We often stress the importance of using and storing Multi-Etch in plastic containers, never in metal or glass. First time users will receive dry Multi-Etch powder in a plastic gallon jug. This jug is meant to have distilled or deionized water added to make a gallon of regular strength or 1/2 gallon of double strength Multi-Etch. You can pour 150–160°F water into the jug to mix the solution.
When using heated Multi-Etch in either a double boiler or in a custom tank, there are a number of types of plastics that can be used. For small users (one gallon or less,) you can find suitable plastic containers at big box or grocery stores. Look on the bottom of containers to see a number inside a triangle. Most of these containers will have a number 5, for polypropylene. These can withstand up to at least 212°F.
For those of you building your own containers, several other plastics besides #5 can be used:
#2 white polyethylene can be heated to 160°F. This is what our Multi-Etch jugs are made of.
#3 PVC--upper thermal limits are 140°F for type 1 and 158°F for type 2
#7 is usually polycarbonate and can be heated to 212°F but #7 does include other plastics so sometimes means a type other than polycarbonate.
If you will run larger tanks of 5-20 gallons, we recommend IPEC Global who can construct complete customized systems which can include tanks for cleaning, rinsing, Multi-Etching, rinsing, and anodizing.