It's an Acaia Pearl Coffee Scale. A stupidly over-the-top expenditure for the coffee obsessed, like me. It's Bluetooth-enabled to integrate it with a smartphone app. New features and I think a Bluetooth update.
Ziplock Mylar/Aluminum Foil Ziplock bag performance test
- Thread starter craiginthecorn
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Actually, it was a gift from my daughter.
I also don't need a Jess Chonowitsch pipe to smoke my tobacco when a cob would suffice, but it's a passion and I enjoy both the Jess pipe and the Acaia scale.
I also don't need a Jess Chonowitsch pipe to smoke my tobacco when a cob would suffice, but it's a passion and I enjoy both the Jess pipe and the Acaia scale.
Accuracy of a scale is important, but so is repeatability. Accuracy is a function of calibrating a scale with very good repeatability to a known standard. But a scale could have very good repeatability, but not be accurate. That's perfectly acceptable for what you are doing, where you are looking for deviation from a standard.
I'd kindly suggest that you need to have a reference weight that is closer to the weight of the Mylar bags and the jars. Then check your scale multiple times with those reference weights. That will tell you if your scale has good repeatability (precision).
The fact that the accuracy has already shifted isn't a good sign.
I'm not surprised that the Mylar bag lost moisture, most likely through the zip seal. This experiment would be more useful though if you controlled for the zip seal by also including a tobacco sample in heat-sealed bag of the same type.
Which brings up another thought: Are you conducting this trial with just one bag and one jar? You should have a much larger sample, to keep an anomaly defect from skewing the results.
As for the jar losing moisture, I'm at a loss to explain that. If the lid is screwed down tight, and the seal is clean and uniform, there should be zero loss.
I'd kindly suggest that you need to have a reference weight that is closer to the weight of the Mylar bags and the jars. Then check your scale multiple times with those reference weights. That will tell you if your scale has good repeatability (precision).
The fact that the accuracy has already shifted isn't a good sign.
I'm not surprised that the Mylar bag lost moisture, most likely through the zip seal. This experiment would be more useful though if you controlled for the zip seal by also including a tobacco sample in heat-sealed bag of the same type.
Which brings up another thought: Are you conducting this trial with just one bag and one jar? You should have a much larger sample, to keep an anomaly defect from skewing the results.
As for the jar losing moisture, I'm at a loss to explain that. If the lid is screwed down tight, and the seal is clean and uniform, there should be zero loss.
[As for the jar losing moisture, I'm at a loss to explain that. If the lid is screwed down tight, and the seal is clean and uniform, there should be zero loss.]
I agree because should be true jar is losing >5% in 6 months this would defeat all theory of using jars for long term storage. I think you should be careful and double check with jar measurement
I agree because should be true jar is losing >5% in 6 months this would defeat all theory of using jars for long term storage. I think you should be careful and double check with jar measurement
I agree, Woods. Thanks for the feedback and suggestions.
I had been thinking that I should have included more samples. I may well do that since this is a long-term test. I also thought about how it would have been interesting to include a heat-sealed sample. That would help to determine if the moisture loss is primarily due to the ziplock or the material itself. For me, that question is purely academic since I'm using the bags for stable, short-term storage of tobaccos I'm currently smoking. Others are using heat-sealed bags for long-term storage, however, so I think I'll include a couple of those too.
Regarding the scale, it has been shown in independent tests to be highly precise, but like virtually all modern scales, it requires periodic calibration. It is in wide use by baristas. I hadn't bothered with that for my coffee-making and cooking purposes. I figured it was more accurate than I could possibly need. I now have a set of precision reference weights which I can use to calibrate the scale myself.
As for the reference weight, I chose 20g because it matched the weight of the tobacco samples. There's a huge difference in weight between the bag and the jar, so a single reference would be hard to pick. I think I'll continue to use the existing reference weight for this experiment, just to be consistent. I'll calibrate the scale with a 100g weight, which falls between the weights of the bag and the jar.
The only thing I can imagine with the jar is that since these were mechanically sealed and not vacuum sealed by boiling, maybe there's been a bit of breathing from temperature changes or gas escaping from fermentation or off-gassing of some sort, carrying some moisture along with the gas. Still, .2g is a surprising total. I expect that the jar will remain relatively constant now and that the bag will continue to exhibit moisture loss.
I had been thinking that I should have included more samples. I may well do that since this is a long-term test. I also thought about how it would have been interesting to include a heat-sealed sample. That would help to determine if the moisture loss is primarily due to the ziplock or the material itself. For me, that question is purely academic since I'm using the bags for stable, short-term storage of tobaccos I'm currently smoking. Others are using heat-sealed bags for long-term storage, however, so I think I'll include a couple of those too.
Regarding the scale, it has been shown in independent tests to be highly precise, but like virtually all modern scales, it requires periodic calibration. It is in wide use by baristas. I hadn't bothered with that for my coffee-making and cooking purposes. I figured it was more accurate than I could possibly need. I now have a set of precision reference weights which I can use to calibrate the scale myself.
As for the reference weight, I chose 20g because it matched the weight of the tobacco samples. There's a huge difference in weight between the bag and the jar, so a single reference would be hard to pick. I think I'll continue to use the existing reference weight for this experiment, just to be consistent. I'll calibrate the scale with a 100g weight, which falls between the weights of the bag and the jar.
The only thing I can imagine with the jar is that since these were mechanically sealed and not vacuum sealed by boiling, maybe there's been a bit of breathing from temperature changes or gas escaping from fermentation or off-gassing of some sort, carrying some moisture along with the gas. Still, .2g is a surprising total. I expect that the jar will remain relatively constant now and that the bag will continue to exhibit moisture loss.
More thoughts on the jar. As I mentioned in my initial 6-month update, much of the jar's weight loss could be due to rounding error. This scale is precise to the 10th of a gram. Let's pretend that the jar initially weighed 163.75g and now weighs 163.64g. That would have resulted in scale readings of 163.8g and 163.6g. In this extreme example, a .11g drop in weight appears to be .20g drop -- almost double the actual amount.
Craig, in case you can’t tell, I’ve thought about doing similar testing myself. I usually ponder such things on my daily dog walks. What starts out as simple trial as I head up the driveway, quickly escalates into a full-blown research project as I near the half-way point on my walk. Monitoring temperature, humidity and pressure inside the containers, and controlling the same outside is always a complicating issue. That leads to questions about the gasses inside the containers, and how they change over time. By the time I’m back home, I’ve reached the realization that finding funding for my Tobabacco Studies Lab isn’t going to be easy, and that even if I can find lab coats for my dogs, they are only going to be interested in assisting with the project if it involves squirrels.
Keep the thoughts coming, Woods. I'm trying to be methodical, if not exactly scientific in my approach. Hopefully, the results will help some folks.
I think it's a lot easier to measure moisture loss directly, i.e., hygrometers or moisture meters if you have the money. If you go the $5.00 ones, you should use two per sample as they aren't exactly scientific grade.
I've wondered how much moisture by weight is in a two ounce tin at 90% RH vs one at 70%, both at 70º. If anyone can tell me it's you guys.
I've wondered how much moisture by weight is in a two ounce tin at 90% RH vs one at 70%, both at 70º. If anyone can tell me it's you guys.
I pack my jars fairly tight and leave little head space . The thought being it reduces vapour pressure and therefore less water loss. I can’t see glass having permeability , so if there is any exhange it would be around the seal .
Those military spec bags for MREs designed for ten year storage , pretty sure we could find permeability data online Vs mil thickness for example. I also seem to recall they are vacuum sealed , reducing vapour pressure .
Those military spec bags for MREs designed for ten year storage , pretty sure we could find permeability data online Vs mil thickness for example. I also seem to recall they are vacuum sealed , reducing vapour pressure .
Another thought , I have a waterproof 200m water proof Russian watch. There is an online video of a watchmaker giving instruction on how to seal it up , better than factory spec.
He uses a thin coat of silicone oil on the gaskets . Thinking improved gaskets on mason jars would be something to experiment with.
He uses a thin coat of silicone oil on the gaskets . Thinking improved gaskets on mason jars would be something to experiment with.
Measuring moisture content in tobacco with a meter is tricky business. In the current edition of NASCP's The Pipe Collector, I co-authored an article with my good friend, Mike Zicha which examines how moisture content and bowl size affect the smoke.
One challenge we faced was how to accurately measure moisture content. We had a basic moisture meter but quickly discovered that getting consistent readings was very difficult because of how they work. Essentially, they're an ohmmeter, measuring electrical resistance between two probes. So, the more compressed the tobacco, the lower the resistance, which results in higher moisture readings.
I had been corresponding with Greg Pease about how these measurements were done in the tobacco industry and quickly determined that it was far too costly and expensive for our research. When I shared with Greg the problem we were having with consistency, he recommended measuring a fixed weight of tobacco in a fixed volume. That greatly improved repeatability, but we had to be satisfied with a repeatable approximation.
A more reliable method for measuring the relative changes in moisture is by weight. For the purpose of this test, I assumed the tobacco's starting moisture by weight to be 17%. In all likelihood, that's a little low, but at the time I started this experiment, I knew nothing about measuring hydration. Let's assume that I had 100g of tobacco, I'm guessing that it contained 17g of water at the start. If half its moisture is lost, leaving the tobacco almost crispy, the tobacco's weight would drop by 17*.50, or 8.5g. The weight of the tobacco would then be 91.5g.
One challenge we faced was how to accurately measure moisture content. We had a basic moisture meter but quickly discovered that getting consistent readings was very difficult because of how they work. Essentially, they're an ohmmeter, measuring electrical resistance between two probes. So, the more compressed the tobacco, the lower the resistance, which results in higher moisture readings.
I had been corresponding with Greg Pease about how these measurements were done in the tobacco industry and quickly determined that it was far too costly and expensive for our research. When I shared with Greg the problem we were having with consistency, he recommended measuring a fixed weight of tobacco in a fixed volume. That greatly improved repeatability, but we had to be satisfied with a repeatable approximation.
A more reliable method for measuring the relative changes in moisture is by weight. For the purpose of this test, I assumed the tobacco's starting moisture by weight to be 17%. In all likelihood, that's a little low, but at the time I started this experiment, I knew nothing about measuring hydration. Let's assume that I had 100g of tobacco, I'm guessing that it contained 17g of water at the start. If half its moisture is lost, leaving the tobacco almost crispy, the tobacco's weight would drop by 17*.50, or 8.5g. The weight of the tobacco would then be 91.5g.
I agree . But to my mind , tight can be improved with a thin coat of lubricant , a microscopic roller bearing , allowing the lid to lock down a bit more . Plus a plumbers strap wrench or oil filter wrench to torque it down good.
Things I have made gaskets out of ... neoprene rubber , the stuff found in wet suits ... ptfe tape or sometimes I use plastic milk bags ..., and , copper , my Volkswagen fuel lines had copper gaskets which , when heated slightly and then compressed under the fitting , sealed up good .
..in my lab when preparing field samples like filters , the procedure was to bake them at around 200C for 24 hours voltailizing all water , then store them to cool in a bell jar with a dessicant for 24 hours . Knowing the before and after weights determines what the filter holds , including water content . Repeat the procedure after sampling and reweigh the filter gives the sample data .
But of course we used calibrated microbalances on bedrock to get 5 digits after the decimal.
OK, so the problems with these methods are that they don't actually measure moisture content directly. A hygrometer measures moisture in the air. There are a multitude of reasons why a given sample will not reach moisture equilibrium with the air surrounding it. Humectants, density of the sample (the outside dries out first, inside stays moist), volume of air...lots of reasons. A moisture meter, as has been mentioned above, measures conductivity between two electrodes. That works OK for lumber, but not too well for shredded tobacco.
But, lo and behold, there is a specialized piece of lab equipment called a moisture analyzer that makes this task pretty darned easy.
Take a 1.00 gram sample and measure it on a triple beam balance , repeatability will be good compared to those electronic balances using a strain gauge . They are not linear , meaning the specs change depending on the mass on the pan.
You can find a good old fashioned analog balance at a high school science lab or check with any drug dealer from the 70s
You can find a good old fashioned analog balance at a high school science lab or check with any drug dealer from the 70s
Ha!
I have an old Ohaus triple beam, and an Ohaus Dial-O-Gram. I got them from my dad, who taught college sciences. He got them when the school that he worked out tossed them in favor of the sexier-looking digital scales that looked better when prospective students and their parents took the campus tour. Back when I used to mix my own photo chemistry, I was using them all the time. Now, when I make soap, I use a digital scale. Shame on me.
I have an old Ohaus triple beam, and an Ohaus Dial-O-Gram. I got them from my dad, who taught college sciences. He got them when the school that he worked out tossed them in favor of the sexier-looking digital scales that looked better when prospective students and their parents took the campus tour. Back when I used to mix my own photo chemistry, I was using them all the time. Now, when I make soap, I use a digital scale. Shame on me.
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