How do you dispose of exhausted etch liquid?
 

How do you get rid of exhausted etch liquid?

I assume given all the warnings for use on the bottle you can't just dispose of it in normal household rubbish or tip it down the drain.

Most etch liquid is trifluoriacetic acid. It nasty stuff

Here a link to the msds
http://www.jtbaker.com/msds/englishhtml/t5525.htm

and here's the paragraph on disposal
13. Disposal Considerations
Whatever cannot be saved for recovery or recycling should be managed in an appropriate and approved waste facility. Although not a listed RCRA hazardous waste, this material may exhibit one or more characteristics of a hazardous waste and require appropriate analysis to determine specific disposal requirements. Processing, use or contamination of this product may change the waste management options. State and local disposal regulations may differ from federal disposal regulations. Dispose of container and unused contents in accordance with federal, state and local requirements.

Wouldn't dumping a bunch of baking soda in the bottle neutralize the acid making it less hazardous?

Would it?

It would neutralize the acid so it wouldn't corrode your pipes, but the fluoride in it is the problem. We used to use it to superclean lab glassware in college, and there were lots of rules and regulations about its disposal.

Do NOT dump baking soda in the jar! You would get volcano type action and spattering. How much do you need to dispose of? I can probably come up with a safe way to neutralize it. Etch All Dip-n-Etch is a 20% solution of ammonium bifluoride.

Here is a link to the material safety data sheet for Etch All cream. I couldn't find one for the liquid, but it would be very similar:
http://www.alpineglass.com/shop/imag...lCreamMSDS.pdf

The disposal section states that moderate amounts can be flushed down the sanitary sewer system with plenty of water - flush with water or neutralize with lime.

I would make a saturated solution of baking soda in water about twice the volume of the etch all (just keep dumping baking soda into the water until it doesn't dissolve anymore). Wear eye protection and gloves. Slowly add the etch-all to the baking soda solution a little at a time. It will fizz and bubble. When it's all neutralized you can pour in down the drain slowly with lots of water.

You probably don't want to flush the stuff into your system if you are on a septic tank.