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Subject: Re: [Homebrew_PCBs] Re: Etching container

From: DJ Delorie <dj@...>
Date: 2010-06-08

On 06/08/2010 01:42 PM, Leon Heller wrote:

>> Where do you get sodium hydroxide?
>> Also, is your disposal method the "official, recommended" method of disposal?
> Just pour it down the sink, it's used as a drain cleaner.

Warning: don't store sodium hydroxide (NaOH) in plastic soda bottles.
Mine finally gave way last weekend, had a tub full of 1M NaOH (yes, I
keep it all in a catch-basin, and good thing too). Plastic is organic -
NaOH dissolves organics - duh. It still took about a year, though.

Sodium Hydroxide can be poured down the drain, yes. It won't harm metal
drainpipes, and won't dissolve PVC that quickly. Etchant will dissolve
metal pipes eventually, but will leave PVC alone. In either case, ∗if∗
you pour anything down the drain, ∗first∗ dilute it a lot, and run the
water for a while after to rinse the drain system out and further dilute it.

Your local waste transfer station can tell you what your other options
are. Ours has an annual hazardous waste day for such things.