CLPEX Chat Board

Note: For Atmospheric NOT vacuum

Hi,
We are having a discussion in our lab about how long items should "set" after fuming before dye stain is applied. We have all come from other labs and half of us applied the dye stain around the time it was finished fuming (using an automated chamber there is a 20 minute purge for it to "set") and the other half wait 12 hours before applying the stain. We are currently rewriting our policy to require a minimum of 12 hours, with any deviation from that requiring a good reason. Being in the camp that prefers to dye stain earlier, this seems to be overkill. I am just wondering what the majority of labs are doing. If you have a minute, please throw in a vote. Also, if you are in the 12 hour camp do you have a research paper that shows the benefit of waiting 12 hours?
Thanks,
PG

The purge cycle on the CA chambers that I was using was only 5 minutes, and I generally also waited a "few" minutes after the purge cycle of the CA chamber to apply the dye stain, typically a half hour at the longest.

Why would you specify in a written policy how long you have to wait to apply a dye stain? What standard are you interpreting as requiring you to define a waiting time between CA fuming and dye stain application?

Not sure why we are specifying in a written policy how long we have to wait

I don't think there is any standard requiring us to define a waiting time, it is more that this is a practice they were used to at previous labs and would like it applied here. There is apparently some literature on it (CBDIAI recommends it "sit overnight" and that looks like it is from the Secret Service), but I have yet to see a research paper on it. I have heard of and experienced lower adhesion with vacuum processed CA items, but have never run into issues with ATM CA.

As I am in training, I use our CA chamber pretty often (practicing on mock evidence), and I'll do it whenever I'm ready after the purge (our machine has a 10 min purge cycle). As long as my QC test print doesn't smear, I'll dye stain as soon as I am ready. I have not noticed any difference between those and when I will run the chamber before I leave for the night and come back the next morning for dye staining.
-LEC

Once the chamber has purged, I process my test print before evidence. That give an additional 30s to 60s of 'drying' time before I hit the evidence with dye stain. I have never lost a print as of yet. I am also in the camp of early and not later which seems unnecessary and not based on research. For those that want to wait 12 hrs, I would ask them why other than it was how I was trained.

I've seen research where one group recommends upping the temp of the chamber and introducing humidity to improve development of CA fumes. I have also read research that suggests cooling the chamber to reach optimal development. One day drinking coffee kills you and the other day one or two cups a day is good for you.

Same thing for nin prints; I can spray a piece of paper with nin, let it dry and place it in a ziptop bag overnight or for several days hoping to see development or I can hit it with hot steam from an iron and get results immediately. Just seems to make more sense to process it quicker than later IMHO.

While I don't specifically wait before applying dye stain, sometimes there is a lot of time in between CA and stain. If there are latents visible with just the CA, I'll photo those first. I've just seen too many prints that looked better after CA but before stain.

In any case, my vote for 0-30 minutes is in cases where there are no photos to take and I still have time left in the day to spray on the stain.

I would agree with some of the other replies, especially if a test print is being run. Personally, I haven't seen any documented research calling for an extended wait time before CA and a dye stain. You could probably do a small in house study to explore these time differentials, or if you performed a validation to look at those parameters, but in my experience it isn't required. Like ER mentioned, often I will have a lapse between techniques due to photography of CA developed latents, but often over the course of my career thus far, once the purge cycle has completed and a visual exam done post-CA, your dye stain could be used.

Would this be a case of writing your policy and procedure documents far more detailed and restrictive that ISO requires, so that in the future you find yourself handcuffed and blame ISO for not allowing you the discretion you might need?

It is definitely writing the policy more detailed than ISO requires, which could cause headaches down the line. There is a qualifier that allows for a deviation if it is a rush case, but that is it. I don't think we would blame ISO for it (unless this is decades from now when everyone here has retired and there are new people running things that don't know the background).

Outside of now having to wait till the next day to dye stain (which will slow things down), I am concerned that once it becomes Policy it will be VERY difficult to remove. We have experienced that in the past with our Quality Manager.

I have talked to about 10 people that wanted to vote and comment but for some reason couldn't log on or even create a new account. They ended up telling me that they were in the 0-30 range and they felt (universally) that 12 hours was unnecessary and exessive. My feeling about this is that slowing down the processing backlog for something that a only a few people have experienced is misguided. There are no scientific studies that I could find that supported waiting 12 hours and on the contrary I had been told by one person that the prints had been processed and held for over 12 hours and the print "melted." Thankfully and correctly they photographed it first. So we don't know if its the type of CAE, the matrix, the substrate, the time we stain, handling or a mix of these that causes this to happen. Rarely, I will add. Why would you slow down getting investigators good leads and sacrafice 99 percent of cases for that one percent or less of cases that may have an issue with this? Especially when you are photographing first.

SuperInnappropriate wrote:I have talked to about 10 people that wanted to vote and comment but for some reason couldn't log on or even create a new account.

I see that five people tried to create a new account yesterday (Wednesday). Did they get the email to confirm their registration? I just resent it to the email they used to sign up.

If someone has a problem logging in, they can email me at:
seeverist
at
yahoo.com

I will need the username they are registered with and then I can create a temporary password for them to log in.

Just replace your CA bottles with Lumicyano, a la the old Folgers commercials and watch the fun ensue...

We are actually going to be validating Lumicyano for use in casework in the near future, but it will probably not completely replace using a dye stain (at least in the near future).

Just one idea to think about on the policy exception for a rush case - if you are putting in your procedures that you'll wait 12 hours before dye staining, presumably that is because someone thinks it gets better results and is a best practice. So why would it be OK to dye stain sooner in a rush case, which I'm assuming would be a more serious crime where you're trying to catch a violent offender for example? By that logic, a more serious case gets a "substandard" processing procedure because you're applying the dye stain sooner than you really "should". Not sure if anyone else sees it that way, but that was my thought reading through the thread.

Also, I've never seen a huge difference applying the stain immediately after SG versus waiting an extended time (due to photography as mentioned above). I'll be interested to hear what your lab ends up going with for the policy.