Right now, I’m redoing all the cinders in my service area. Area keeps cracking and going goofy. No other area does that. Strange.
Interesting -- I had much the same happen to the cinders I used to border some of the tar paper 'roads' on my layout:
[Please ignore the watchtower in the road -- I'd moved it to that location for a pic, but it's the only closeup I have at hand of the cinders on the road edge]
My current diagnosis is that the watered white glue I sprayed on did not have enough wetting agent (IPA, in this case) to allow the glue mix to fully penetrate the cinders, resulting in a relatively fragile crust forming that will crack and break into chunks on the least provocation. Haven't yet attempted a fix, but my current plan is to break up the clumps, and respray with more watered white glue, with a higher percentage of IPA and perhaps some detergent as well. The problem that's giving me pause is that this is directly over paper-backed grass matting, so too much moisture and the paper backing starts to corrugate! Let us all know if you find a better fix, please . . .