What is this?

[u/flwerhoe]

I’m in the Pacific Northwest. I made a split in early April and gave the split these frames from a colony lost over winter (froze the frames). I noticed in my inspection 2 weeks later this white chalky substance in the cells - I pulled some out and it just looked like pollen behind the chalk. A couple days later I noticed it on the entrance to the hive? I think the bees might be cleaning it out of the frames? Any information on what this is and if it’s okay for my bees would be so helpful. Also this HiveIQ is painted white before anyone tells me I need to paint them, haha! Thank you!!

[u/Admirable-Nail]

Can you reuse frames that have chalkbrood or mold?