Homebrew PCBs

My etchant is two parts by volume of 3% H2O2 and 1 part 35% "muriatic"
(hydrochloric) acid. The peroxide is just the drug store/supermarket stuff.
The acid is from Home Depot. It's sold for concrete cleaning/prep.

This etchant works pretty fast and I don't think I'd ever need stronger
peroxide.

The 3% I buy is about $1.50 a quart. The acid's about $10 a gallon.

73,

Todd
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K7TFC / Medford, Oregon, USA / CN82ni / UTC-8
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QRP (CW & SSB) / EmComm / SOTA / Homebrew / Design


On Tue, Mar 12, 2013 at 4:49 PM, Peter Harrison <peter.harrison@...
> wrote:

> **
>
>
> Oops!
>
> 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]
> >>
> >>
> >>
> >> ------------------------------------
> >>
> >> Be sure to visit the group home and check for new Links, Files, and
> Photos:
> >> http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >>
> >>
> >>
> >
> >
> >
> > ------------------------------------
> >
> > Be sure to visit the group home and check for new Links, Files, and
> Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
>
> Peter Harrison
> peter.harrison@...
>
>  
>


[Non-text portions of this message have been removed]