Is caulk a good substitute for RTV?

[MillenniumFalsehood]

Okay, here's the scenario: I am going to make a few different chocolates for Valentine's day in the shape of various Star Wars ships and characters(droids). I was going to use plaster of paris to make the molds, but they wouldn't be flexible enough to release the chocolates(or the toy masters). Would regular old caulk be good enough for now since I'm only using it for making candy molds? It should be non-toxic, as it's used in bathrooms and kitchens all the time.

[USS Atlantis]

Okay, here's the scenario: I am going to make a few different chocolates for Valentine's day in the shape of various Star Wars ships and characters(droids). I was going to use plaster of paris to make the molds, but they wouldn't be flexible enough to release the chocolates(or the toy masters). Would regular old caulk be good enough for now since I'm only using it for making candy molds?

Well, even at it's hardest, standard silicone caulk is VERY flexible.

It should be non-toxic, as it's used in bathrooms and kitchens all the time.

There's a difference between touch non-toxic and contact-with-food non-toxic - the carriers in bath/kitchen silicone caulk can 'leak' for a while, and never really go away - that's what keeps it flexible.

Contact with food - I'd much rather hand-shape the pieces than use caulk-molds to shape chocolate - and even if I did use the caulk-molds - I'd only give the chocolates to someone I really didn't like

I'd also stay away from most of the modeling RTV's and get hold of some 'food grade' RTV - yes, they have them - but Smooth-On (my prefered RTV supplier) doesn't list any

Atlantis

[Chacal]

I believe tile caulk has some anti-fungal chemical or other to make it less susceptible to mildew (at least some around here have it). Another potential problem is that there are many silicone caulks which work with acetic cure, meaning they output a strong vinegary smell as they cure (and for quite some time).

I have seen chocolate molds done in common vacuformed acetate (very common here in Brazil, and cheap to boot. The problem is that this kind of mold doesn't accept undercuts, but you can mold two halves apart and then 'cement' them with a dab of molten chocolate. You can even do a two-part hollow mold of something bigger, like the Death Star (just like they make chocolate Easter eggs) and fill it up with little Star Destroyers and Tie Fighters.

[Joseph Osborn]

I've seen some stuff at Michael's or Hobby Lobby called "Amazing Mold Putty" that is supposed to be safe for casting food items. I've never used it myself but maybe it's worth looking at if you have a crafts store nearby.

link:
http://www.craftsetc.com/store/item.asp ... 0&Search=Y

[MillenniumFalsehood]

That Death Star idea sounds pretty cool! I think I'll try that, pending the purchase of the food RTV. $15 isn't too bad either, and I can see loads of uses for it. The Star Destroyers I'm molding are one-piece toys from the old Star Wars battleship game, so I need something which can handle undercuts; vacuform molds won't work here.

So regular old caulk could be used for a mold for plastics and resin, but not for food, right?

[TER-OR]

I've seen some stuff at Michael's or Hobby Lobby called "Amazing Mold Putty" that is supposed to be safe for casting food items. I've never used it myself but maybe it's worth looking at if you have a crafts store nearby.

link:
http://www.craftsetc.com/store/item.asp ... 0&Search=Y

I've used Knead-a-Mold, and it's OK.
Don't expect perfection, but it's not bad.

[USS Atlantis]

So regular old caulk could be used for a mold for plastics and resin, but not for food, right?

Definitely not for food - and I don't know what the Acetic Acid in caulk would do to resin, and that leeches out for a few days.

Atlantis

[eeun]

If you can get hold of some in time, dental alginate would be safe to use...though depending on the brand it might leave the chocolate with an extra minty taste.
That is, as long as you're casting something that's flat one side, with no undercuts.