I do expect a word on this from you Steve.
thanks
ST
On Wed, 12 Apr 2006 10:47:21 +0200, Len Warner <
yahoo@...>
wrote:
> On Tue, 11 Apr 2006 at 23:51:11 +0200, top-poster Ronald Vanschoren
> regurgitated:
>> I just bought this thing:
>> http://www.conrad.fr/webapp/wcs/stores/servlet/ProductDisplay?catalogId=10001&storeId=10001&productId=221211&langId=-2&parent_category_rn=18948
>> Not sure if it is pure NaOH, but I guess so. I says to solve it into 1
>> liter of water and develop for about 1 minute.∗
>> ∗
>> guja wrote:
>>
>> >7-10 g NaOH in 1 liter!
>> >
>> >Ronald Vanschoren <yahoogroups@...> wrote: .....
>> > I developed the PCB in a NaOH solution (1 liter for 35grams NaOH).
>
> Reading this backwards, as required by Ronald...
>
> [ guja deserves part of the blame ;-)
> but at least they trimmed their quotes
> - except the group links :-(( ]
>
> ...Ronald first says that he used 35g/litre NaOH then,
> when challenged to use only 7-10g/litre,
> Ronald admits to using CRC "revelateur en poudre 1442"
> which he 'guesses' is pure NaOH.
>
> But (a) it's not 35g, it's only 30g
> and (b) it's not 'pure NaOH' - it isn't _even_ NaOH' at all !!
>
> It's 100% disodium metasilicate.
>
> Hint: when unsure of a commercial product,
> search for a MSDS (Materials Safety Data Sheet), like
> http://www.crcind.com/wwwcrc/msds/BB4031442-3.htm .
>
> Sodium metasilicate is commonly used in laundry products
> because (AIUI, IANAChemist) it dissociates into a highly
> alkaline solution (pH 12.6 at 1 % concentration) but, unlike
> NaOH, it does not decay in storage by absorbtion of
> atmospheric carbon dioxide.
>
> So 35g/litre NaOH is a different animal from 30g/litre
> "revelateur en poudre", with a much bigger bite.
>
> But what would you expect from a top-poster :-P
>
> Sorry, Ronald, only joking - anyway, we'll be rid of you
> after you self-medicate with a proprietary cold remedy
> _and_ paracetamol tablets ;-) The chemistry does matter!
>
>
> Regards, LenW