on this topic.

This post has been edited by Melissa: Nov 28 2007, 07:45 PM

[longtabber PE]

So, apparently the FBI is using substandard methods as well. They forgot their electric mixer....

Regardless of the Casting Agent - the mixing procedures remain the same.

Once again, you let your ego and arrogance get in the way of the subject matter

there is the "book" ( which has been updated) and what works BEST ( remember FIELD methods may in fact be impromptu)

BTW- WHO do you think told the FBI the way? ( the people who make it)

can you not understand the very simple difference between the "textbook" method and more 'advanced" methods ( as i was describing?)

What kind of point are you trying to prove? YOU asked for help. YOU are the one who has actually produced NOTHING, YOU are the one who wants to better things.

Nothing I have put here is less than Industry standard and factually correct, yet you STILL whine and try to sharpshoot ( which was ineffective but entertaining)

Why is that? Are you seeking some form of absolution that makes all your substandard and ineffective methods OK? Are you trying to make mediocre into state of the art?, Are you trying to make excuses for failed attempts so egos and agendas can be salvaged?

Or is it simply a bruised ego from arguing such things as the lagality of defense of property, use of screwboards, repo people and a 'right' to shoot trespassers in Texas and having been proven wrong in all of the above?

its obvious you have no techincal knowledge about the subject and are just parroting words- so why are you arguing with those who know what they are talking about? Wasnt it you days ago WANTING to know WHY things "failed" and was asking for answers? You GOT answers ( which are correct) and now you whine more- whats up with that?

If you "knew'all the answers, you wouldnt be doing so much WRONG ( or less than the best methods available)

[longtabber PE]

That's what I was thinking. I imagine I would still err on the side of caution and use ground shipping.

In your experience, or in consulting with others, is there anything you would add regarding a splash or dual stage casting?

From the prefect world scenario

in the prefect world- you would want a thin layer of media from bulb or aspirator or spreaders to cover any important features- THEN pour ( this is what you are describing as stages- stage 1 is for detail, stage 2 is for strength)

Universally, 'splash" is the WORST thing to do ( when you want detail)

the only "rule of thumb" is this

there is air in both the substrate as well as being captured between the substrate and the pour- do everything you can to minimize that ( spread in place for detail) then a GENTLE pour

[Bitter Monk]

Im done with this.

This thread has the opportunity to be a great Q&A session with someone who, like him or lump him, obviously has good pertinent information to share. Perhaps instead of having a contest to see who has the highest high horse we should instead be trying to have a meaningful discussion that might actually further us along (which is something everyone claims to want).

[longtabber PE]

Oh, and apparently your not familiar with the joy of the ziplock bag. They keep air out.

Im done with this. Enough bad information has been given out on this topic.

Thats good you are done with this- now we can get back to sharing valuable and useful information- you were quite a distraction.

I hope you will learn something- even if by accident

[wolftrax]

Click the link and find out.

FBI.gov - its right in the post wolftrax.

In case you missed it.

http://www.fbi.gov/hq/lab/handbook/intro14.htm#casting

Oh, and apparently your not familiar with the joy of the ziplock bag. They keep air out.

Im done with this. Enough bad information has been given out on this topic.

Uhhhh, yeah, I'm not seeing anything in that link about using anything smaller than a paddle to mix your plaster causing artifacts. It's not saying to use your hand either. I guess you still haven't used pumice. Anyways, good to see the bad information won't be given out anymore.

This post has been edited by wolftrax: Nov 28 2007, 08:35 PM

[Bitter Monk]

in the prefect world- you would want a thin layer of media from bulb or aspirator or spreaders to cover any important features- THEN pour ( this is what you are describing as stages- stage 1 is for detail, stage 2 is for strength)

Not to say that you're getting over my head but... whoa. "Bulb"? "Aspirator"? What exactly would these be and how would I fit them in my field pack?

[the evilist sere...]

This is surreal.

QUOTE( Melissa)
"Using anything smaller than a paddle or your hand will create too many air bubbles - and give you artifacts."

QUOTE( wolftrax)
"What's your source on this?"

QUOTE (Melissa)
"Click the link and find out.

FBI.gov - its right in the post wolftrax.

In case you missed it.

http://www.fbi.gov/hq/lab/handbook/intro14.htm#casting

Oh, and apparently your not familiar with the joy of the ziplock bag. They keep air out.

Im done with this. Enough bad information has been given out on this topic."

***

I'm at the link, I'm missing it, it's not mentioning "paddles" and "hands" (but rather "sticks" and "fingers"), it's not mentioning these "stirrers" as the first stir choice, and so on. I am missing something, but I think I've got your link correct? As of 6 months ago I was caught up with those who cast and their detailed "methodology" reports ... but I never read anything about anyone using colored dental stone, plastic bags for mixing (and Ziplocks<r> only keep out air if the caster or kid packaging his sandwich gets the air out in the first place), and pouring casting material into water. So are the techniques below the ones you're using from A to Z, Melissa? If not, it would be great clarifying information on which techniques you use, the source of each technique, and how your expertise has led to the combo you've come up with. Thanks ... Dana.

***

http://www.fbi.gov/hq/lab/handbook/intro14.htm#casting
Casting Three-Dimensional Impressions
Casting a three-dimensional impression in soil, sand, or snow is necessary to capture detail for examination. Dental stone, with a compressive strength of 8,000 psi or greater, must be used for casting all impressions. The compressive strength is listed on the container along with the proper ratio of powder to water used for mixing. Dental stone is available through local dental supply houses. Colored dental stone is preferred.

Plaster of Paris, modeling plasters, and dental plasters are not sufficiently hard, do not resist abrasion when cleaned, and must not be used.

Mixing Dental Stone in a Bag
Store dental stone in resealable plastic bags. An 8-by-12-inch resealable plastic bag can store two pounds of dental stone powder. With premeasured bags, casting impressions at the crime scene involves only adding water. The bag containing the dental stone powder can be used to mix and pour the dental stone.

To make a cast, add the appropriate amount of water to the bag and close the top. Mix the casting material by vigorously massaging it for 3-5 minutes through the bag. Ensure that the material in the corners of the bag is also mixed. After mixing, the material should have the consistency of pancake batter or heavy cream.

Mixing Dental Stone in a Bucket or Bowl
If the impressions are numerous or large, it may be necessary to mix larger quantities of dental stone in a bucket or bowl. The dental stone should be slowly added to the water and continuously stirred for 3-5 minutes. After mixing, the material should have the consistency of pancake batter or heavy cream.

Pouring Dental Stone
Casting material has sufficient weight and volume to erode and destroy detail if it is poured directly on top of the impression. The casting material should be poured on the ground next to the impression, allowing it to flow into the impression. The impression should be filled with casting material until it has overflowed.

If the mixture is too viscous to flow into the impression, vibrate a finger or a small stick on the surface to cause the dental stone to flow into the impression. Do not put the stick or finger more than 1/4 inch below the surface of the casting material because it can damage the impression.

Before the cast completely hardens, write the date, collector's initials, and other identifying information onto it. The cast should be left undisturbed for at least 20-30 minutes in warm weather. In cold weather, the cast should be left undisturbed longer. Casts have been destroyed or damaged when lifted too soon. If the cast is in sand or loose soil, it should lift easily. Casts in mud or clay may require careful treatment and excavation when being removed.

Allow the cast to air-dry for at least 48 hours. Package the cast in paper, not in plastic. A Laboratory examiner must clean the cast.

[longtabber PE]

Not to say that you're getting over my head but... whoa. "Bulb"? "Aspirator"? What exactly would these be and how would I fit them in my field pack?

a "bulb" is what "looks like' a baster (squeeze bulb with a nozzle) and it "spits"

Aspirator is similar but looks like a spray bottle


The idea is to place the contact layer GENTLY ( from top to bottom) rather than lateral movement ( which could distort detail)

in any casting- the ONLY thing you are after is the surface detail- anything else is support

[Bitter Monk]

So, and just to make sure that I've got this right.

After thorough mixing of the material and prepping the track, a person would...

A - Fill the bulb with material

B - Apply by vertical "spits" instead of lateral pours (or spray via an aspirator*).

C - Establish a base coat covering all the surface detail using the "spit" method.

D - Pour a backing mold.

Correct?


* - Do you know of any small, compact aspirators that would be easily included in a pack?

[HarryHenderson]

Not to say that you're getting over my head but... whoa. "Bulb"? "Aspirator"? What exactly would these be and how would I fit them in my field pack?

You're gonna have to make a choice son. Give up taking all those battery driven 'marital aids' along and start packin' actual Bigfoot Investigation Paraphenalia™...sheesh!

[longtabber PE]

So, and just to make sure that I've got this right.

After thorough mixing of the material and prepping the track, a person would...

A - Fill the bulb with material

B - Apply by vertical "spits" instead of lateral pours (or spray via an aspirator*).

C - Establish a base coat covering all the surface detail using the "spit" method.

D - Pour a backing mold.

Correct?
* - Do you know of any small, compact aspirators that would be easily included in a pack?

The process is correct

we always used a bulb ( aspirators were for boundary agents, release agents) let me check and verify if aspirators exist for viscous liquids ( that would conflict with the term aspirator and I think I may have had a run on thought upthread- I may have used the terms incorrectly- if i did, I'll correct it)

I'll get back with you but the ones we has were about 6" and fit nicely in a pack ( we used cake decorating equipment) I also remember ( in training) using a bag with a tip cut off ( like decorating a cake with icing)

It doesnt matter what tool is employed- what matters is a top down gentle pour to cover the detail. After that, its just filling

You're gonna have to make a choice son. Give up taking all those battery driven 'marital aids' along and start packin' actual Bigfoot Investigation Paraphenalia_..sheesh!

shhh but the secret is to have a battery that fits all

[Bitter Monk]

You're gonna have to make a choice son. Give up taking all those battery driven 'marital aids' along and start packin' actual Bigfoot Investigation Paraphenalia_..sheesh!

How else do you expect me to vibrate the entrapped air out of the mix?

[nightwing]

How else do you expect me to vibrate the entrapped air out of the mix?

Somewhere out there..someone is thinking "you know..that's really NOT that bad of an idea!"

[dogu4]

That plastic bag method is slick. I've had to mess with plaster bunches in the past and I gave it a try on a quick home job where I needed a pint of plaster and provided you're sensible about the way you add the water and the dry mix so that slaking will occur (the plaster must be saturated to the correct degree), mixing gently by squishing doesn't entrain any air especially if you squeeze it out of the ziplock before you seal it...I then cut off a corner to apply to the space I was filling, but opening the zip for wide access would be a natural thing. It also eliminates a trashcan full of problems when doing this away from a workshop...pre-measure it....
Which brings to mind something not mentioned. My experience with plaster sometimes had to consider the tiny amount of shrinkage...it could be critical on certain jobs and so certain plasters were needed with specific coefficients and those were dependent on both the method of application and the precise water to plaster proportions. I don't know if this applies to getting a successfull cast, in fact I know it doesn't for most stuff, but it would be negligent scientifically to not capture that in any analysis on the dimensional aspects....etcetera.

[damndirtyape]

The process is correct

we always used a bulb ( aspirators were for boundary agents, release agents) let me check and verify if aspirators exist for viscous liquids ( that would conflict with the term aspirator and I think I may have had a run on thought upthread- I may have used the terms incorrectly- if i did, I'll correct it)

I'll get back with you but the ones we has were about 6" and fit nicely in a pack ( we used cake decorating equipment) I also remember ( in training) using a bag with a tip cut off ( like decorating a cake with icing)

It doesnt matter what tool is employed- what matters is a top down gentle pour to cover the detail. After that, its just filling
shhh but the secret is to have a battery that fits all

Maybe you could show us a cast you have made using your method. I for one would be really interested in seeing the surface textures obtainable this way. Most tracks I have casted used between 10 and 17 lbs of plaster and the manufacturer recommends that for satisfactory results you pour plaster into water and not the other way around.

This post has been edited by damndirtyape: Nov 28 2007, 09:38 PM

[longtabber PE]

Maybe you could show us a cast you have made using your method. I for one would be really interested in seeing the surface textures obtainable this way. Most tracks I have casted used between 10 and 17 lbs of plaster and the manufacturer recommends that for satisfactory results you pour plaster into water and not the other way around.

First of all, pay attention to detail and it may help your casting technique- I NEVER said pour water into the media- now that we have solved that.

I dont cast 'tracks" ( not in recent history anyway) but I have worked on castings from alternator /starter housings to pistons with tolerances into the thousandths and finishes into the microns.

So what do you need to know or tell me what you are doing and I"ll be happy to assist you in advancing your technique and help you get better ones.

I'll ask you- you obviously have plenty of representations of "holes' in the ground- what have you gleaned from them thats 'earth shattering' or definitive? If your answer is ZERO, then let me know and lets see if we can fix that using better and more advanced methods.

[Hominid,WA]

First of all, pay attention to detail and it may help your casting technique- I NEVER said pour water into the media- now that we have solved that.

I dont cast 'tracks" ( not in recent history anyway) but I have worked on castings from alternator /starter housings to pistons with tolerances into the thousandths and finishes into the microns.

So what do you need to know or tell me what you are doing and I"ll be happy to assist you in advancing your technique and help you get better ones.

I'll ask you- you obviously have plenty of representations of "holes' in the ground- what have you gleaned from them thats 'earth shattering' or definitive? If your answer is ZERO, then let me know and lets see if we can fix that using better and more advanced methods.

Easy pal. I'd tread with some caution here, otherwise any worthwhile points you bring up on this board will get lost in your pretentiousness.

[longtabber PE]

Easy pal. I'd tread with some caution here, otherwise any worthwhile points you bring up on this board will get lost in your pretentiousness.

Under normal circumstances i would agree ( then again, under normal circumstances, I wouldnt have made such a post)

Its not pretentiousness, I can assure you.

[Blackdog]

Yeah that would suck if we actually learned how to do something better, the results up to date have been far less than conclusive no matter what your definition of conclusive is.


Don't tread on me


This post has been edited by Blackdog: Nov 28 2007, 10:56 PM

[Bitter Monk]

Is that Saint Udderus or Saint Bovinous?

[JohnCartwright]

Kewl..this Longtabber guy is taking all the heat off of me.

[damndirtyape]

First of all, pay attention to detail and it may help your casting technique- I NEVER said pour water into the media- now that we have solved that.

I dont cast 'tracks" ( not in recent history anyway) but I have worked on castings from alternator /starter housings to pistons with tolerances into the thousandths and finishes into the microns.

So what do you need to know or tell me what you are doing and I"ll be happy to assist you in advancing your technique and help you get better ones.

I'll ask you- you obviously have plenty of representations of "holes' in the ground- what have you gleaned from them thats 'earth shattering' or definitive? If your answer is ZERO, then let me know and lets see if we can fix that using better and more advanced methods.

Casting against metal or other non-porous substrates is quite different. It is also a fact that weather plays a big part in what your plaster does. Temperature, sunlight contact and humidity are usually controlled in industry.

I haven't really had a problem in the casting part of this effort. Been using the material and industrial tooling standard practices since the mid 70's... daily. Microns huh!?

Pretty sure of your self I see. Just read the entire thread here and see no advanced methods proposed by you, only impractical ones. By the time you got enough plaster mixed and into a baster/bulb apparatus it would be kicking. The thicker the plaster mix the less surface detail (unless you are casting metal or some other non-porous substrate). Thicker plaster will fold over itself and create artifacts. Spread out over a surface; plaster dries quicker then in chemically cures. Placed in a compact volume container the opposite is true. Then you have to clean the baster/bulb. I won't even go into the chicken wire stuff as others already mentioned it. Arresting surface particle movement is problematic and with most tracks unnecessary since they were made in moist soil conditions. Snow wax is ok to use but not really necessary either, if you know what your doing. It would have been more important for you to have mentioned at what water temperatures you do all of these advanced techniques at.

Your postings remind me of someone else on the board but from the past.

[SgtFang]

Here's an aspirator, AKA "Snot sucker"



These can be found in the baby aisle of pretty much any store.

-Sarge

Rick, what do you think of moving up to a high grade silicone for track casting? Granted it's a lot more expensive, but it'll capture fingerprints on a sheet of glass too.

-Sarge

[Hominid,WA]

Yeah that would suck if we actually learned how to do something better, the results up to date have been far less than conclusive no matter what your definition of conclusive is.
Don't tread on me

I'm all for learning on this forum, but if someone doesn't keep his cool, he's eventually gonna go bye-bye. (we've seen it happen to others here before) Nothing can be learned from snide remarks that don't foster further progressive dialogue, especially to seasoned researchers he has yet to converse with. It automatically puts the recipients on the defensive, and not much can be learned from that. Since you Blackdog, seem so strongly to have taken up the sidekick role here, might you persuade him?

In response to the photo you've posted, I do have a picture of my own, and if I may..... red's definately not your color.

[uffda320]

I'm enjoying reading LT's posts. I think it's great to have a new person onboard, with a new way of looking at this mystery.