I agree that there will be no difference because of the CO2. The ionics 
in any plating solution will be such that they will 'drown' the CO2, 
probably by 4 or 5 orders of magnitude.

However, I disagree that chlorides are added to tap water for 
disinfection. It is chlorine that is added, not at all the same thing, 
in most places (UV-generated ozone in a few places, especially after 
desalination). Chlorine is non-ionic, although it can react with organic 
impurities and some of the reaction by-products may end up as chloride 
ions. In Europe, much of the tap water has a conductivity of 100-500 
µS-cm, but this is because of dissolved minerals, not the chlorine.

Brian

On 06/04/2011 15:42, Paul Reid wrote:
> You should see no difference in the two ... all things being equal (like
> the same volumes etc.)
>
> Electroplating baths are ionic solutions. They are acid based solutions
> with metal ions. So resistivity of the water used in bath maintenance is
> not so important as what is in the water.
>
> In incoming water may contain contaminants, or even additives, additives
> like chlorine. Chloride concentration will have an effect on things like
> anode corrosion. City water in the fall is laced with chlorides which
> the municipality increases to fight intestinal disease (at least in New
> England). I could maintain chloride levels in the fall without making
> additions in New Hampshire. Plating bath maintenance changes seasonally
> based on the water contaminants, additives and temperature.
>
>
> Many companies use RO and ionic exchange colums to remove the variables
> inherent in "City" water. Treating the incoming water also allows the
> water to warm up to room temperature.
>
> When I was working in a shop outside of Boston (in a city that starts
> with W) the incoming water was not pure enough to be dumped down the
> drain and meet EPA requirements. The city water was clean enough to
> drink but not clean enough to go directly into the sewer without
> treatment.
>
>
> PS. I think I am not able to post to technet again. Might be an email
> issue at our end. If this bounce back from TechNet I'll ask to have it
> fixed.
>
> Paul Reid
>
> Sincerely,
> Paul Reid
>
> Program Coordinator
> PWB Interconnect Solutions Inc.
> 235 Stafford Rd., West, Unit 103
> Nepean, Ontario
> Canada, K2H 9C1
> 613 596 4244 ext. 229
> Skype paul_reid_pwb
> [log in to unmask]<mailto:[log in to unmask]>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls
> Sent: April 6, 2011 8:33 AM
> To: [log in to unmask]
> Subject: Re: [TN] [TechNet] DI water and plating
>
> I am being vague on purpose.
>
> Lets try this.  Lets say I have two scenarios.  In the first scenario,
> DI
> water is generated at about 16 megohm-cm and is fed directly into the
> plating tanks.  Chemically clean and high resistivity.  Second
> situation,
> the DI water goes into a large holding tank (plastic) where the 16
> megohm-cm water becomes 2 megohm-cm water just from sitting around, and
> gets piped into the plating tank.  Still clean chemically, but now has
> lower resistivity from CO2 mixing.  Lets say the tank is silver plating,
>
> just for fun.  Am I going to see any difference in plating between the
> two
> scenarios, all other factors being equal, because one has lower
> resistivity than the other?
>
> Doug Pauls
>
>
>
> Dennis Fritz<[log in to unmask]>
> 04/05/2011 08:08 PM
>
> To
> [log in to unmask], [log in to unmask]
> cc
>
> Subject
> Re: [TechNet] DI water and plating
>
>
>
>
>
>
> Hmm, Doug, I too must ask for some clarification for your question.  All
>
> electroplating baths I know have high concentrations of acids or highly
> conductive salts, to the point that the bath should have essentially
> zero
> resistance.  The voltage registered when electroplating is that used to
> reduce metallic ions to elemental metal, not to drive current through
> the
> bath.  That
>
> This voltage is the basis of the electomotive scale or electromotive
> force.   It is always good to use DI water to make up an electroplating
> bath, because some common anions - like chloride - need to be well
> controlled.  For instance in a sulfate copper electroplating bath,  the
> chloride acts as the "anode corroder" causing the metallic copper
> electrode to be "etched" with a film of cupric chloride and go into
> solution.
>
> Are you thinking about the rinse water after plating?
>
> Denny
>
>
>
> -----Original Message-----
> From: Douglas Pauls<[log in to unmask]>
> To: TechNet<[log in to unmask]>
> Sent: Tue, Apr 5, 2011 12:04 pm
> Subject: [TechNet] DI water and plating
>
> Good morning all.  I have a general question for those of you who deal
> with electroplating.  How critical is the resistivity of the water to
> the
> plating process?  I am not talking about impurities in the water, only
> the
>
> resistivity of it?
>
> Doug Pauls
>
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