The SN has already been tested in a lab and its purity has already been determined before it is sold. It's required by law to be tested before it can be graded and sold. The purity listed on the label is accurate and can be trusted. When it is tested in a lab, it is given a certificate of analysis telling you exactly the quality and purity of the substance. Any reputable company will give you a copy of the certificate of analysis of their product, so there is no question of what you are buying. This analysis is done by an independent lab not by the company that sells it. If someone buys SN and the label says it is 99 percent pure SN, it is. There is no reason for them to lie. No one is putting a different substance in the bag and labeling it as SN or misrepresenting it's purity. It's not really necessary to further test the SN if you buy it from a reputable company. You can contact the company, and they will give you the COA from the lab that tested it. Saying that someone is unable to know the exact purity of the product is inaccurate.
I understand what you are saying and makes sense to me. I know if companies want to market their product and label it as being a certain percentage of purity, then they will get it tested by an independent lab... Like you said. However, not all products are created equal. That is, some companies (not those in the UK, USA or Canada for example) which are located in more economically challenged countries may not hold their products to the same rigorous standards compared to more developed countries. Why? I don't know. But, it actually may happen. I'm not telling everyone to doubt the quality of their SN, but at least test it with methods which we can then infer it's purity. Again, making a solution with a specific concentration and then testing it with test strips doesn't directly confirm purity. The color changes on strips are very subjective. On some, the color shade between one concentration and the next are quite minute which can lead to confusion about purity.
I want to address your statement that "No one is putting a different substance in the bag and labeling it as SN or misrepresenting it's purity". I would have to agree with you for the most part. However, there was a case somewhere in the forum about a failure of their "supposed" SN to help them to CTB. The poster actually used a product from a
reputable seller, but failed even though he followed a particular regimen. He/ she posted pictures of their SN in the bag it normally comes in. Well, the product did not even look like SN from that particular company and many people commented on that. The crystals were totally white, almost see through. It was not small, granular or yellow tinged like the SN they normally sell. So, how did he/she get a product that does not even look anywhere close to the SN they normally sell? Could it be a one-off thing... possibly. But that would be a great error because these things are made in batches. I don't know where to find the thread just yet.
Update: found the thread at https://sanctioned-suicide.net/threads/failed-sn-not-sure-why.92077/page-8
I'm not saying the company intentionally provided a faulty product because even the poster could have possibly been untruthful.
I don't think it's inaccurate to say we can't know the purity. I don't have access to a lab and use methods such as chromatography or spectroscopy to determine it's purity. Do you? What I'm getting at is that we, as consumers, expect things as they are advertised without question because that's all we can do. We either place faith in something or we don't. Most people can't go around conducting tests to ensure that something is truly what is claimed. With regards to SN, I'm sure most claims are true from reputable companies. But we can't extrapolate this to each company in the world that sells SN.
