beaker design

Discussion in 'B&W: Film, Paper, Chemistry' started by Poco, Jan 24, 2004.

  1. Poco

    Poco Member

    Messages:
    653
    Joined:
    Sep 7, 2002
    Shooter:
    Multi Format
    A few months ago I bought some Bomax beakers from Photographer's Formulary and, believe it or not, I'm not sure I'm using them right (!). The problem is that the last measuring mark on each beaker is one level shy of its rated capacity: the 1000 ml is only marked to 900ml, the 50ml is only marked to 40ml, etc... There's plenty of extra glass (capacity) available for that last critical mark, but the damned things just aren't there. Obviously, it's not difficult to guess where they would be, but I'm wondering whether the design assumes some procedure used by chemistry-literate people that automatically results in the proper measurement. Stupid as I am, I just can't figure out what that would be.
     
  2. Silverpixels5

    Silverpixels5 Member

    Messages:
    594
    Joined:
    Mar 19, 2003
    Location:
    Houston, TX
    Shooter:
    Multi Format
    The 1000mL of the beaker is just the maximum capacity, and so they never show the graduated marks up to that amount. Even the marks on there are only nominal and not precise. If you want accurate amounts then I reccomend a graduated cylinder. If a close ballpark is what you are after then just get a beaker or flask that is larger than you need so that it will have the marks up to where you will be using it.
     
  3. Poco

    Poco Member

    Messages:
    653
    Joined:
    Sep 7, 2002
    Shooter:
    Multi Format
    Thanks, Silver. I still find it strange that a beaker, advertised as 1000 ml and having more than enough capacity for that amount, doesn't bother showing you where the critical level actually is. I've got a scale rated for 1000 grams that doesn't peter out at 900.

    Okay, rant mode off. I just wanted to make sure I wasn't overlooking anything obvious.

    Thanks.
     
  4. Ole

    Ole Moderator Staff Member Moderator

    Messages:
    9,281
    Joined:
    Sep 9, 2002
    Location:
    Bergen, Norw
    Shooter:
    Large Format
    Poco, it's just the same with all beakers. They're not intended for measuring, just mixing and heating. The markings could easily be made more precise, but then I guess somebody would complain that they're not precise...
    A graduated cylinder is generally used for measuring - you can easily calibrate (put a line at the approximately right place) your beakers to use them for mixing photo chemistry. We don't need 3 decimals precision, after all.
     
  5. Poco

    Poco Member

    Messages:
    653
    Joined:
    Sep 7, 2002
    Shooter:
    Multi Format
    Ole,

    Yeah, I've come to the conclusion they do it to discourage people from using them to mix chemicals -- measurements are imprecise and we'll make damned sure you know it!

    Doesn't stop me, though :smile: