Re: developing latents on carbon paper
Posted: Tue Apr 19, 2011 2:05 pm
I was wondering if the substrate in question was ‘carbon’ paper or perhaps NCR (no carbon required) paper like you encounter with receipts and such. I had no information on processing techniques for either paper.
However, on visible marks seen on the ‘carbon side’ of NCR paper, there may be other considerations. Pressure on the non-carbon side to the paper when a hard surface is against the carbon side can produce visible marks on the carbon side, but the marks’ features will be in a positive orientation to those in the object responsible for the mark. This has been seen in several cases involving footwear tracks found on paper receipts walked on during an incident, such as a robbery when credit card receipts have been tossed on the floor. This is similar to the same type of phenomenon seen in back-transfer of tread patterns to the inside of clothing upon impact of footwear or tire.
Is it possible that a latent (patent) friction ridge print could be a back transfer when encountered on NCR paper or even carbon sheet paper? There have reported instances in which a latent print has been developed on a surface touched by a person wearing latex gloves. If there is sufficient pressure and quality of friction ridge structure, which seems to be the case with latex glove transfers, it would seem a possibility.
If visible latents are observed on such items as carbon and NCR paper, it could be prudent to compare them in positive and negative position.
However, on visible marks seen on the ‘carbon side’ of NCR paper, there may be other considerations. Pressure on the non-carbon side to the paper when a hard surface is against the carbon side can produce visible marks on the carbon side, but the marks’ features will be in a positive orientation to those in the object responsible for the mark. This has been seen in several cases involving footwear tracks found on paper receipts walked on during an incident, such as a robbery when credit card receipts have been tossed on the floor. This is similar to the same type of phenomenon seen in back-transfer of tread patterns to the inside of clothing upon impact of footwear or tire.
Is it possible that a latent (patent) friction ridge print could be a back transfer when encountered on NCR paper or even carbon sheet paper? There have reported instances in which a latent print has been developed on a surface touched by a person wearing latex gloves. If there is sufficient pressure and quality of friction ridge structure, which seems to be the case with latex glove transfers, it would seem a possibility.
If visible latents are observed on such items as carbon and NCR paper, it could be prudent to compare them in positive and negative position.