CLPEX Chat Board

Is anyone (with an available ALS) currently using fingerprint powders FIRST, then dyestains such as RAM or Rhodamine after CA. It seems to me that the use of powders and lifting tape would remove some of the polymerization from the CA. I have seen both ways listed in general Chemical practices. Just looking for a consensus.

Sorry not to answer your poll, but I believe this one warrants a more detailed response than clicking a box, particularly since the choice I would pick doesn't exist.

In our procedures manual (and in practice!) it is equally acceptable to either powder first and then RAM, or to RAM first and then powder. It is very rare that we would do only one or the other, although that does also occur in certain instances.

In my personal experience, I have had both positive and negative experiences with both options. In other words, I have processed first with powder, gotten nothing, then had good results with RAM; I have processed first with RAM, gotten nothing, then had good results with powder. On the flipside, I have had fabulous results with RAM, continued onto powder, and gotten a dirty mess with no visible detail and I have also had fabulous results with powder, then gone on to RAM and only managed to wash out the detail I had previously seen.

The short answer (in my opinion!) is that either way is acceptable and can work, but which order to use in a particular case is completely dependant upon the case itself, the substrate, etc. Some items seem to respond better to powder first, and others to dye stain.

Heidi

I too can't really answer the poll because as Heidi indicates I think each case is different depending on the evidence. As a general rule, we find that employing dye stains prior to powder provides better results than powdering first then dye staining. Between the two, in my experience, the latent usually develops better with the dye stain than the powder, but if the dye stain follows the powder, the dye-stained image just isn't as good as if the latent wasn't powdered at all. The powder seems to interfere somewhat with subsequent dye staining, almost masking parts of the fluorescence at times. This is especially true on plastic drug bags/saran wrap. Typically, dye staining prior to powder is a much more fruitful effort and gives better results than the other way around. We usually do follow up the dye stain with powder and occassionally the powdered image will be better, but not often!

Mark Mills

I agree completely with Mark. I meant to put that in my previous post, and forgot -- we typically will use RAM prior to powder. I have observed the same general trends that Mark mentioned when I do it the other way around. However, you do occasionally get that piece of evidence (usually when you can see the print fairly well after CA and powder would simply serve to improve the contrast/allow for lifting, etc) that just screams "powder me first!"

Heidi