Re: Dichromate dilution and speed

Sandy King wrote:
>
> Katharine Thayer wrote:
>

>
> Now, if there is a relationship between Baume and percent solution,
> and you can tell me what that relationship is, then you will have
> answered my question. I could then calculate the final gum percent
> solution of your coating and compare it to Sam's coating, and/or to
> the percentage of colloid in my carbon tissues.
>

There are many people who don't have a hydrometer and mix their own
powder at 30%, whether in the belief that 30% yields 14 degree Baume, or
the knowledge that 30% works fine, I I can't say. Whether their success
at doing this shows that that relationship is true, or whether it means
there's more latitude in the specific gravity requirements for gum
printing than is generally understood, I can't say. I've always assumed
that the relationship is not 100% reliable, and that's why the specific
gravity is specified rather than the percent solution. The feeling that
the relationship is inexact is one reason I've always let someone else
mix my gum and verify that it's 14 degree Baume, since I don't have a
hydrometer.

But I think the exactitude you demand is beyond what's reasonable for
gum. It's like insisting that numbers be given to the 5th decimal place
when there simply isn't that much precision in the measurement.
Katharine
Received on Mon Dec 1 11:29:39 2003