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.

    Thanks!
     
  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".

    Don
     
    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.
     

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