Sunday, August 26, 2012

Question: How to weigh feather light things?

In this post, Julie asks: Speaking of difficulty weighing things, I'd love for you to cover this....Feather-light ingredients. I can't figure out how to weigh my Silk Peptide. I don't see how it could be by weight since it is so light. At 3% in a recipe I needed 5 grams of it. When I weighed it on my scale it filled an entire ounce measuring cup, which didn't seem right to me. I contacted the supplier to ask about it, and they weren't really sure how to weigh it. They just told me 5 grams would be equivalent to .18oz. So I ended up using 1 teaspoon (.18oz x 6 tsp in an ounce = 1.08tsp) since that seemed much more like 3% in a 6oz recipe. I'd love to hear your thoughts on how to weigh ingredients like Silk Peptide that are super light. I can't think of any others off the top of my head, but I'm sure there are plenty of others. Thanks!

I have that trouble with Natrabath - the stuff weighs so little, and I end up with a quarter cup for 10 grams or so! - but I weigh it like my other ingredients. If you have trouble measuring things, put your jug on the scale and count up from that number. For instance, if I put my 2 cup Pyrex jug on the scale, it'll be about 670 grams. Start there. If I want 5 grams, I'd just count to 675 grams and be done with it! I rarely start at 0 when I have small amounts to weigh.

Water is 1:1 - 1 ml of water weighs 1 gram - this is called its specific gravity. If you are using 1 tsp or 5 ml of silk in your product, you're assuming that it has the same volume as it does weight. This is highly unlikely. If you were using sunflower oil, adding 1 ml means you're adding 0.9 grams as the specific gravity of this oil is 0.9. Some things are lower than one, some are higher than one, but very few things are 1:1 for volume and weight.

As an aside, 1.08 ounce is 5 grams, but that doesn't mean that it is 1.08 ounces in volume. This gets confusing for me because we use millilitres and grams, which are clearly different words for different things, whereas Americans use ounces for volume and weight and don't often specify which they are using. Cooking shows can get very annoying very quickly for me! I like the way Alton Brown started saying "by weight" after the word ounces! But then again, I like everything about that man!

Powdered things - especially very light powdered things - can be a pain to measure, but we have to do it by weight or we're not getting what we want in our products. I suggest getting a smaller scale or doing the thing I suggest above, which is to weigh the entire product and add to that number.

Any other suggestions?

11 comments:

Diane said...

I just recently read a suggestion (think it was on this blog) to pick up the container and set it back down on the scale - which seems to work. I have the same trouble with VenaSilk (oat flour, Herbarie.
PS My good friend ruined her Kindle screen by just tossing it in the computer bag without a cover. It can get damaged.

Anonymous said...

Yes, I agree with Diane's information! Pretty much, the issue is that your scale cannot discern the minute difference of 1/4, or 1/2 grams, and therefore it allows you to build up to un-proportional amounts before registering the change (like that study that shows that if some animals get in slightly warm water and it is slowly brought up to a boil over x amount of hours, they wont register the change and invariable boil themselves to death (wow.. sorry for the downer example there :/ )).

Anyhow, it is more laborious, but picking up, and setting it down again does reset the scale and should give an accurate read.
~Neal

Ingrid said...

Hi Susan and Julie,

I have had exactly the same problem with trying to measure silk peptides or silk amino acids into recipes. The scales just don't take an accurate measurement (in my mind, for the ratio I want in my recipe.)
I also just measure a level teaspoon full and be done with it.
Same with Nutrasorb Bath for my bath melts and milk bath - I have calculated this ingredient by measurement, not weight, for my recipe. It turns out perfect so who am I to complain?
Cheers, Ingrid

melian1 said...

i think the question is whether the seemingly large amount for the seemingly tiny weight is correct, rather than how to weigh it (being as it is light).

it can seem like i'm adding waaaay too much of something to get the proper %age - by weight - but having confidence in the supplier's (or vendor's) useage rates, i do it anyway. and so far it has worked out well.

i just had to get over the sight of a huge pile of what i was weighing.

Anonymous said...

Hi Ladies,
I had the same problem mesuring small amounts of powdered and light ingredients. Altough the method described by Susan worked, I finally invested in a good 200g x 0.01g scale AND a weights set for two reasons:

1_ I'm a precision freak...lol
2_ I am still looking for my perfect recipe so I prefer to test small batches.

I mentionned weights because I realised that many people don't know it's paramount to verify their instruments accuracy once in a while.

Have a nice week
Maryse

Julie said...

Hi Susan,

Thanks for helping with this. I know and understand that weight doesn't transfer to volume without doing the math for specific gravity. I did it anyway though because it didn't seem right to me when I weighed it because of the huge amount in comparison to the small percentage. So even though Silk Peptide is used at a small percentage, it actually ends up looking like a lot more than 2 or 3% of Cetyl Alcohol would look, for example? Hmmm, I thought for sure it couldn't be right when I originally weighed it. Better safe than sorry though, I know it's only Silk but if it was something else I could've ended up with a serious problem!

I did buy a scale that weighs to the hundredth recently, so I have no problem actually weighing the ingredients, it was just the huge volume of it that I was asking about.

Two other super light ingredients I've found since asking about it are Salicylic Acid & Green Tea PE (although I'm pretty sure the sample I got of it isn't the kind for cosmetic use since it ruined my lovely first toner I was so excited about making!).

Well, thank you for the answer! Now that I know it's safe to use these ingredients I'll be able to use my Silk Peptide and actually see what it's supposed to do. No wonder I couldn't feel any effect of it in my cream!

Ingrid, how did you calculate it, by specific gravity? And did it equal the same amount as if you weighed it?

Melian1, yes! That is what I was asking. My scale is incredibly (and surprisingly) sensitive, the physical amount of is what I was confused about.

catherine said...

Maryse, I do testing in small batches as well. 10 g or even 100g I count as small.

What I do for powdered ingredients is make liquid concentrates. First check solubility. For example niacinamide is 100% soluble. So I make a niacinamide liquid concentrate of 7g niacinamide, 7g h2o, .14g preservative. I put it in my handy dandy 15ml dropper bottle from brambleberry. Label it (ingredient, concentration, expiration). For oil soluble powders I use fractionated coconut oil. For alcohol soluble powders my new favorite thing is propanediol, a mild ecocert alcohol.

This is great for early stage, small batch formulating. You can always adjust your recipe for larger batches later that use only the dry ingredients.

For this a .01g scale is a necessity. Not too expensive. $15 at bulkactives.com.

Can I add 1 more thing, esp to the newbies? I'm a sorta-newbie too...feb 2012. Before using your 'real' sometimes expensive ingredients, practice measuring using water, cooking oil, etc for liquids and flour/salt for dry ingredients.

I wish i'd done this when i first started. I wasted a lot of ingredients in the beginning because of overpouring/incorrect measuring/etc.

Anonymous said...

This is probably really silly, but I had a hard time measuring out preservative accurately when I was making small (<100 g) test batches. I agree with what Susan said about adding directly to your container. I also think it works out ok to tare my plastic pipette to get a very precise amount. You just have to be very careful to squeeze out every last drop (which sometimes is impossible so maybe not the best method?) For solids, you could try weighing your ingredients on parchment paper or weighing paper and kudos to Maryse for using the weights to be extra precise!

-Alex :)

Bob & Angela said...

If you absolutely have to, you can estimate the weight by volume (although I don't recommend it, and I'd never do this in my lab.)You need a reliable volumetric measurement - say 1 level tablespoon, for example. Weigh 10 or 20 tablespoons (or however many) of ingredient, doing your best to keep each tablespoon-full exactly the same. When you've measured out enough of the ingredient to get an accurate weight, you can do the math to get an average weight per tablespoon.

You can do the same thing to get an average weight per drop from a pipette, too.

TikiBarSoap said...

All Americans don't use those weird measurements :) I use mL and g as well, its what makes sense to me.

Nyssa said...

I wondered about this last (and the first0 time I made something... being a small batch, my preservative was difficult to measure.
Thaks for the tip about picking it up and putting it back down again! I was wondering if maybe I should 'negative measure' - put the whole bottle of preservative on the scales, suck out enough with the pipette until it reads 1g (or 2 or whatever) lighter. Haven't tried it though, it was just a thought. :)