The Importance of Being Accurate?

[MrsSpaceship]

It's just my husband and myself, and I've already sent soap home with our friends/co-workers, because my usual batch gives me 5-7+ bars, and that adds up fast.
I want to try some smaller finished batches (4 - 3oz-ish bars at most) to test different oils, additives, colorants and scents (and use less of my ingredients in doing so). I've read some of the other threads dealing with small batches, and would like a bit more clarification.
The common recommendation is not to get below 1 lb, and I assume they're talking finished batch size. My current scale will measure in whole grams as the lowest unit, so if I keep to my current methods of rounding up to the whole on the oils and down on the lye, am I okay?
Up to this point I've been making 1lb. (oil weight) batches so have felt comfortable doing this.

Take this for example. This is for 9 oz of oils, default water %, and a 5% superfat, the original in black and my numbers in red.
Water: 96.96 97
Lye - NaOH: 36.32 36
Oils: 255.15 256
Fragrance: 7.97 8
Soap weight before CP cure or HP cook: 396.39 397

If I'm calculating it right that's less than a 6% total SF so I should be ok... Am I right or off my rocker?
(I hope this makes sense, maths makes Mrs. Spaceship's brain hurts:crazy

 

[The Efficacious Gentleman]

I make test batches of shave soap that are 50g - that gets fiddly! My measure goes to 0.1g so it is not too bad, though. I think rounding up the oils and down the lye for a normal bar soap is the best bet (for shaving soaps the added sf can cause some issues) and of course being as spot on as you can. When I'm making a big batch of soap I often go over the target slightly but just roll with it as we are talking lower %. But in your example, if you go over on the oils by 5g then you have almost 2% more oil than you were aiming for.

As for the above - I don't know what oils are in your mix to know if the superfat is 6% or not!

 

[IrishLass]

I sometimes make very small batches of 3 soaps for testing purposes, and when I do, I use my scale that's able to weigh accurately down to .01 gram (a Jenning's brand that I bought from Lotioncrafter's). I personally wouldn't attempt my smaller batches without it, especially since the smaller you go batch-wise, the exponentially greater the potential for problems if your lye weight is off by even as little as a titch. It's also great for making really small batches of lotion and lip balm.


IrishLass

 

[cmzaha]

I make as small as 4 oz test bars without stressing. My KD-8000 scale only goes as low as 1 gram and that is what I use. I am not a high superfatter and have yet to have a zappy bar when making a small test batch. I do have a small gram scale that will measure .01 but do not worry about using it for soap. I only sell 1 size and hate having oddball sizes around due to testing.

 

[MrsSpaceship]

Efficacious Gentleman,
my oils was my total requiremet at a 5% superfat (on soapcalc) so when I calculated the difference, I came up with a ".something" difference (it was late, that's my excuse and I'm sticking to it.)
I know exactly what you mean on SF shave soap...I have 7 bars of a lovely tallow blend that I unthinkingly bumped up to a 10% SF. It is beautifully conditioning but won't give a decent lather worth a darn. it's a great hand soap though!

Irish Lass,
I think I'm resigned to having to purchase a new scale. I plan on attempting lotions and other potions in the future so may as well just bite the bullet now even though at the moment I'd much rather spend the $ on additives. C'est la vie, eh?

Cmzaha,
Thank you, I think I'll try it.
I was looking at the KD scales because so many soapers seem to swear by them, but was frustrated when i realized they have the same limitations of the $20 scale I already have.