Will Price Posts About

Custom etch tank: The start.

I've decided to have a bash at making an etch tank as I like making PCBs, however at the moment I've got no way to heat my etchant up and the whole affair is looking like a rather sorry state. After reading this instructable, I decided to build my own, I really like the etch tank design but would like to redesign it myself, purely for the practice in CAD and in-depth knowledge it will provide. I've bought an aquarium pump and heater to use in it and I will be using cupric chloride to etch.
I've found a wonderful website with a list of several materials and their resistances to specified chemicals, it's really invaluable to picking materials to use.
So far I have chosen a few materials:

Etch tank - Acrylic
Tubing - Ideally polypropylene (but I will settle for PVC) 1/4" ID (same as aquarium pump)
Fittings - Ideally polypropylene, but if PVC one are available I'd settle for them, they're expensive and hard to find.

It's a rather pitiful list but it's all I've decided on for the moment. I'm looking at buying chemicals, shipping is painfully expensive and I haven't really calculated how much I need to get, so that's on my to do list. It looks like higher concentration solutions of hydrogen peroxide cost the same as the lower concentration ones, obviously I'll go for the higher concentration as It's less to store, shipping will be cheaper and It's easy to dilute it.

I also need to get some methylene chloride for solvent welding acrylic, it's pretty cheap here, but I might buy it from ebay depending on delivery prices, this seller has most/all of the chemicals I need. Scratch that, the first seller mostly what I want at lower prices, excellent!
Hydrogen peroxide is the only thing that isn't stocked there, I thought I'd figure out how much I need, at 35% it's pretty concentrated, I used this handy calculator to find the concentration in mol/dm^3, so 500ml at 35% can be diluted to give 5 litres of 1.16mol/dm^3 looking at the equation on the cupric chloride link:
2H+ + Cu1+ + O{aq} → Cu2+ + H2O
This looks like it's probably going to be more than sufficient. Actually looking at the page again, it just occurred to me, I don't even need hydrogen peroxide after producing the etchant as I can regenerate the solution using air, I'm going to just get 250ml...
The acid gets used up so I'm buying a litre of that, the common mix to produce the starter etchant seems to be:
1 part HCl (35%)
2 parts H2O2 (3%)

Just bought:
1 Litre HCl
1 Litre Acetone
1 Litre methylene chloride
1 kg NaOH (just in case I want to do titration and analyze my etchant)
£9.50 for delivery
£11.50 for the chemicals

Now I can whip up some etchant, have a play around with it and see whether the check valves I've bought are or are not made from polycarbonate... hopefully they'll be OK.

On a side note: I've picked up a laser printer (from freecycle!) which I may play around modding to print on circuit boards. However, it looks like a fairly complicated endeavour which currently I'm not sure I need to embark on, one for the future perhaps.