I have some Limestones full of fossil including fish teeth. Traveling all over our small home town to find the strongest "vinegar" I could, and first I saw a gallon at the supermarket was 5%. Pickling vinegar at Walmart - 5%. Cleaning vinegar at Home depot - 6%. They advertise on their web site 30% called "Ultra Vinegar" but no one in the store has a clue. Ive heard that 10% is what is used on the Gogo stuff. Please give me your thoughts, thanks!