RTV Silicon

[Fomen38]

Larry, I saw one one of the lure making episodes of Hunt For Big Fish that you poured molten lead into a RTV silicon mold. I was just curious what is the quantity of lead you can pour into a RTV silicon mold, and how many pours can you get out of the mold before it's trashed from the extreme heat? I'm thinking I will be pouring anywhere from 12-14oz of lead in a single shot. However, I obviously want to mold to last as long as possible. Do you think this will work? Thank you for your time.

Scott

[dahlberg]

I've never used rtv for anything quite that large. Largest around eight ounces. I use the putty and get many dozens if not hundreds of pours depending on the shape and how much bending and stretching of the mold is needed to remove the part. I would say give it a try for sure if you can make an open cavity mold one piece mold. Otherwise, like I said depends on the shape. If you decide to do it, make at least an inch wall thickness.
best
L

[Fomen38]

Larry- Please forgive my ignorance as I have never used the mold putty before. What you are saying is that I can make a 1 piece mold using the mold putty (as opposed to the RTV silicon), and this mold will withstand the blistering temperatures of the molten lead? Thanks again for your time and expertise.

[dahlberg]

THe putty has a different base which is more heat resistant. It's also a great deal stiffer which is great for lead. If you make a one piece mold and it's open on top, it cools more quickly and the part slips out with very little effort. It won't last for ever, but it will work pretty well and I'm sure more than pay for itself.
best
L

[Fomen38]

Larry, I know this topic was posted up a loooooong time ago, but I had a question once again regarding the mold putty. Alumilite offers up 3 varieties of mold putty. Which type is best for casting lead? Thanks in advance for the reply.

Scott

[dahlberg]

Any of them will work fine. I've been using the "15" formula because it allows more working time and is a little softer while molding, so it's easier to fill voids and cracks. After forming, I'm sticking it in a preheated oven at 250 degrees and it's setting up in ten minutes or fifteen minutes.
good luck!
L