how do i get castings out of woodland scenic s molds? i have tried the soap and water they suggest but they still continue to break. Any suggestions would be great. Thanks. i am following the instructions to the letter.
Are you waiting too long before removing them? Using the hydrocal, maybe 10 minutes after it gets hard, I remove from the mold.
Michael
CEO- Mile-HI-RailroadPrototype: D&RGW Moffat Line 1989
The mold says remove after 30min and i tried it and the rock split in half so i waited an hour on the next one and it turned out a little better , i am trying to cast facet rock the mold is pretty big also it,s about an inch or so in depth.
Mine come out just fine. The only time I ever broke one taking it out I had mixed the Hydrocal wrong. Even after removing it it was very brittle. You can use toothpicks or small sticks like re-bar if you are making big rocks.
For a mold release agent I use wet water. I pour it in the mold, slosh it around so the entire mold is wet, pour it out, and pour in the Hydrocal.
Dave
Lackawanna Route of the Phoebe Snow
Are you using Hydrocal? Are you coloring the plaster? I believe that whatever plaster you're using is old or has been compromised by absorbing moisure. Once Hydrocal hardens you can rip the rubber mold before breaking the casting. Excessive coloring additives, not formulated for plaster/ masonry such as paint etc, can compromise the final cured casting. I am still using/ reusing molds that have made 100s of castings. Also check that the mold is clean, usually even w/ some bits left, you will only have minor details break off and remain in the mold.
Modeling B&O- Chessie Bob K. www.ssmrc.org
I'm not a "rock mold guy," so I don't use molds unless I'm working on a layout where the owner prefers them to hand-carved. With that caveat as to my somewhat limited experience, I have used the WS brand molds a few times, and found them to be fairly stiff as such things go. Compared to some of the other molds, they do require a bit more care to ensure the casting isn't broken. One trick to keep the casting in one piece even if it breaks is to embed some cheesecloth into the plaster after pouring it into the mold, so the fibers act like rebar to hold everything together.
Since you state you've used the soap and water mold release to no effect, maybe trying another release agent would work. I've used cooking spray like PAM with OK results, and it didn't seem to affect the ability of the plaster to accept stains.
Rob Spangler
I use Plaster of Paris(the Hobby Lobby tubs) and have never had any breakage issue with the W/S molds(and I have 'all' of them). I think you have 'old' plaster.
I like to use Plaster of Paris as it takes my rock stains better than Hydrocal. I do use Hydrocal for the 'shell' of the base scenery and 'paint' 120 minute patching plaster over it as I blend in the rocks.
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
I bought a big jar of Hydrocal a few years back, and used it slowly. When I got down near the bottom, I found that my Hydrocal castings were very brittle. I bought new Hydrocal, and things were fine again. So, it appears to me that Hydrocal has a shelf life on the order of a few years, even if you keep it in a sealed jar as I did, opening it only to take a bit out for a casting.
It takes an iron man to play with a toy iron horse.
Thanks I think you guy's are right, I must have old Hydrocal . I just tried one with plaster of Paris and it worked grand, i have a bunch of it left over from another project and might as well use it up. Is there any way to tell if the Hydrocal is old? Or should i just keep using the plaster?
bear's lair Is there any way to tell if the Hydrocal is old? Or should i just keep using the plaster?
Is there any way to tell if the Hydrocal is old? Or should i just keep using the plaster?
It's hard to tell if Hydrocal is old unless you witness how it behaves as you use it. It sounds like yours is indeed old. Starting with my own personal biases, I don't think the Hydrocal brand is of much importance for most model scenery applications, regardless of the decades of hype surrounding it. If the Plaster of Paris works for you, go ahead and keep using it. If for some reason you find the plaster unsatisfactory, find some newer Hydrocal.
Storage of any plaster product is very important. My club will buy the 99# bagged Hydrocal (found @ commercial building suppliers). Even an unopened bag will absorb moisture rendering the plaster ineffective for casting. We will "repack" plaster into baggies (approximate size for most individual projects) and store in a sealable 5 gal container. This allows the plaster to remain fresh for years, if it lasts that long. Also makes for easy and less messy use.
Another point: for coloring, I have found that using powdered masonry dyes far superior to any of the Sacrete liquid or paint additives. The color is easier to calculate- adding dry to dry will give the color of the mixed, cured final product. Once any coloring agent added to wet you can only approximate what the end result will be, and duplicating additional color batches is near impossible. (Think of tile grout, dry initial color is same as finished
I have used them with no problems, at time some of the rock edges broke off, but that was no big deal. I have used plaster of paris and hydocoal with no issues. Just be careful removing the molds as I had a mold get a small tare in it. Good Luck
I have used these molds successfully, using wet water as a mold release agent. I let them set up about 45 minutes before popping them out.
There is also another way you can get crumbly plaster: too much water. As some have said, it does absorb moisture from the air. You can also mix too much water with it, or leave too much of the mold release water in the mold.
That said, for big rock faces, I much prefer using Sculptamold carved with a palette knife.
Connecticut Valley Railroad A Branch of the New York, New Haven, and Hartford
"If you think you can do a thing or think you can't do a thing, you're right." -- Henry Ford
I have had the same problem and solved it by removing the casting 10-15 minutes after I poured it, prior to a full cure, as mentioned earlier.
FYI: The wet water (water/liquid detergent) is not used as a release agent but to break the surface tension and allow the Hydrocal to penetrate all the details of the mold.
John