Carbon Printing Problem

I had been using ADOX paper as my final support but recently switched to fixed out Ilford matte paper.

I was able to make some good carbon prints – without any frilling but now I have experienced a weird issue
hot
Even after a 15 minuted hot 115F development, some of the pigment will not release off of the image. I have to keep adding water over the print to get some of the pigment off BUT not all of it will release.

Any idea as to why this could be happening? I am using the same pigmented Yupo as to when I had good results and have not changed my process..

Thanks for any thoughts you might have,

Not enough info. Could be caused by a number of things including:

overexposure -- do a base exposure test to determine the minimum exposure required to achieve maximum black, then follow up by printing a step wedge
to ensure you are getting a full range of tones

spontaneous hardening of the tissue (dark effect) -- make sure your tissue is viable be printing; if using isopropyl, ensure there are no funky additives (same goes for
pigments)

very thick tissue -- consider using thinner tissue if you are currently pouring to a wet height or more than about 1.75mm

tissue substrate is waterproof (Yupo, mylar, ...) -- may require some adjustments, or consider using a different substrate

Hi Philip

I know this problem is hard to figure out. I have been printing several images and only recently encountered this problem. I have not changed my procedure or chemicals.

Not that hard to figure out Start by reviewing your workflow, then run some tests changing only one variable at a time. I would start by testing the solubility of your tissue: develop a small piece of unsensitized tissue; the gelatin should melt completely, leaving a clean substrate, in about 10-15 minutes. Next, verify your base exposure. Then pick one representative negative for you subsequent testing. This is especially important if you are using in-camera negatives. Including a step tablet with each of your test prints can be very helpful.