Have any of you had this problem. I applied a layer of hydrocal to smooth out the subterrain a bit under the track. I did it Wednesday morning about midnight. By 7pm that night it still wasent dry. In fact parts were fluffy, kind of foamy. There were some good size cracks forming too. I took a small piece of basswood and packed it down. then made a thin mix of the hydrocal and used a wet foam brush to apply and smooth it out. I added some stain to water and foam brushed the color on all the white hydrocal. I left the A/C on low incase the humidity had caused these cracks. Its too soon to check but this is the first I’ve had this problem. Does anyone know what caused it? I’d like to prevent it from happening again. Thanks.
You infer in your post there, bionicworm1, that you are not a novice in the use of Hydrocal. I’ve never encountered the problems you outline but - and this is only a wildassguess - it sounds suspiciously like your plaster may have gotten contaminated with humidity. I have, upon occasions, thrown unused plaster away because my gruel just didn’t feel right when I was mixing it or when my paper towels were soaking in it - I could have precluded troubles by doing that - this may be Arizona but we can, and do, get some humid weather occasionally.
There is a very BIG possibility that you are right about the bad batch. It has been very very wet and humid here in New York the last couple of weeks. I havent worked on the layout due to lack of AC in that room. When I mixed the first batch I opened a new carton but added some from an open one. It may have been bad. I never thought of it before. I checked at 2am Thursday and it was drying ok with the AC on (just incase). It’s still humid here. Thanks.
I also feel that your plaster has been compomised, other factors are very hard water(high mineral content) or extreme dry conditions affecting curing time. I doubt these are the case in your instance. My club buys hydrocal in bulk. It is repackaged into smaller lots in plastic food storage baggies. and then stored in a sealable 5 gal pail. The moisture problems here in Ma. is about same as you experience. The small bags are great for handling and occasional mold making and scenery work. Plaster has stayed fresh for years this way.
Try adding some white glue to your mix? I have done this with plaster, hydrocal, and Durham’s water putty. In all cases, you get some added strength. No guarantee it will work for your case, but you may be no worse off for the try? Good luck.
I’ve had the same problem with several brands of plaster, almost always after a long string of thunderstorms lasting several days. Sometimes it’s not too bad and I can still use it. Other times, I have to throw it out and open a new bag.
I would just like to thank all of you who replied. I feel that the hydrocal must have gone bad from the humidity. After I let it dry a day (24 hours) with the AC on I only had a few hairline cracks left. I mixed another batch tonight (Thursday - Midnight) wet the area first and added the new mixture where I needed it. It mixed, applied and dried much more like I expected it should. In fact this batch was with the stain added! Everything went great and the track was back up and being tested by 2am… Again thanks to all of you, it may be a simple thing but when it’s just not working quite like it should it’s nice to know this forum (and it’s helpful hobbyists are here). I’m just about ready for building my custom bridges and applying ballast, then wireing for DCC. Since the AC is in the window i’m on a roll!