Dryness indicator sources - small quantities

Discussion in 'Investment casting Ceramic shell method' started by Chassy, May 4, 2023.

  1. Chassy

    Chassy Copper

    Hi, does anyone have a source for small amounts of a dryness indicator like Remet or ReDip? Everything I've seen is in large, expensive quantities.

    I'm kinda wondering if there's some type of indicator available from chemistry supply companies, though I don't have the background to know what would work and be safe. For example, there are these, and I wouldn't be surprised if one was the active ingredient in Remet or ReDip: https://www.riccachemical.com/products/chemical-indicators/dry-indicators

    I'm actually doing dip coats on lost foam, but I've only seen this stuff in the context of making ceramic shells. I want to be able to go from dip to pour as quickly as possible, thus my desire for an indicator to know as soon as the piece is ready. Normally, I just let it hang and dry for a few days, but I'm hoping to be able to do everything in a day.

  2. ddmckee54

    ddmckee54 Silver

    Would a moisture meter like what's used to measure moisture in lumber work? Most of them use pins that have to be jammed into the wood, which might not be a GOOD idea for a ceramic shell, but there are pin-less varieties of the meter too - of course THEY cost more.

    I see that Horrible Fright has one for $14, probably of the pin variety. Maybe try that one as an experiment on shells you don't care about to see if it works, then get a better one if it works? They list the accuracy as +/-2% for wood and +/-0.1% for other materials. You might have to experiment a little to determine what % moisture that YOU think is "ready".

    Chassy and Tops like this.
  3. Chassy

    Chassy Copper

    Interesting idea!
  4. Can't you use the old chemistry set humidity indicator using cobalt chloride: it's blue when dry and pink when it contains some moisture: paint a solution on some paper squares and let it dry.
    Chassy likes this.
  5. Chassy

    Chassy Copper

    Hm, I see those strips for sale on Amazon. I could try just sticking one to the dip coat and watching for the color change, although I'm a little wary of what the heat may decompose cobalt chloride into something nasty, though probably at a very low volume.

Share This Page