CLPEX Chat Board

Hello, does anybody have any experiences/opinions on or about the physical developer kits from Arrowhead Forensics that are sold in a powder form? Anybody have any issues with the maleic acid pre-wash seeming to weaken certain papers? Anybody have any issues with the development strength of the physical developer itself? Anybody have any experience with reducing the amount of the powders in equal ratios to make smaller batches?

Our lab is currently comparing the powder based kits to the pre-mixed liquid kits from Sirchie with the hope that the powder based kits (with their longer shelf life) can be kept on hand and used as needed.

My agency has used the premeasured kits from Arrowhead and Armor Forensics (now Forensics Source). Actually, the maleic acid prewash is the only component that comes in powder form in these kits, to be mixed with distilled water for a working solution.
The physical developer solution (part A) and silver nitrate (part B) come premixed as a stock solution to be combined into a working solution just prior to use.
The shelf life of the stock solutions are shown to be up to one year, but I have noticed that they start losing effectivness after about six months. I have only noticed the degradation of some types of paper that are not good quality with the maleic acid prewash.
We now order chemicals and mix our own stock and working solutions as we need them for this and other chemical processing techniques. The shelf life on the stock chemicals pays for itself over the pre mixed kits in the long run, and you can mix up only what you need in proportion to the job at hand. We have just in the last year went from ordering premixed chemicals to mixing our own. We use the "Processing Guide for Developing Latent Prints" obtained from the FBI for our processes and "recipes" along with those obtained from other training and shared information from other departments. We also always do controls on any solution used in chemical processing prior to use on any actual evidence, to "proof" the solution. Hope this helps.

Thanks Mark for your reply. I'm thinking that the all powder kits are relatively new to Arrowhead Forensics but we've ordered them and have them on hand. Our ordering person thinks that they're part number A2622 and run about $55.

We also use the liquid stock solution kits that you referenced. We were comparing the liquid stock solution kits to the powder kits that we bought since the powder kits have a longer shelf life.

ok, I learned something new today then! thanks and sorry for being behind on the information you were looking for