fluid ounces vs weight ounces

[dggriffi]

I'm trying to calculate the amount of oil to use in order to fill my hand made mold to an appropriate level. I have calculated that i need 128 fluid ounces of end product. Applying the .40 modifer i believe that i need to start with 51.2 fluid ounces of base oil.

SO

i can melt my oils and measure them and then weigh them for get the ounces for lye calculation

OR

if i can find the various densities(or weights) of the various oils to do the calculations up front without melting, measuring, weighing, and then adding to the crock.

Any thoughts.

fyi, i have found that coconut oil has a density of .92

 

[IanT]

do everything by weights, not by fluids, its waaaay less complicated and you will find that most of the recipes that people give are all by weight, or percentage of oils (and also if someone says that you need x amount of oils for a mold, it usually means its in weight ounces, not fl oz)

 

[cleanwater]

I think you may be overthinking it (or I am underthinking it, I've only had one cup of coffee his morning :? ). There is a sticky by Soapmakerman on this subject. If your mold is a regular shape, it's really easy:

(Volume of mold in cubic inches) x 0.4 = (total weight of oil in ounces)

If you're aiming to fill to an exact point in your mold, you may want to make extra soap batter, fill your mold to the right point and put the rest into a small "leftovers" mold.

Hope this helps

 

[theBrewMeister]

you'll find that, especially when using the metric system, that they about the same. 250ml weighs 250g of water. Oils, with respect to their specific gravities are really close as well. If you didnt have a super acurate scale then you wouldnt even notice the difference.

I like using the metric system because all my equipment, beakers, flasks, scales, are metric. Also, once you use it twice for making soap you'll find that your life is soooo much easier! Converting back and forth between grams and kilos is alot easier than converting from ounces to lbs and visa versa.

think about it like this. If youre making a 1000g batch, which by-the-way is 1 kilo or 2.2 lbs (a nice test batch size, for me anyway), your percentages are alot easier to figure out. 90% = 900g. Im American but I wish we'd convert over.

1lb = 453.59 grams
1oz = 28.35 grams
1kg = 2.2lbs

 

[Tabitha]

the problem is different fluids have different wieghts so their is no difinative answer.

Think about a pound of feathers & a pound of bricks. They will not be the same volumn.

 

[dggriffi]

I think you may be overthinking it (or I am underthinking it, I've only had one cup of coffee his morning :? ). There is a sticky by Soapmakerman on this subject. If your mold is a regular shape, it's really easy:

(Volume of mold in cubic inches) x 0.4 = (total weight of oil in ounces)

If you're aiming to fill to an exact point in your mold, you may want to make extra soap batter, fill your mold to the right point and put the rest into a small "leftovers" mold.

Hope this helps

I sure hope im over-thinking it. Essentially, my mold is of unusual shape which is whats driving this whole affair. I obtained the volume now im making the slide into weights.

 

[dggriffi]

the problem is different fluids have different weights so their is no difinative answer.

Think about a pound of feathers & a pound of bricks. They will not be the same volumn.

thats actually the point of my post. I needed to get the various weights per ounce. Turns out coconut's density is .92 and palm kernel is .886 which is what can be used to derive weight.

 

[carebear]

the 0.4 conversion factor is very approximate anyway. it depends on the strength of your lye solution and everything. make up a batch which you know is bigger than you need, weigh the mold before filling and after you fill it to exactly where you want it and then back calculate to cut your formula down by a %. the math is relatively simple and more accurate than playing with all those individual specific gravities (which are all rounded off, and all those errors are additive).

 

[Tabitha]

I always make a bit more than I think I will need, soap, lotions, whatever. Then make sure I have a couple small molds or sample size containers & the excess goes in those for freebies or samples. It's easdier than math plus you ge the little extras to play with or give away.

 

[carebear]

I also like my little "extras" because I usually let me log molds gel, but the individual "extras" don't - so I always have a reminder of what it could look like in case I want to try it without gelling. another reason I save them is so I know what the stability of the FO is like.

and as freebies for drop-ins. always have those!

 

[dggriffi]

all good advice and i hope i have some extra left when its done for those very reasons. Without any experience to guide me, i had to start somewhere. So i figured my volume, cut to 40%, split the quantity in half for coconut/palm kernel, calculated weights on these fluids based on density and used a calculator to get my lye amount aiming for 8% fat.


I guess we shall see how it goes.