[mblanco2000]

I have asked this question before about mixing chemicals by weight instead of by volume.  We have a small blending facility, and are currently trying to come up with a new chemical.  First I need to do some small test batches to see if we like the new finished product.

I have scales so I can weigh all my chemicals.  These are the chemicals I will be blending together and their weights per lbs./gallon. and the percentage I want by weight in the blend design.

Water 8.35 lbs/gallon             78%
Chemical A 9 lbs/gallon           20%
Chemical B  8.72 lbs/gallon        2%

So do I just pick an arbitrary weight for my finished product and then run percentages off of that to get the amount I would mix in my blend?  Thanks for the help.

[Borek]

If chemicals A & B don't contain water, doing what you plan to do should work.

[mblanco2000]

Chemicals A and B do not contain water.  So would it be easiest to just say I want to make a test batch that has a finished weight of 4.5, that is roughly the average of all the chemicals lbs./gallon divided by two.  I would assume this would give you about a 1/2 gallon of finished product.

Water 8.35 lbs/gallon             78%
Chemical A 9 lbs/gallon           20%
Chemical B  8.72 lbs/gallon        2%

My mixing ratios would be:

Water 4.5 * .78 = 3.51 lbs.
Chemical A 4.5 * .20 = .9 lbs.
Chemical B 4.5 * .02 = .09 lbs.

However the above formulas do not take into account my original lbs./per gallon?  I feel like I am on the right path but missing something here.  Thanks for the help guys/girls.

[DrCMS]

However the above formulas do not take into account my original lbs./per gallon?  I feel like I am on the right path but missing something here. 

If you are weighing each material into the blend then their density is irrelevent. 

If rather than weigh the materials in you decide to dose them in by volume then you will need to adjust for the density.

[gluedudeguru]

I have been dealing with the exact same problems as you for over a year now.  I have an incredibly under stocked lab in a company that doesnt even know what i do.

I think that what you are doing when worying about the #/gal is worrying about volume.  If you just take the 4.5 # and set that as a final weight, the only thing the #/gal number will do is indicate how close to a half a gallon is (could calculate volume prior to mixing).  Seeing as though you just want percetages (wt/wt) just taking the compisition # and multiplying it by the overall weight will give you what it appears you are looking for.

In other words, your previous post's math was correct for wt/wt calculations.

FYI, I hate measuring liquids in weight, but I have to do it too.

[mblanco2000]

As scary as this may sound I am the owner of this very small chemical company.  We bought it about 5 years ago and we had some existing products that have done pretty well.  Now we are trying to expand our chemical product line.  Here is the scary part, until our budget gets a bit bigger I am the chemical developer.

I actually enjoy it, but I am starting out at ground zero.  I ordered chemistry for dummies the other day from amazon.  I would like to find some real world text that might help me in blending different liquids together, or I can just bounce stuff off you guys from time to time.

[Borek]

Water 4.5 * .78 = 3.51 lbs.
Chemical A 4.5 * .20 = .9 lbs.
Chemical B 4.5 * .02 = .09 lbs.

That's correct. It would be easier to measure by volume, to calculate volumes you will need to use mass and density. But there is nothing wrong with weighting liquids, it is just a matter of convenience.