jigmaster Posted February 11, 2007 Report Share Posted February 11, 2007 Hey, all I want to fill in part of a cavity on a mold for pouring lead....dont want it to be permanant, so JB weld is not an option is there a silicone formula out there that will room temp vulcanize, and once it sets up, I will be able to remove the silicone "plug" when I dont want to use it? and......will that particular silicone withstand lead temps for repeated pours? thanks in advance, oh wise ones regards JM www.daimonlures.com Quote Link to comment Share on other sites More sharing options...
reeves Posted February 12, 2007 Report Share Posted February 12, 2007 JM, there is an RTV that I have just been using to make a master with. The thing is I don't think it will stick to the metal mold surface as it releases real well from the master part after being vulcanized. I did pour two halves to the master, expecting that it would not attach to already vulcanized silicone. WRONG! It vulcanized itself to the cured stuff with no problem, had to cut the master out. If you think it might work for what you are doing give me a PM and I'll be glad to get you the particulars on the stuff. It cost about $25 for a pint. Quote Link to comment Share on other sites More sharing options...
Lotic Joe Posted February 12, 2007 Report Share Posted February 12, 2007 I have used plumber's putty to temporarily block the weedguard slots or to let me pour weedless jigs with a single wire strand in molds designed for bristle guards. You won't be able to remove and reuse the same plug, but it is a quick/easy way to pour a few jigs ......... Quote Link to comment Share on other sites More sharing options...
Mr B Posted February 14, 2007 Report Share Posted February 14, 2007 Try Durams (sp) watter putty. Similar to plaster. It can be chipped away later if needed. If you use any type of water putty make sure it dries for a couple of days. You dont want any watrer in there when the lead is poured in. Mr B Quote Link to comment Share on other sites More sharing options...
jigmeister Posted February 17, 2007 Report Share Posted February 17, 2007 Go to any autoparts store and get the Red colored hi-temp RTV sealant . It has a continueous temperature rating of around 600 degrees and will be easy to clean out of the mold cavity when you're done. Quote Link to comment Share on other sites More sharing options...
Long Lake Lures Posted January 28, 2009 Report Share Posted January 28, 2009 I came across this old thread while researching a problem that I have encountered. I am trying to modify a Do-it mold so that i can make flats on a jig head. I applied high temp silicone to the mold and let it cure for a couple of days. I pre-heated the mold on the pot prior to pouring and poured 6 heads. Each time, there were voids where the silicone created the flat. I was hoping that the voids would decrease with every pour, but they appear fairly consistent. Has anyone experienced this and have you found a solution? Thanks, Dave Quote Link to comment Share on other sites More sharing options...
jigmeister Posted January 29, 2009 Report Share Posted January 29, 2009 I am not quite following what part of the jighead you're blocking off with the silicone (is it the head itself or the skirt collar?) . The red hi-temp silicone is supposed to withstand around 500 deg continuous I believe . Does the silicone look like it is burning at all? Another substance that works when modifying molds is "JB weld" . I have blocked off the skirt collar on round jigheads with the JB weld to make shakey heads and it works fine . Quote Link to comment Share on other sites More sharing options...
Long Lake Lures Posted January 29, 2009 Report Share Posted January 29, 2009 Jigmeister, Thanks for your help. I am trying to copy the design of some of the football jigs where there is a flat surface cast into the jig head so that the trailer will stand up when the jig rests on the flat. I didn't see any signs of the silicone degrading after six pours, but the voids persisted. I am thinking that the silicone is acting as an insulator, creating a cool spot which solidifies the lead prematurely. I am working in an unheated detached garage, so the ambient temperature is COLD:eek:. I was hoping that someone else has already gone down this path and can provide direction. Also, does hi temp silicone and JB hold up to the temperature over time? Thanks, Dave Quote Link to comment Share on other sites More sharing options...
Vodkaman Posted January 29, 2009 Report Share Posted January 29, 2009 Correct, silicon is an insulator. But this would create a hot spot, not a cool spot. But I doubt this is affecting the result. What do the 'voids look like? Are the voids in the exact same location each time? A close up pic of the mold and the cast might help. I suspect a tiny amount of air is trapped behind the silicon patch. This being due to the shiny surface of the mold when applying the patch (poor adhesion). When pouring, the air expands, causing a spherical (bubble) void. The bubble is too small to break surface tension. Try tapping the mold immediately after pouring, to shift the bubble. This does not come from first hand knowledge, just applying engineering. Dave Quote Link to comment Share on other sites More sharing options...
