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Help With Math


thesoapbox

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I am not very good at figuring percentages. I am more of a ml, tsp, cup type of person lol!

So, I am wanting some help from all you math guru's in figuring out preservative amount.

Here is the recipe:

3lbs 4oz sea salt

3 cups oil

4 tbsp butter

In ml's, how much of Germall Plus would I add to this type of recipe?

Thanks so much for any help!!

Angi

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Angi - you cannot mix and match units in a formula/recipe (well obviously you CAN but it's not right and leaves huge room for error). You will need to get the weight of each portion then calculate the amount of preservative based on that weight by the % recommended.

although you are a volume person, the formulas are typically based on weight.

you could kinda estimate volume if you assume each component is the same density of water - but you could be off significantly.

OR you could figure out the weight of the preservative needed, weigh that out once to check the volume or if you know the density do a quick calculation to get you volume and THEN do volume after that.

But its much easier, IMO, and more accurate, to stick with weights - so there is no confusion.

ETA: I myself have trouble with time, as I prefer to work in light years... ;)

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Angi - you cannot mix and match units in a formula/recipe (well obviously you CAN but it's not right and leaves huge room for error). You will need to get the weight of each portion then calculate the amount of preservative based on that weight by the % recommended.

So what would the equation look like? weight x percent?

Angi

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One more dumb question.

Am I preserving the entire concotion or just the oils and butter parts?

ANgi

What usually needs preservatives is anything with water in it, because that's where the nasties grow. Your recipe has absolutely no oil, but I presume it's a scrub, which people tend to use in the shower. There's a high chance water may get introduced into the jar. Since your product is anhydrous, you're not so much preserving your product as making sure it stays nasties-free if this happens :)

With just any recipe, you'd be preserving the whole concoction, not just certain parts.

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The recipe does have oil, scroll up, it is 3 cups lol. The supplier I got the preservative from says it is compatible with all cosmetic ingredients and good for water based items not only for water based items. I used it mainly because water would definitely be introduced into it. When I questioned them they said it was fine in a scrub /shrug.

Angi

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The recipe does have oil, scroll up, it is 3 cups lol. The supplier I got the preservative from says it is compatible with all cosmetic ingredients and good for water based items not only for water based items. I used it mainly because water would definitely be introduced into it. When I questioned them they said it was fine in a scrub /shrug.

Angi

Oops! That was a typo, I meant your recipe has absolutely no water, not no oil, sorry. Liquid germall plus will work in an emulsified scrub (and other water-based and o/w (oil in water) and w/o (water in oil) products), but it won't mix properly into an anhydrous one.

Here, these are good reading, might help some :)

http://www.fromnaturewithlove.com/library/preservatives.asp

http://www.soapdishforum.com/forum/lofiversion/index.php/t38891.html

http://www.lotioncrafter.com/store/Liquid-Germall-Plus-pr-16169.html

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