Let me preface by saying that I know the difference between the two options below is practically insignificant in this example, but if the numbers were changed, it could matter, and I'm an overthinking engineer who wants to know the actual intent.

I have some Weed-B-Gon. The directions say, "1 fl oz (2 Tbs)/gal of water/200 sq ft."

Is it:

1) 1 fl oz of the product plus 128 oz of water, making 129 oz of the mixture
2) 1 fl oz of the product plus 127 oz of water, making 128 oz of the mixture

I interpret the answer to be #1, but the OCD is kicking in and I made a spreadsheet. One of my inputs is the application rate. Is it a gallon of mixture per 200 sq ft or 129 oz per 200 sq ft?

its 1 oz PER 1-gallon of water.

Stop over-thinking it and check your meds!

Now I'm wondering how homogenous your application is per sq foot across a 200 sq ft area. And how you're actually ensuring it.

I've always interpreted that to mean, add solution to be diluted, then fill the container to the 1 gallon mark. I see the difference, but it's pretty dang small.

quote:

Originally posted by stoic-one:
I've always interpreted that to mean, add solution to be diluted, then fill the container to the 1 gallon mark. I see the difference, but it's pretty dang small.

See, there's merit to my question. You're choosing option #2.

I'd say the first answer unless this is a trick question.
Maybe it depends, are you or you friend, an ME or PE?

quote:

Originally posted by 220-9er:
I'd say the first answer unless this is a trick question.
Maybe it depends, are you or you friend, an ME or PE?

If a chemist, you'd be referring to molarity vs molality.

You actually measure this stuff?

3. Pour 1/8 of the bottle by hand into the sprayer of Weed b gone, then add water until the bubbles breach the top, let sit, add more water up to the point you can put in the pump handle without it flowing over, then spray weeds

Err on the side of stronger...damn weeds can be tough!

quote:

Originally posted by 6guns:
Err on the side of stronger...damn weeds can be tough!

Again, in this example, it's insignificant, but in principle, I don't want to kill the grass.

quote:

Originally posted by HRK:
You actually measure this stuff?

Of course. You should see the precision I measure for cooking recipes.

quote:

Originally posted by 220-9er:
are you or you friend, an ME or PE?

I'm a PE/SE.

You can't always add liquid measures because the liquids may be soluble in each other. Yes, 1 gal. of water + 1 gal. of water will equal two gallons, but 1 gal. of water + 1 gal. of alcohol will yield something less than two gallons. So, unless the spreadsheet is compensating for the various solubility of the chemicals in WeedBGone, with water, it will be incorrect.

From a practical perspective, the amount of chemical as a fraction of the amount of water makes the issue immaterial. The effectiveness of the mixture for its intended purpose does not require a high level of accuracy in the dilution. There will be far more uncalculable variability in the application rate per plant or per square foot due to operator variance, water pressure variance, nozzle irregularities, and probably a number of other factors. Getting it "close enough" will work just as well as hitting the exact dilution number.

Of course, engineers want to be certain. So, just as designing a bridge that will bear twice the anticipated load is sound engineering practice, going a little strong on the herbicide mix isn't likely to hinder the intended effect.

3) You're wasting your time thinking that hard about it.

Just add the specified amount to a gallon of water, then get a surveying team out to quantify 200 square feet, gridding out each square foot with string line. THEN measure out individual doses of 0.645 fluid ounces per square foot and apply.

quote:

Originally posted by 6guns:
Err on the side of stronger...damn weeds can be tough!

And this is the biggest mistake and waste of product that everyone seems to get wrong.

More isn’t better or stronger.

I was taught and use example #1.

quote:

Originally posted by Keystoner:

quote:

Originally posted by HRK:
You actually measure this stuff?

Of course. You should see the precision I measure for cooking recipes.

Next thing we know is that you read the instructions and layout the parts in sequence when assembling anything, forshame, LOL

If it's critical, it is usually "X part(s):Y part(s)"

Or, 1:127 (ounces for a gallon solution)

When doing lawn, I would do full gallon and add the solute.

If I were mixing chemicals for photpprocess, I would use exact ratios or exact specifications as printed.

The yard can't care due to myriad possible variances one will encounter that makes precision insignificant. So, one ounce to a gallon, either way won't matter at all.

But film and print process is critical for consistent repeatability and quality control. +- 1 degree can affect contrast and latitude of shadow to highlights in the film process, and color shift in color film process.

-Heisenbergmonkey

TMK, the standard for dilutions is X:Y, where the final volume desired is X+Y.

IOW, 1 oz per gallon, is put one ounce in the bottom, and fill to the 1 gal mark.

OCD away.

https://ohioline.osu.edu/factsheet/fabe-530#

quote:

Originally posted by Keystoner:

quote:

Originally posted by 6guns:
Err on the side of stronger...damn weeds can be tough!

Again, in this example, it's insignificant, but in principle, I don't want to kill the grass.

You won't.

I use at least 1/4-1/2 cup (4-8Tbs) per gallon (just eyeballing it) and use it for spot treatment on dandelions, thistles, and other undesirables. No harm whatsoever to the lawn and they're dead in a day or two.

If two tablespoons is good, four (or eight) is better.