Measurement Question

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BrewerGeorge

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Just had an odd thought while thinking about my peppermint-lavender-cedar question. How do you all account drops as volume with EO's?

It occurred to me that I'd automatically been using the old rule of thumb from school that 10 drops = 1ml, but is that valid? That RoT is based on water or at least on aqueous substances with particular physical characteristics. But EO are oils with different viscosity, surface tension and density than water.

Does everyone just ignore these differences as noise, or what?
 

dixiedragon

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I am one of those naughty people who measure my fragrance in volume. I think it's close enough. If I were doing something truly miniscule, then it might be a problem.
 

LilyJo

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I was reading something yesterday on this in a perfume making book...

So, just found it again and it says "if you dont have scales......as a guide 25-30 drops of essential oil = 1g. However, it doesnt hold true for all oils for example patchouli is heavier than lemon so 1g patchouli is not the same as 1g of lemon (it has fewer drops)..."

In essence (!) they say that 25-30 drops of EO is ROUGHLY 1ml not the 10 drops to 1ml you mention, not entirely sure which is correct but the 25=1ml is what I use.

Dont know if that is any help or not!
 
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Sorry, I weigh my fragrances now. I used to use volume, but one batch would be scented almost too heavily, then the next would be too light. And this was when I was using nothing but EOs.
 

Soapmaker145

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Just had an odd thought while thinking about my peppermint-lavender-cedar question. How do you all account drops as volume with EO's?

It occurred to me that I'd automatically been using the old rule of thumb from school that 10 drops = 1ml, but is that valid? That RoT is based on water or at least on aqueous substances with particular physical characteristics. But EO are oils with different viscosity, surface tension and density than water.

Does everyone just ignore these differences as noise, or what?

On average, 1 drop is about 50 microliters. You need 20 drops to get to 1 ml. I measured it with a micropipeter, testing multiple EO bottles with droppers. At least the ones I have seem to be consistent.
 

DeeAnna

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"...You need 20 drops to get to 1 ml...."

I agree that that this particular rule of thumb is often used, but the more detailed references I've found don't necessarily agree with this estimate. See attached.

"... It is commonly thought that there are 20 drops per milliliter, and this is true of water when using 'standard' measuring tools... However, the number of drops per milliliter of a liquid is not only affected by the dropper, but by the properties of the liquid itself. There is a property called "cohesion", which causes the liquid to stick together more or less. Water has high cohesion, therefore the drop sizes are larger and there's fewer drops per milliliter. The high cohesion requires that the drop weigh more before it separates from the rest of the liquid. Each essential oil has a different number of drops per milliliter!..."

Average 42 drops / mL
Max 52 drops / mL
Min 25 drops / mL

Source: http://www.anandaapothecary.com/measuring-essential-oils.html

View attachment EO drops per mL.pdf
 
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