Ninhydrine Steaming

[Ernie Hamm]

In my seemingly endless task of eliminating various paper and publications I accumulated over the years I came across something with a technique of interest, one which I never recall hearing discussed or utilized in my laboratory experience. It was found in the article “Ninhydrine Combats Bank Frauds” by Olli Rispling (Stockholm C.I.D.), published in ‘the criminologist’, 6:22 (Autumn 1971). I will use Inspector Rispling’s ninhydrine term for this posting.

The article discusses an instruction folder developed by Dr. Svante Oden (Sweden), who is acknowledged as the ‘inventor’ of the ninhydrine process for developing latent prints in 1953. Dr. Oden prepared this folder for Nin-Spray, a patented sprayer for ninhydrine released in 1961. The interesting part of Dr. Oden’s technique was recommending that the application of ninhydine “be supplemented with treatment with water vapour”.

The article illustrates ‘weak’ ninhydrine prints can be improved by exposing the area with the print to steam vapour under controlled observation. It seems as if this steam method will darken weak ninhydrine prints (article has good before and after illustrations). It is acknowledged that this steaming can be risky and the improvement must be closely monitored to prevent damage to the latent print. This steaming seems to improve the latent print by exposing it to higher relative humidity levels of 70/80% at +22 degrees centigrade.

While laboratories have procedures that involve the “curing” of ninhydrine treated evidence in humidity cabinets, it would be interesting if steaming of weak ninhydrine prints ever after humidity cabinet treatment could be recommended as an additional/last resort step for weak prints.

Something from the past that may be of value.

[Tazman]

Hi Ernie

I think I must be missing something here. How is this different from spraying, dipping, or painting with a nin solution, letting the paper dry, then using a steam iron held an inch or so above the paper? We've been doing that for decades. I learned it at the FBI in early training. I presume they got it from the original source you name.

Or is this something different?

[Ernie Hamm]

Well, I am sure this qualifies as a senior moment (and I do have them) as I failed to recall the ol' trusty steam iron!!! I was getting caught up in the article's illustration of a column of steam from a boiling water flask (not sure they had steam irons back then). Have to brush out those cobwebs, but it was such an interesting account of what was then a relatively new and developing processing method.

Oh well, back to the tar pit. Thanks for the memories!!!

[Graham F]

Ah, the joy of the steam iron!!

I think that most of us would agree that the addition of increased humidity to the process of Ninhydrin latent development is a plus. It accelerates the development process and as Ernie mentioned it has the ability on occasion to darken weak Nin prints and “must be closely monitored.” For “monitored” I feel this means “controlled.” Too much of the, “Dashing Away With The Smoothing Iron” as the old song goes and you may lose the print you are trying to enhance.

Yes a steam iron will work, but what is the control? Is it the wool setting, or the linen setting, or any other setting you wish to choose? The latent community has often under sold itself, I and others I have spoken to believe. How many examiners make do with a steam iron as their only tool, or an uncontrolled fish tank for CA (CNA) development? We just make do with the short end of the stick. No funds for the nice controlled environmental chamber, has for some continued to block the path of a better development tool. Would the equivalent cost of a chamber have thwarted DNA progress, or some other forensic discipline? But, alas in the latent arena, it has at times, been the norm.

Luckily for me I have always had the opportunity if utilizing the benefit of the controlled environment since the mid 80’s. Thank you, Met Police London and the Forensic Science Service (so sad about your demise). Controlled chambers virtually large enough to stand in, that undertook both NIN & DFO type processing were available. Separate chambers were not required for different Nin & DFO humidity control. Don’t listen to the sales hype of the suppliers for individual systems seems to ring in my ears. Prior to then it was the iron for small cases, or the added heat of the photographic roller without humidity. Albeit, this was great for bulk processing, but leave the exhibit for 7 days for latent development. That said, in extremely serious cases i.e., multiple homicide IED events in areas of the middle east in 2005 we are forced backwards to the uncontrolled wool & linen steam iron from the PX. Does it work - yes? Is it ideal - no? How many insurgent murderers did we not identify through inadequate controlled development? Alas, we will never know.

The question will always remain that a steam iron may well work quickly to aid the development of latents, but how many do we lose by uncontrolled processing methods. Maybe a study & paper are called for. However, the result may well be swayed in PD’s & Bureaux to the lower cost iron option by Administrators over the improved method of a chamber under control, producing robust & repeatable processing. With the never ending issue of minimal budgets for many latent departments, the question may always remain, did we fail to develop the prints of the culprit with the steam iron and could we have improved on the final result with more suitable equipment & methods. Great stuff fort the defense attorney. Ah, the never ending story.

[Tazman]

Hello Graham

In the US, most latent print operations are performed by civilian personnel in police departments. That means we compete with the "real police" for scarce resources. In two city police agencies where I worked a few decades ago, I bought much of my own equipment. My fingerprint camera was a Crown Graphic that I found in the newspaper classified ads for $100 and, when I graduated up from a $5.00 fish aquarium, my superglue cabinet was a plywood box with a light bulb for a heating element. And, of course, I used an old steam iron of my wife's to develop ninhydrin prints (yes, I bought her a new one). I figured as long as the department bought all the fingerprint powder and tape I needed, I was well off.

When I changed employment to a real crime lab with more reliable funding, they got me a Mason Vactron 5000. I cannot imagine the response if I had asked a small town police department for $50,000 to buy a superglue cabinet!

I think the new emphasis on "good science" has made funding for most fingerprint units better than it used to be. But I suspect many in the US still suffer from having to make do with the cheapest ways to get things done.