Good morning Guy! I have muriatic acid in gallon jigs purchased for acid etching a cement floor prior to coating with epoxy based paint. It was readilyMessage 1 of 2 , Jan 15, 2011View Source
Good morning Guy!
I have muriatic acid in gallon jigs purchased for acid etching a cement floor prior to coating with epoxy based paint. It was readily available at a floor covering distributor. A prior use of HCI was performed during a Mirror Making Event in Delaware years ago using a quart bottle of the acid purchased at a local Home Depot. In Fact it was you who calculated and cut the Couter mask used to test the mirror at that event! I still have it!
If you recall what year that was please tell me as I've forgotten.
Obtaining a small bottle of Ferric Chloride PCB board etchant solution from Radio Shack was a problem. Few if any stores carry it in stock any more. Attempts to have it shipped were complicated. They will NOT ship it to your home; only to stores. I don't remember why but suspect it has to do with HazMat regulations.
I've had similar problems obtaining the chemistry used to coat mirrors with silver. I had to drive from my home in Western New Jersey to the dealer in Manhattan and pick it up personally.
Given the performance similarities of Muriatic acid, the low cost and the ease with which it can be found, I am inclined to stay with that.
Thanks for the tip on accelerating the etching chemistry with copper (II) sulfate crystals. The time needed to strip large mirrors can be frustrating at times. The tip on using paper towels to save chemistry is also appreciated.
I wish all of this worked with gold coatings. I've an 6.25" antique plate glass mirror from a scope built in the the early 20's that was re-coated with gold. I've tried everything but the most dangerous of acids without success. Since the mirror needs to be refigured anyway, I will strip the gold with pitch and cerium oxide. Since it's an f-10, I think I can figure it well given my limited mirror makling experience.
Regards and thanks again.
--- In email@example.com, Guy Brandenburg <gfbrandenburg@...> wrote:
> When using muriatic acid (HCl, swimming-pool strength) to strip an aluminum
> mirror coating, the speed of the operation is increased by an order of
> magnitude or so if you dissolve some copper (II) sulfate crystals in the acid
> first. The exact amounts are not critical. The mixture turns green.
> Putting some paper towels on the mirror and then drenching them with this stuff
> is an economical way of saving solution material.
> Ferric Chloride PCB board etchant solution from Radio Shack works about at the
> same speed.
> I find that using either method, some spots take a little longer. I also find
> that after a few minutes I need to re-jigger where the wet paper towels make
> contact with the mirror.
> Guy Brandenburg, Washington, DC
> My blog, mostly on Education in DC:
> My home page on astronomy, mathematics, education:
> or else