Soda Ash Weight vs Volume

[spsick]

Recently picked up 2x 7lb bags of BRS soda ash on sale and noticed one considerably more full than the other but confirmed weight is 7lb on both. Like 1 is chock full and 1 has 25% empty space. Been using it since forever but never bought 2 bags at the same time to notice the difference. Is it just moisture content?

Being the instructions call for 2 1/3 cups vs weight to make a gallon, will my solution have a meaningful difference in strength from 1 bag to the next?

@Randy Holmes-Farley?
@Bulk Reef Supply?

 

[Miami Reef]

Following. This will be an interesting and informative thread. :)

 

[spsick]

DOH, answered my own question. One of the bags has a damaged seam on the top probably from shipping as the corner is crunched so I’m guessing it’s sucked in moisture.

 

[Sean Clark]

I was hoping for a more dramatic ending. Kind of glad there wasn't though.

Good to recognize that moisture incursion could result in a more dilute concentration though.

 

[Randy Holmes-Farley Verified Community Expert]

In answer to the original question, there is not ever a single value that relates mass to volume for all powders of the same chemical composition. It depends on many factors such as particle size and distribution, and how much one allows the materials to try to pack together.

It is an attribute called "bulk density". BRS actually discussed with me once an issue relating to bulk density and directions that may have to be changed when different suppliers are used.

FWIW, you can look up bulk density for a single product made by a single manufacturer and usually have good confidence in it, but not if you try to extend to other suppliers.

Here's an example for sodium bicarbonate. Even for a single brand they give it as a range.

"Bulk Density Poured Typical Range: 63 - 75 lbs / ft3"

https://naturalsoda.com/wp-content/uploads/2018/08/AMM-NS-USP-5-TDS.pdf

 

[spsick]

In answer to the original question, there is not ever a single value that relates mass to volume for all powders of the same chemical composition. It depends on many factors such as particle size and distribution, and how much one allows the materials to try to pack together.

It is an attribute called "bulk density". BRS actually discussed with me once an issue relating to bulk density and directions that may have to be changed when different suppliers are used.

FWIW, you can look up bulk density for a single product made by a single manufacturer and usually have good confidence in it, but not if you try to extend to other suppliers.

Here's an example for sodium bicarbonate. Even for a single brand they give it as a range.

"Bulk Density Poured Typical Range: 63 - 75 lbs / ft3"

https://naturalsoda.com/wp-content/uploads/2018/08/AMM-NS-USP-5-TDS.pdf

Thanks Randy. So in such a case measuring by weight would probably have a lower margin of error and thus strength variability?

 

[Randy Holmes-Farley Verified Community Expert]

Thanks Randy. So in such a case measuring by weight would probably have a lower margin of error and thus strength variability?

Yes, measuring by weight is better in most cases,, but not perfect since many chemicals can have different levels of moisture in them.