Does Hydrocal go bad?


meanjean

meanjean

Member
Bought some lightweight hydrocal about 2 years ago. Never used it till now. Mixed it up as per directions, poured into the rock mold. Directions say remove from mold 30-40 min later. I waited 2 hrs and its still very soft, so soft if I try and remove it from the mold it just crumbles apart.

It seems like there is no glue in the mix or something to make it firm up?

Anyone else experience this problem?

oh and I also watched this:

http://woodlandscenics.woodlandscenics.com/show/video/MakeARock

I did it just like he did, no way my rocks can come out after 45 min!
 
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Chad, I use Patching Plaster that I get at my local Ace Hdw. If I don't seal it up completely, like a jar w/a rubber seal it goes bad w/in 2 to 4 months. Same for Hydrocal.
Temperature changes & damp area's will effect it in the container it comes in. Most Hydrocal comes in a plastic or waxed coated container like a 1 gal. milk container & you can also get it in 20 & 30# bags. I've found if you aren't going to use it right away put it in the house where the temp. stays moderate at all times. When it goes bad it won't dry, chalks up if it does dry or falls off the screen that you've spent so much time making a mountain out of. Sometimes it will disendragrate(sp) as soon as you think it's dry. Someone else might have a better solution than mine since almost everyone on this forum uses this stuff in some form or another.
 
You hit the nail on the head. 4 hours later its still damp. Pulled some decent chunks from the mold and put in the oven at 275 deg. Its now dry but falls apart when touched, crumbles to powder if you touch it.
Plaster you say? Does that take a long time to dry? What other material can be poured into a mold and not take weeks to dry?
I hate waiting for stuff to dry.
That may be my new signature phrase?!!!
 
Yeah it will go bad over time, like said, moisture due to temp etc.
I use Durabond plaster compound, it's available in different set times and is available at most home stores that sell Sheet Rock, not real big bags but reasonable price.
 
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Hi Chad,
I purchased a large bag of Hydracal, 90-100lbs about 30 years back and divided it with my buddy.
I've kept my portion stored in a plastic paint bucket with a snap-seal lid and I used some of it to make my stacked stone interlocking rock castings from and everything work great. The stuff I bought was a much faster setting material than what WS is showing though as it seems my stuff dries in about 20 minutes depending on the humidity and air temp.

It could be that your mixture is too thin to begin with, it should like a somewhat creamy mixture. Or that possibly you need to mix the container contents more thourghly and I would suggest holding the carton horizontally and tipping it one way and rolling it a quarter turn and tipping it back the other way and again rolling in a quarter turn and continueing doing that for a minute or more to ensure it is evenly mixed.

Of course it could be WS got a bad batch of the stuff too?
Judging from what I have that was purchased from a track side warehouse in Fresno it shouldn't go bad if kept in a sealed container inside.

I have to use a bit of mine to touch-up a couple of spots in the stacked stone castings as what I used had a number of air bubble pock marks to it so I'll see how it work and maybe even pour a mold or two to test out.

I'll let you know.
 
I did a 2nd batch last night with the same results. I ensured the hydrocal was throughly shaken, the mix was the proper ratio of water to mix and throughly mixed.
Same results.
Ill chuck the container, it has to be bad. Ill look for some plaster or drywall compound.
 
Say Chad,
I'd return it or at least call WS to let them know as I'm sure they'd make an adjustment for you. They were always good to deal with when I called.

Casting plaster maybe alright but most plasters will crack when drying out and drydwall compound is probably no different especially in greater thicknesses unless you've heard differently?
 
The Patching Plaster I use to make mountains, roads & other items takes about 2 or 3 days to dry so you can walk on it. Sheetrock Mud is not a good item to use for molds. It takes forever to dry when it's thicker than 1/8th inch & even at a thin layer it cracks real easy. I use it to make concrete or asphalt crossings over the rails & fill-ins after I make a mountain. It's also good for narrow concrete roads because the cracks look good after you paint it. I think I've tried just about everything that was ever made for Model railroads, home improvement, crafts & school projects in the 50 years that I have been building layouts.
 
Yeah, you can't use regular joint compound for any type of thickness.
That's why I use Durabond, it's easy to find and cheaper than Hydrocal.
 
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