Keep the volume of the embedding molds small (such as using small gelatin capsules), mix a small volume of accelerator into the LR White; add this to the gelatin capsules with samples already in them (in a small volume of LR White to prevent drying), cap the gelatin capsules, and then put the samples into a freezer.

I've done the above procedure a number of times; the small volumes and cold temperature allow polymerization without excess temperature buildup in the sample. If the sample was too hot, the gelatin tends to warp/melt a bit so you get immediate feedback regarding polymerization temperature.

I would also heat polymerize a few blocks; 24 hours at 50 degrees C. You may find that your antigens of interest survive this temperature and so the above procedure

may not be necessary.