Casting problems

"Don Stauffer in Minneapolis" wrote

- Make sure you are mixing properly. Some are by weight, some by volume. I've also experimented by mixing 10-20cc samples of proportions varying slightly to either side of what's recommended to calibrate a good mix with the measuring devices at hand.

- When you get a good mix pour talcum powder into the molds first, slosh it around and shake out the loose stuff, then blow out the molds. This aids filling small details incredibly.

KL

Both temperature and humidity affect setting time. However, it sounds like your problem is in the ratio of catalyst to resin. You might try varying the ratio by adding a little more catalyst to the resin at about 60:40 and see what happens. If you're still having problems, up the ratio a little more. It might not hurt to mix just a small amout and pour it into a small disposable plastic cup (like the ones that McDonalds catsup and hot mustard come in) to make sure the ratio is correct. Also, make sure to mix the two parts completely as, incomplete mixing will also affect the way it sets up.

Hope this helps and good luck with the project.

-- -- -- -- -- "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm." George Orwell

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I've never tried the talcum powder trick before, Kurt. I'll have th give that one a try; thanks for the tip.

-- -- -- -- -- "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm." George Orwell

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"Bill Woodier" wrote

I was amazed at the results myself. And, just blow (with your mouth) lightly to remove lumps - you want to leave a dusting over everything.

KL

Sometimes you have to mix what's in bottle A with itself then what's in bottle B with itself before attempting to mix the two parts together.

The trick for me is finding real talcum powder, unscented as that "baby fresh" stench gags me.

"Ron" wrote

Corn starch works too. Buy the white J&J bottle, not the pink or blue.

KL

Thanx for the tip !

I dont or ever have made a mould that big tho...

"AM" wrote

The dusting idea is mold-size independent. The smaller the detail being replicated, the better it is.

KL

That indeed seems to have been the problem. After several of you mentioned this, I tried a test mix last night. I had only been rocking the bottles once. The instructions said rock bottle several times, so I really rocked them a number of times. I didn't mix enough to cast the tires, but the mix seems to have set up in a few minutes like it is supposed to, in the cup, and looks fine. I still need to clean the old resin out of mold, and will do a new pour today.