MP and CP weight difference?

[MuddleDesigns]

I've always wondered this, and could never find a straight answer from my google searches.

Melt and pour, and cold process soaps, are made from roughly the same materials. But molds always say something like "Three pounds of melt and pour, and two pounds of cold process."

I understand the difference between weight and volume, but if both MP and CP are made in weight measurements, and are made of the same oils, why is there such a big difference between the two when it comes to molds? If this has been answered before, then I suck at google.

 

[DeeAnna]

You've provided part of the answer: "...made from roughly the same materials...." You're also assuming the two types of soap contains these ingredients in exactly the same proportions, which is not correct. Also M&P contains large amounts of solvents such as sugar, glycol, etc. that regular soap does not.

 

[ItsForrest]

As I understand and interpret there are a few variables.

As DeeAnna stated, M&P and CP are not really made using the same materials.

More often than not, CP recipes call the recipe size by the weight of just the oils, not the weight of the whole recipe. A 2 lb recipe uses 2 lbs of oils PLUS water, lye, as well as any fragrances and/or other additives. So a 2 lb CP recipe actually has more like 3 lbs of stuff in it.

With M&P, the finished weight of the product is the same as the recipe weight.
With CP (or HP) some of the recipe evaporates in the curing process. After curing for 6 or 8 weeks, a recipe that started with a total of 48 oz of ingredients may only weigh about 40 oz.

 

[cmzaha]

Here are a couple of links to a m&p base, not all ingredients are the same. I will mention these are very nice m&p bases.
Propylene Glycol, Sorbitol, Deionized Water, Glycerin, Sodium Stearate, Sodium Myristate, Sodium Laureth Sulfate, TEA-Lauryl Sulfate, Sodium Chloride, BHT

Glycerin, Sodium Cocoate, TEA-Lauryl Sulfate, Sodium Stearate, Propylene Glycol, Cocamidopropyl Betaine, Sorbitol, Sodium Laureth Sulfate, Deionized Water, Acetamide MEA, Butyrospermum Parkii (Shea) Butter, BHT, Sodium Metabisulfite, Titanium Dioxide

 

[DeeAnna]

"...CP recipes call the recipe size by the weight of just the oils..."

Good point, Carolyn. I'd not thought of that.