Mixing by weight - calculator

[lemental]

At the moment, I mix by weight but have yet to find a calculator that gives me recipes in grammes.  I just convert ml to g using a standard calculator at the moment.

I saw Perpetua's post here with a recipe for her VC.  Looks like a spreadsheet but I may be wrong but I've checked the figures and it uses the same ml to g ratio for PG, VG and concentrates that I currently use.

allaboute-cigarettes.proboards.com/post/317317/thread

Where can I get my grubby hands on it from?!!

[chykensa]

I'm not quite sure what the advantages are of you mixing by weight. As everything is liquid, surely the best and most efficient way to mix is by mililitres (or even drops if you are working in really small quantities).
Accuracy using syringes can be really quite precise, and at the end of the day, a drop either way won't make a massive difference and mess up a recipe.
Andy

[Jen]

I can see how mixing by weight would appeal - just like cooking, you don't have to measure anything out, just bung it in until it weighs the right amount.

If Perpetua's calculator is Excel, you just program it to convert to g in that column. But you never know, she might have a template for you

[lemental]

Jul 25, 2013 8:13:07 GMT chykensa said:

I'm not quite sure what the advantages are of you mixing by weight. As everything is liquid, surely the best and most efficient way to mix is by mililitres (or even drops if you are working in really small quantities).
Accuracy using syringes can be really quite precise, and at the end of the day, a drop either way won't make a massive difference and mess up a recipe.
Andy

The way I see it, if I know the exact density of a liquid, have a set of accurate and calibrated scales, I don't need syringes or other types of volume measuring equipment.  This was the main appeal.

As Jen says, it's simplicity.  Just a case of plonking an empty bottle on the scales and adding each ingredient from its dropper bottle until I've reached it's desired weight.  I've experimented with drops and found it very inconsistent, being dependant on the viscosity of the liquid and the type of dropper.  Also when I'm making small samples, the recipe is pretty accurate.  I do understand that a drop here or there won't make much difference but I'm a bit anal when it comes to things like this!

[Jen]

OK, I'm not amazingly brilliant at maths and am very thick when it comes to physics and chemistry - do you really need to know the density for measuring by weight? If most flavourings are suspended in PG, wouldn't they be roughly similar? Or at least, would you not get the same result as measuring by ml?

So you could measure out 1ml of flavouring in a syringe, weigh that and then use that calculation as a basis for your Excel spreadsheet, right? I have to say, this method is beginning to appeal to me, too - taking all the droppers off the bottles to get the syringe in is annoying

[chykensa]

Not sure but VG, PG, and flavourings might all have different densities though. Using a syringe means you only have to worry about volume, not calculating with possibly 3 different densities. I can't help feeling that you are making life unnecessarily difficult for yourself.
It's a bit like mixing concrete by weighing the ingredients rather than adding by percentage - you are adding another stage which is not needed.
Andy

[Jen]

I might get some precision scales and do some science. Only one way to find out, really!

[lemental]

Jen Yes, you do need to know the densities (specific gravities) for measuring by weight but you don't need to be good at maths

1ml water weighs 1g
1ml PG weighs 1.036g
1ml VG (undiluted) weighs 1.261g

All I do is use a standard calculator to convert the ml I get from a juice calculator to grammes. No need for 3 decimal places but I've just put them there as they're the book values.

As the concentrates are mainly PG based, you can just use 1ml=1.04g as you do with PG.  Any difference made by other components of the flavour are very negligible.

I've verified the densities using scales and a 100ml measuring cylinder and was 0.2% off with the VG and less with PG so the figures are accurate. If you weigh a small amount like the 1ml you mention, you won't get the same accuracy as measuring out a large amount and weighing.

If do want to use weights, it's worth getting some calibration weights and using them every now and then to make sure the scales aren't lying.

If you measure accurately by ml you'll get exactly the same result but as I mentioned earlier, this method makes it much more convenient for me, not having to use anything more than scales and nothing to wash up afterwards! 

[lemental]

I didn't intend for this thread to be a debate of volume vs weight but I thought it may happen

[Jen]

Interesting! Anything to reduce the washing up

Off to look at some scales on eBay...then to knock up an Excel spreadsheet to do all the heavy maths lifting for me

[lemental]

When you get scales, get some that measure to 0.01g resolution and I'd say a maximum weight capacity of 200g. Usually to calibrate scales, you need to buy a weight or combination of weights that add up to the maximum weight capacity so if you buy 1kg scales, you'll need a 1kg weight and they aren't cheap!!

Also some of the very cheap scales aren't very good. These are the scales I use which have been surprisingly accurate for the price.  They also react much more quickly than other scales I've had.   I originally bought them for weighing coffee beans but now they have another purpose!!

www.ebay.co.uk/itm/0-01g-200g-Digital-Mini-Pocket-Jewelry-Gold-Coin-Scales-Scale-Weigh-DB-OT9902-/300915930586?pt=UK_Jewellery_Watches_JewelleryBoxes_Supplies_CA&hash=item460ffcb5da

[Jen]

Awesome - will have a go at the spreadsheet this afternoon, just got a bit of deadline this lunchtime. If I manage to produce something decent, I'll let you know

It will involve using EMJU-produced values, though, you can probably do something similar yourself I'm nowhere near good enough to make my own EMJU-like calculation!

[lemental]

Thanks Jen. No rush! If it just involves manually plugging in the ml and excel calculating the weight, I'm OK with that but it would be good to see something more fancy

Ideally I'd like to see a calculator like EJMU that lets you put in your own ml:g ratios and does everything else that EJMU but I don't think one exists.

[Jen]

OK, very basic ml to g calculator for starters:

docs.google.com/file/d/0B7X9sKmbHXUgczYwVDhqRXN6d1E/edit?usp=sharing

Hope that works!

[lemental]

Great stuff Jen When I get the time and patience, I'll probably work on a full calculation spreadsheet in Excel or just modify one that's already available with permission from the creator.