Information on sun tan lotion is easy to come by. Every manufacturer of tanning products will tell you exactly what their product is designed to do. Be prepared for a slight exaggeration from most companies, but for the most part, they are honest.
You can find information on sun tan lotion on the bottle. They will tell you what they made the product to do. It might not work as well as they say nor have the affects they promise. But, in some cases, it does mean that.
In the sun tanning industry, you can take most things for face value. Companies will try to be honest so that they get customer loyalty. If they say one thing and do not deliver, they are going to get a bad reputation and will not have any repeat customers.
The best advice you can go by is to just use name brand products. They have developed a reputation and have been in business for a while. That means that they have to do what they say. Avoid the generics and you are going to be fine.