Hang on! You can’t just go putting acid on to your skin. What is the pH of that acid? Is it buffered? Is it partially neutralised? Is it all free acid? What percentage lactic acid is it? I really do not advise that you just go putting an acid on your skin… you NEED to know all of these particulars before you can even think of proceeding. Are you sure that lactic acid is the correct ingredient for your skin’s specific needs? I would strongly advise that you take that product to your aesthetician or you aesthetic doctor and let them have a look at it first and let them advise you from there, while you are with them.