Measuring tiny amounts of salts

I brew 1 gallon batches and my water seems pretty close to what I want, only minor adjustment needed. For example, my next brew needs 0.7 grams of CaCl. This is going to be hard to measure with the equipment I have.

I was thinking, what if I made up a solution of 500ml water with 5g CaCl (ie 1g per 100ml) then measure out 70ml of that solution to get my 0.7g of CaCl? I trust my equipment to measure 5g and 70ml within reasonable limits.

If I gave the solution a good shake to mix thoroughly is there any reason why this wouldn't work?

Or, any other tricks for measuring small amounts of salts? I have a better 0.1g scale on order but that's a few weeks away still.

Yeah, that will be OK

But there are lots of scales on TM with 0.01g precision, thats where I got my hop scales from. I assume they are good for other green things too, hence their popularity on TM.
ipe:
eg
http://www.trademe.co.nz/home-living/kitchen/scales-measures/auction-1169270948.htm

This is a particularly good way to handle CaCl2 as you don't need a scale at all if you have a hydrometer. See the Sticky above for details.

I have ordered a .1 x 2kg scale off Aliexpress, thinking it would be good for hops and grain (my grain bills are normally about 1kg). This was before I got my water report and did the calcs.

My experience with these cheap electronics is that the extra digit is just for show anyway. My thermometer is accurate to 0.1 degree yet still thinks that water boils at 110.

Sadu said:

My experience with these cheap electronics is that the extra digit is just for show anyway. My thermometer is accurate to 0.1 degree yet still thinks that water boils at 110.

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Your experience is not mine. I've owned 4 or 5 different scales, some with a 0.1g resolution and some with a 0.01g resolution, and by far the 0.01 resolution scales are incredibly accurate and hold their calibration insanely well. That's not to say that there are some cheap ones that aren't great out there, but my $11 one from Amazon with 0.01g resolution has been extremely reliable thus far.

Make sure you check the margin of error. I have seen some 0.01g resolution scales with margin of +/- 0.1g - so in that case yes the extra digit is for looks and not much else. My current 0.01g scale has a margin of +/- 0.02 and I feel it is usually even more accurate than that.

The question for you gents is "How do you know the scales are accurate, or innacurate?". The right answer is "I calibrated it against standard weights."

Yes sorry neglected to mention that part. One scale I have came with a 5g, 20g, and 100g calibration weight. Now I just use the top/cover of the scale each time to gauge if it needs calibration (14.24g +/- 0.01).

You guys got me worried, so I checked my scales with some coins. Reading consistently about 1% high from 3g (10¢NZ = 3.30g).

I'll adjust my hop schedule accordingly.

So 10c NZ is 3g? That is good to know. Will have to give that a try, in the absense of real weights.

10¢: 3.30g

http://rbnz.govt.nz/notes-and-coins/coins/new-zealand-coinage-specifications

Sadu said:

I have ordered a .1 x 2kg scale off Aliexpress, thinking it would be good for hops and grain (my grain bills are normally about 1kg). This was before I got my water report and did the calcs.

My experience with these cheap electronics is that the extra digit is just for show anyway. My thermometer is accurate to 0.1 degree yet still thinks that water boils at 110.

Click to expand...

Your water may boil at 110°F if your elevation is 1,800 to 2,000 feet. There is approximately a 1°F drop in the boiling point of water for every 500 foot increase in elevation above sea level.

flars said:

Your water may boil at 110°F if your elevation is 1,800 to 2,000 feet. There is approximately a 1°F drop in the boiling point of water for every 500 foot increase in elevation above sea level.

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Uhhh.....no I don't think so. Water boils at 212°F at sea level. At 2K ft, it would be about 208°F. I think you're off by about 100°F.

I believe Sadu is using °C since he also reference kg instead of lbs. In that case he is saying his thermometer reads 110°C when it should read 100°C. Unless he is about -9,000ft below sea level. Which would be amazing.

yeah I meant 110c. Since I live above sea level I figured it was my $3 thermometer that was the most likely out.

As a side issue - I was totally blown away to learn that water boils at 99c in my region, not 100c. Learning new tricks every day.