Roll your own etchant

Peroxy-sulfuric etchants are made to run in a temperature range from 110° (immersion baths) to 120° (air agitated and spray systems). The lower temperature is recommended for immersion baths that do not employ some means to remove the heat that is generated during copper etching. Excessive heat build up in such a system can lead to a catastrophic exothermic reaction that can damage, or destroy, your etching tank and sparger (not to mention your PCB shop). Air agitation or spraying of the etchant during operation removes a significant amount of heat from the bath, requiring a higher initial operating temperature.

As you use the recipes below, be advised that many vendors only carry 35% (or 50%) hydrogen peroxide in 55 gallon drums and you may have to pay as much as $100 in HAZMAT charges to have it delivered.

Bulk Etchant Recipes
Mix components in the order presented!
Type	Component	Concentration by volume
I m m e r s i o n	deionized (or distilled) water	41%
	35% sulfuric acid (car battery acid)	29%
	Electrochemical, Inc. FT-2 Catalyst (stabilizer)	10%
	Concentrated copper sulfate (35 oz.CuSO4/gal)*	10%
	50% (wt.) hydrogen peroxide**	10%
	Generally speaking this bath also works well for bubble assisted etchers, "wave etchers", and some models which employ mechanical agitation of the workpiece.
	* The addition of copper sulfate to the bath is not strictly necessary since it will form as the primary byproduct of etching copper. Be advised, however, that the performance of the bath will be less predictable until the copper sulfate content approaches 6 oz./gal (48 grams/liter) by analysis
	** If 50% hydrogen peroxide is not available, a 35% (wt.) or 19% (wt.) solution can be used. Remember to scale the amount added based on the concentration used (see hydrogen peroxide analysis).
Type	Component	Concentration by volume
S p r a y	deionized (or distilled) water	40%
	35% sulfuric acid (car battery acid)	35%
	MFG 244 Stabilizer	5%
	Concentrated copper sulfate (35 oz.CuSO4/gal)*	10%
	50% (wt.) hydrogen peroxide**	10%
	* The addition of copper sulfate to the bath is not strictly necessary since it will form as the primary byproduct of etching copper. Be advised, however, that the performance of the bath will be less predictable until the copper sulfate content approaches 6 oz./gal (48 grams/liter) by analysis
	** If 50% hydrogen peroxide is not available, a 35% (wt.) or 19% (wt.) solution can be used. Remember to scale the amount added based on the concentration used (see hydrogen peroxide analysis).