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spgreene
16-Oct-2006, 23:03
Mixed HC110 into a Solution A mixture but need Solution B and can't figure out the math to further dilute. Solution A is made from a 1 part stock to a 3 part water=Solution A but Solution B is 1 part stock to 7 parts water=Solution B. Any mathematicians out there??? Thanks

Eric James
16-Oct-2006, 23:24
Just add 4 more parts of water.

1 part stock to 3 parts water is a 25% solution.

1 part stock to 7 parts water is a 12.5% solution.

Double the volume (add 4 parts) and you half the concentration (25 to 12.5%).

Cheers:)

spgreene
17-Oct-2006, 00:30
Many thanks......

Donald Qualls
19-Oct-2006, 13:50
You have Dilution A and need Dilution B -- A is 1+15, B is 1+31, from syrup. Simple, then -- use equal parts Dilution A and water, and you have dilution B. Multiply by 16 to see how it works -- add 16 parts A to 16 parts water, and you have 1 part syrup and 31 parts water, total. High school algebra texts say you can do this kind of "concentration" problem as either water + water = water or solute + solute = solute -- I find it easier to just look at it as fractions (but then, I learned to add fractions in second grade, by watching the fourth graders learn it on the other side of the room).

spgreene
19-Oct-2006, 21:47
Good God!!! No wonder I feel so stupid.....and being a high school dropout certainly didn't help. Many thanks...

Donald Qualls
20-Oct-2006, 16:40
No need to feel stupid -- lots of high school grads can't do fractions in their heads (probably most of them, come to that). Even I can't, if they're ugly ones, but I've worked with the ones related to timekeeping (12ths) and the ones related to measurements (12th, 16th, 32d, 64th, etc.) so much over the past 30 years that I almost don't have to think about them -- and many times find it easier to work with the fraction than the decimal equivalent, even if I'll be converting to decimal (for instance, in order to check the result with a dial caliper or set a cut depth on my lathe) in the end.

The real funny thing is, I dropped first semester calculus twice (to avoid flunking) before finally getting through it -- I'm living proof that arithmetic, however complicated, is not at all the same as mathematics.

Michael Graves
21-Oct-2006, 07:39
Good God!!! No wonder I feel so stupid.....and being a high school dropout certainly didn't help. Many thanks...

Don't feel too badly. The first time I used HC-110, I read the directions too quickly. I missed the part about making a stock solution from the concentrate. The directions said to mix stock 1:9. So I mixed the concentrate 1:9, grumbling the whole time about how expensive this stuff was going to be at this rate. For some reason the negatives came out extremely dense and contrasty. Didn't like the developer at all. Now when I use it, I dilute the concentrate 1:64 and develop twice as long as the recommendation for 1:31. I like the results a lot better.