Homebrew PCBs

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.
>> 
>> 
>> 
> 
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