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I tried that site URL and it opened for me perfectly. Can't seem to get this site working properly for some reason.  I will try and figure out the problem.

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Hi there, I dont know if I am writing in a proper board but I have got a problem with activation, link i receive in email is not working... http://www.ndiprintmaking.ca/?5481c73746d122d5bfdeacf0cc3,

I think this topic was already mentioned at this forum

I think this topic was discussed loads of time before at this forum

Many thanks Nick.

When salt and sodium bisulfate are mixed, they form hydrochloric acid, the strength depending on how saturated the solution was made. Hydrochloric acid attacks both aluminium and zinc with the production of hydrogen gas in all cases. This flushes the fine copper particles from the etched line, but the actual removal of metal is taking place on an electro-chemical level, depending on the potential voltage difference between the metals on the electrical reaction scale as compared to hydrogen. This is explained on my site at the university of Saskatchewan in the paper co-written by Dr. Bader and me. In the meanwhile, the hydrochloric acid is also dissolving a small amount of the metal to form hydrogen and a chloride of that metal. The two reaction have no bearing on one another, only that they produce metal salts the might get into some final reaction between themselves to form solids that will eventual precipitate. The chemists with PHD's told me that the reactions can be very complicated even though it looks simple at first. I have seen attempts on the Internet to explain the chemical process, but it really doesn't come close to what I was told by our chemistry department.

Since I can't remember the valances for the chemicals, I will just give you an indication of what is happening. Al+CuSO4 = Al(SO4)3+3Cu. While this looks like simple chemical reaction, it is the metals voltage difference that removes the aluminium to give us copper. The hydrochloric acid will attack the aluminium: HCl+Al = AlCl3+3H. Along the way in the bath, the salts will react and might even bring water into the process to produce aluminium hydroxide Al(OH)3, when the bath loses its acidity. In the meantime, there will be cupric chloride and copper chloride, depending on acidity and presence of free oxygen in the solution. If cupric chloride is formed, then the bath will regenerate for use again.

There is no reason to filter out the copper particles as they are necessary to regenerate the mordant more quickly. If there is enough salt in solution, it and bisulfate will dissolve the fine copper into sulfate - but more likely chloride. If left in an open tray, solution tend towards cupric chloride that is very effective in etching metal. I suggest you read about the new method I developed of etching copper with copper sulfate by converting it into cupric chloride. It is on the home page of this blogsite. Also on how to eliminate all toxic chemical from the spent mordant before pouring it down the drain.

By the way, I prefer to call it salt etch as that was the name we gave it at the university when I developed it in 1992.

Hi
about my previous post and to avoid misunderstanding, the point is not to be in doubt at saline etch quality but to explain hydrogen bubles origin when bitting aluminium.

I made an etching with aluminium, it works fine using saline etch.
Nevertheless I've a concern about. A friend of mine, (Gary Thibeau french printing press builder) does not agree with following comments  we can find in litterature about saline etch:
As with zinc, the Saline Sulfate Etch for aluminum produces of a loose coppery sediment which floats to the surface and needs to be removed regularly. Unlike with zinc, a continuous rising of small hydrogen bubbles (not considered a hazard) also indicates that etching is in progress. 
He wrote on my forum(   http://aquatinte.forumactif.com/forum-aquatinte-f1/    ) this is chemically impossible according to the components:
Copper sulfate, Sodium chlorure, water and aluminium.
Who can give here the chemical reaction formula?
Thanks from France to all of you
jean-claude
PS sorry for my bad english...

Hi Merjoguebrell:

What kind of printmaking are you doing and where can we see some images?

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Hi Marshall:

I really don't know why the PineSol system did not work for you this time. Maybe PineSol has changed their formulation for some reason. I have been using the large amount I ended up with when doing the research and have not bought any Pinesol or Palmolive since early 90's.  I am surprised to see you  have lots of foam, which is hard to get from the usual viscosity of the mixture. Try a small amount and add more Palmolive to see if the emulsion holds as that seems to be sort of the problem. I have started to use the mixture to remove the ink off the linear offset blanket, but first getting most of the ink off the blanket by printing on several pieces of paper until no more ink remains, then the solution removes the ink very easy. Sometimes I might spray an industrial degreaser on the blanket before I use a piece of Sham Wow to wash off the residue.

I am sure there are many industrial degreaser than can be made more effective by adding a bit of turps and more surfactant. I chose PineSol as it is common in grocery stores and easy to get. Maybe you added too much Turps to your mixture and eventually the emulsion broke down. Good luck on more tests.

Cheers

Nik