Wow, glad you asked this question. I just Googled Instructions for Using Drano and found a site with all kinds of instructions. Here's the link and some information that will answer your question.
Thanks to its unique churning action and heat, Drano® Kitchen Crystal Clog Remover is the product you need when you've got a stubborn kitchen clog. Its granular formula melts most grease clogs in minutes, but it's also great on hair, soap scum, and other debris that blocks your drains. And because you only need a small amount to get the job done right, a single container of Drano® Kitchen Crystal Clog Remover lasts a long time. Note: If your kitchen sink has a garbage disposal, do not use Kitchen Crystals Clog Remover. * Best on grease and kitchen clogs * Safe for all pipes, septic tanks, and cesspools * Contains no phosphorus * Drano® Kitchen Crystal Clog Remover interacts with cold water. * The heat from the mixture works to melt and break down greasy clogs. * A final blast of cold water flushes away what's left of the clog. * Remove any standing water. Make sure water in drain is cool. If possible, remove drain strainer. * Pour one heaping tablespoon (30 grams) of Drano® drain openers into drainpipe. Securely close lid on can. In case of spills, sweep into dust pan, empty down nearest drain and pour cold water down the drain. * Immediately add one cup of cold water to drain (if water boils out of drain, add another cup of cold water). Rinse spoon immediately after use. * After 15 minutes, pour cold water down the drain. If drain is still clogged, repeat application. Do not repeat after second application. Consult a plumber. For Floor Drains: Follow the same procedure but use 3 heaping tablespoons (90 grams) of Drano® drain openers and add 3 cups of cold water. * Use one tablespoon weekly as directed to keep drains running freely. Never cover drain. Keep hands and face away from drain and children away from sink area. Keep Drano® drain openers and solutions of Drano® away from eyes, skin and clothing. Keep water out of can at all times to prevent contents from violently erupting or boiling out. Never use or mix with other drain cleaners or chemicals before, during or after using Drano® drain openers since Drano® may still be present if drain did not completely clear and Drano® may react with such products. Never use with plunger or pressurized drain opener (splashback of lye can occur). Even after use, Drano® drain openers may still be present if drain did not completely clear. Do not use in garbage disposers, dishwashers, toilet bowls or in pipes directly connected with such devices. Keep off all surfaces, fixtures and utensils made all or in part of aluminum, wood, paint, acrylic or fiberglass. http://www.drano.com/clogged-kitchen-drain/ Original Message: Good day, I wondered if anyone might have the specific instructions for Drano crystals? I know the general concept but its been a few years since I used this kind of Drano and the sighted person I was with when I bought it couldn't read the instructions because they were printed too small. Thanks for any help, Yours sincerely, Joy [Non-text portions of this message have been removed]