Hello everyone,
I have three questions.
(1) do you use mold release on the W.S. rubber rock molds?
(2) if so. What do you use?
(3) lets say your planing on making 3, 4, or maybe less molds. How do you know how much you need to mix, with out mixing to much that would be wasted.
Thanks,
Sam
Sam:
I use “wet water” as a mold release agent most of the times I cast rocks with WS rubber molds. I have from time to time not used a mold release agent with good results also. Some time ago there was a post on how to estimate the amount of plaster needed for a mold but I didn’t note it down since I have already calibrated my molds by trial and error. Try the search function and maybe you can find it or someone else will chime in with the link.
Joe
I heard wet water works, but I used a lub with silicone in it(a must for mold release use).
As for how much plaster, which mold set do you have? I have the outcroppings set, so I used about two cups of plaster and added as much water as I needed. I you have extra left in the cup, RINSE IT OUT BEFORE IT DRIES!!!
I forgot once…
…It did not end well…
… acually it was fine but a pain in the butt to get out.
[:-^]
sfb
1,2 I just spray with silicon, the same type used to treat rubber products and lubricate, etc.
Richard
The problem is you don’t want to have too little, and fill a mold half full and have to quick mix up more…although, I’ve sometimes intentionally done that to make a casting that’s a little different from the standard casting from that mold.
BTW the rubber mixing bowls from Micro-Mark work well. You dump any unused plaster in the garbage (don’t wash it down the drain, it can clog your pipes) then let the bowl dry. When fully dry, bend and flex the rubber bowl and the hard thin plaster breaks up into pieces and can easily be thrown in the garbage. A light was with soap and water make the bowl completely clean.
Wet water, but don’t allow to get too much or too sudsey. The main concern is that after use you clean the mold. This is esspecially true on tyhose intricate casings where small pieces of plaster may be left behind. Scrubbing with a small stiff brush is generally all thats nec. Avoid digging or causing any scratches. I have reused W/S molds may dozens of thimes and they produce the same sesults every time.
As for the amount of plaster to mix, you will get a feel for it as you gain experience. Even though I have been mixing batches of plaster for years, you still will never get it that close. So what I do is have additional molds ready to pour, these can be the ones that will work even if partially filled.
I use wet water also. Always has worked fine.
As for amount to mix. Excess is not really a problem. I take a piece of tin foil, crumple it up, spread it out, turn up a lip around the edges, wet. I pour the mold full and any excess I put on the tin foil, fairly thin. You can use the whole cast piece for a rock face or you can break it up as talus. Use the same washes to color it as you do the rock face it will be at the base of.
Good luck,
Richard
Just curious, doesn’t silicone prevent washes, paints etc from sticking to the plaster?
You took the words right out of my mouth. I too have taken any extra and poured it into a self made foil rock and used it as extra fill or talus. And I just spritz my molds with a little wet water also and have never had any issues with them coming out. Not sure about the silicone trick but I assume it would work fine as you can buy ready made rocks made of silicone rubber that take paint and washes. I use a basketball that I cut in half to mix plaster in…(He ticked me off one day and I popped it…long funny story) It works well when the plaster dries in it as you just squeeze it and any remaining plaster falls out. Also gives the layout room that “sports bar” look…lol…Good luck…Tim
It did not for mine, but be careful not to put too much silicone in, and if you are still worried, try wiping it out, it will still work.
I use wet water. I pour it into the mold, slosh it around and pour it out, then pour the Hydrocal while it’s still wet. I mix the Hydrocal in a flexible container, and when it dries, flex the container and it breaks and falls right out. Throw the dry pieces in the garbage. NEVER DUMP THE LIQUID DOWN ANY KIND OF DRAIN.
As far as quantity, I just line up multiple molds and pour until I run out.
Not had that problem. Of course I don’t flood it either.
Wet water for me, too.
I use yogurt cups to mix my Hydrocal. First, fill the mold with plain water. Dump it into the cup, and mark where it comes too. Dump it out and mix your Hydrocal to the line. Make a little extra, actually, because you won’t be able to get all the mixture out of the cup and into the mold.