Product Instructions:1. Checking the Property of the Solution: please take a small piece of test paper on the surface of the glass or vessel, use the glass rod or plastic dripper with stain to point in the middle of the test paper, observe the color changes and compare it with the color card, and determine the property of the solution.2. Check the Property of the Gas: firstly please wet the test paper with distilled water, stick it to one end of the glass rod, close the paper by glass rod to the gas, observe the color changes, and determine the property of the gas.Attention:(1) The test paper can not be directly dipped into the solution.(2) The test paper can not touch the test tube mouth, bottle mouth, catheter mouth and so on.(3) When you are measuring the pH of the solution, the test paper can not be previously wetted with distilled water, because the wetting test paper is equivalent to diluting the test solution, which can lead to inaccurate measurement. The correct way is to dip in the middle of the test paper by glass rod with solution to be tested. After the test papers; discoloration, then you can compared it with the standard color card to determine the pH of the solution.(4) After taking out the test paper, the lid of the container which contains the test paper should be tightened to avoid contamination by some gas in the laboratory.Product Parameters:1. Thickness: of Each One: about 0.2 mm / 0.01 inches2. Note: 80 pcs / book with color card3. Material: paperPackage included:1*set Note: 1. Please allow 1-3 mm error due to manual measurement and 1-3g weight error make sure you don't mind before ordering. 2. Due to the lighting of the photos and the difference of monitors, the pictures may not reflect the actual color of the real item. Please make sure you don't mind before ordering, thank you! About Shipping: 1.please pay attention to your delivery address such as: name, street, house number, doorbell/email without name, etc. is correct, or the order will not be delivered correctly. 2.All items will be shipped within 3 business days after the payment is received. Most times you will receive them within 8-12 days then. The specific delivery time is depend on circumstances. 3.During the shopping process, if you have any questions, please feel free to consult us, we will reply you within 24 hours Hope you have a pleasant shopping experience!