The CHP is fairly stable. Therefore, it is possible to reuse a dilute solution that has been heated already, although the intensity of the stain may decrease and results may not be as optimal. To reuse the dilute solution, it needs to be heated to 80C and cooled down again immediately prior to reuse.

The CHP doesn't bin based on a specific epitope, but rather the structural recognition of the individual alpha chains that make up the triple-helix. Because of this, they can bind anywhere along the collagen chain, bind all types of collagen regardless of species or tissue type. You can use the suggested mAb and the CHPs together. 

One thing to note is that usually, mAbs require heat-mediated antigen retrieval, which causes severe damage to the collagen resulting in denaturing all the collagen in the sample. Therefore, the CHP will give the total collagen content in the slide as opposed to identifying any damage caused by a disease or trauma. We recommend either using serial sections where one section is heated for mAb staining and the other left unheated for CHP staining. If you want both on a single slide, we recommend doing an enzymatic epitope retrieval method if possible. 

Finally, it is important to understand that the mAb they wish to use will give them intact collagen content while CHP gives denatured collagen content, therefore the regions will be inverse. 

CHPs form hydrogen bonds with gelatin/Gelma because they have the Gly-X-Y structural motif just like the underlying structure of Gelma. Assuming that you are fixing Gelma with photocrosslinking, most of the methacrylation of gelatin to make Gelma is on the lysine groups, leaving plenty of Gly-X-Y sites for CHP binding.