Homebrew PCBs

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60vol would be 18%


On 12 Mar 2013, at 23:34, Peter Harrison wrote:

> Actually, Hydrogen Peroxide in strengths of 30% and upwards is potentially very unpleasant and becomes increasingly dangerous if not handled and stored correctly.
> 
> Note, this is 30% by weight. It may also be described as 100vol. That means it will release 100 times its liquid volume of pure oxygen.
> 
> Read this:
> 
> http://www.sciencelab.com/msds.php?msdsId=9924299
> 
> and this:
> 
> http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1246260031375
> 
> and be sure you are completely clear whether the strength of the H2O2 you have is, say, 20vol or 20%.  The stuff used in hair bleach is going to be about 3% which is 10vol. I am reasonably sure that the strongest you are likely to find in a hairdressing wholesaler will be about 20% (60vol). It is sold for dilution by the salon before use. 
> 
> Peter Harrison
> 
> 
> 
> 
> On 12 Mar 2013, at 18:33, Eddie Stassen wrote:
> 
>> Being safety concious is always good, but ffs you are not going to require
>> amputation from a drop of peroxide on your finger.  Whitened skin, some
>> stinging or in extreme cases some blistering perhaps
>> 
>> 
>> On Tue, Mar 12, 2013 at 7:51 PM, smilingcat90254
>> <smilingcat@...>wrote:
>> 
>>> **
>>> 
>>> 
>>> First of all, distilling hydrogen peroxide from pharmacy grade 3% VOLUME
>>> peroxide is relatively easy. I posted it some time ago and some one
>>> recently said it as well. It's by freezing and throwing away the ice that
>>> forms.
>>> 
>>> **** safety ****
>>> You need to be extremely careful in handling this concentrated stuff. You
>>> can only reach about 40 some odd percent concentration by freezing. Still,
>>> its "dangerous". I've accidentally had few droplets hit my finger (Yes I
>>> should have been wearing my chemical gloves but I wasn't) and the skin
>>> where the droplet hit, the skin immediately turned white, chemical burn.
>>> Then the liquid penetrated into the dermis, layer of skin where there are
>>> blood vessels and nerves. And the painful stinging sensation from the
>>> peroxide burn was really intense. It was good that I had the sensation. Had
>>> it stopped, then it would have meant that my finger would have to been
>>> amputated...
>>> 
>>> ****Another safety aspect of handling peroxide****
>>> DO NOT EXPOSE TO UV OR EVEN BLUISH LIGHT (florescent light, sunlight is a
>>> big NO NO).
>>> 
>>> DO NOT LET IT COME IN CONTACT WITH ANY METAL ESPECIALLY IRON BASED
>>> MATERIAL. This includes all stainless steel. Iron act as a catalyst to
>>> decompose peroxide into oxygen and water.
>>> 
>>> Store in clean dark brown bottle but it should not be so airtight
>>> that it can build up pressure. Countless number of explosions have
>>> happened because of this most famous is the accidental sinking of Russian
>>> super sub the Kursk.
>>> 
>>> **** Side note ****
>>> do not confuse volume concentration such as 3% vol H2O2 with 3% H2O2. big
>>> difference. You can not get 90% H2O2 nor can you make it at home unless you
>>> know lot about chemistry and have the right equipment.
>>> 
>>> Concentrating H2O2 by freezing is more than plenty good for your etching
>>> need!! Don't make it any more dangerous than need to be.
>>> 
>>> 
>>> 
>> 
>> 
>> [Non-text portions of this message have been removed]
>> 
>> 
>> 
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>> 
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>> 
> 
> 
> 
> ------------------------------------
> 
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> 

Peter Harrison
peter.harrison@...