I am recently getting into PCB etching. So I use 10 M HCL solution, 3% hydrogen peroxide mixed in 1:1 ratio for my etchent. Currently, I am storing my HCL and hydrogen peroxide in my shed which can vary in temperature from -10 degrees Celsius to 25 degrees Celsius. The shed is outside my house. I also store my etchent next to HCL and hydrogen peroxide in the shed as well. Will it be safe to store all of these three chemicals inside a shed?

I do have metal tools in there but I don't care if it rusts. I am just afraid of hydrogen gas that might form because of HCL fumes. Also, I store my acetone indoor inside a plastic container because I heard that its flash point is -20 degrees Celsius. I don't want it to spontaneously catch on fire if I did store it in the shed. So are these storing method adequate or do I need more precautions.

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    $\begingroup$ You probably have gasoline in the shed which is about as dangerous as acetone. 3% hydrogen peroxide can be bought in a drug store, so no biggie. The 10M acid is a problem to me. It probably is in a glass bottle. What if you knock something over in the shed which breaks the bottle? Since you're asking the question I seriously doubt you're taking the proper safety precautions. Also kids then to play around in sheds. So the shed needs to be locked at least. $\endgroup$
    – MaxW
    Oct 15, 2016 at 0:56
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    $\begingroup$ PPE and ventilation are a must. Your info on acetone is way off - mine regularly withstands 40 Celsius (or higher). You'll get more expert advice that what I can offer here, but do be careful. Also: my glassware and all chemicals (including things like bug spray and the like) are in double-locked, explosion-proof cabinets. $\endgroup$ Oct 15, 2016 at 0:57
  • $\begingroup$ I dont have gasoline in my shed and no one even comes in here anyway. The 10M acid is in a polyethylene jug not a glass bottle. Also the info about acetone's flash point is from MSDS. $\endgroup$
    – steven
    Oct 15, 2016 at 1:39
  • $\begingroup$ Not a danger, but household 3% hydrogen peroxide slowly decomposes, and decomposes more rapidly when mixed with almost anything (phosphates being one exception). The peroxide's shelf life is limited, particularly once opened, or mixed with HCl, or with large temperature swings. Unless it takes up too much room, I'd store it in my house. $\endgroup$ Oct 16, 2016 at 2:44

2 Answers 2


You don't need to take any special precautions when storing these chemicals together compared to how you would store them individually. They should all preferably be stored in their original, properly labeled containers with properly fitting lids.

Regarding your concern for hydrogen gas forming from the HCl fumes, that is simply not a reaction that will take place from only the compounds you've listed, or in combination with anything else you would typically find in a utility or storage shed. You will want to avoid breathing HCl fumes while working with it of course, but as far as a storage concern even this will not be an issue for you.

I commend your extreme caution here in general, although your fears of the acetone igniting from sitting in a hot shed are unwarranted. The flash point of a compound is the lowest temperature at which it can be ignited with an ignition source, like a spark. This is commonly confused with the autoignition temperature, which is the lowest temperature at which a compound can spontaneously combust without an ignition source. So, while you really don't want your acetone near a flame or spark source at any temperature, it's autoignition temperature is $\pu{465^oC}$ and so you don't have to worry about it igniting just from sitting in a hot shed.


I do recall researching on what can cause storage bottles to fail with age, and my recollection included the obvious (like the chemical nature of what is being stored, heating as your shed is likely not air-conditioned and the action of direct or diffused sunlight) together with other things I would not have expected.

For example, a polymer may be effected from the build-up of electrostatic discharge on parts of the surface area of the container (the top, for example) from dust (dirt) particles driven by wind drafts. A source notes:

Most plastic materials are electrical insulators and have the ability to support high static build up. Static is produced by charge separation caused by the movement of one material over another. Static build up can result in issues including:

•Increased handling and contamination issues during transport, storage and packing

With respect to contamination, see 'Effect of Electrostatic Charge on the Contamination of Plastic Food Containers by Airborne Bacterial Spores'. So, upon opening, charged dust particle contaminants could enter a vessel, leading to a possible decomposition reaction.

A possible chemically more direct effect of electrostatic forces per this source, to quote:

formation of polyelectrolyte complexes through electrostatic interactions between the protonated amino groups of chitosan and the negatively charged side-chain groups in the other biopolymer at the operating pH [26,29].

This source cites some new unexpected causes of failure of polymers with aging, to quote:

However, non-biodegradable polymers can be degraded/fragmented by various mechanisms: physical, such as heat and light, and chemical, such as oxidation, ionic radiation, and hydrolysis. Certain air pollutants such as CO, sulphur dioxide (SO2), nitrous oxide (NO) and ozone (O3) can also play a major role in the degradation of polymers [71]. The effect of the aforementioned degradation mechanisms to the polymer is to embrittle and fragment it into smaller pieces.

So ostensibly, storing in an outside shed may also, unexpectedly, introduce a role for air pollutants, as well, attacking the outside of the container. This may result in embrittlement, which together with physical moving of the vessel, could eventually cause leakage (even if you were storing something inert!).

Now, from higher temperature exposure along with a possible contamination of metal oxide riched charged dust particles entering the H2O2, I would expect a reduced life span with some oxygen evolution.

More interesting is there any expected impact on the HCl? If the hydrochloric acid is muriatic, already an Fe presence. Adding more metal ions from dust, I would expect only a minor loss in the acid strength, with limited to no gas creation. However, a possible increased attack of the container from within, proceeding via a REDOX reaction forming radicals, but only if there is a good amount of air available in the container along with a transition metal(s) ions and especially light. Here is a source on the alluded to transition metal/oxygen based REDOX:

Transition metals are efficient catalysts of redox reactions and their reactions with dioxygen are not spin restricted. Therefore it is likely that the "autoxidation" observed for many biomolecules is, in fact, metal catalyzed. In this paper we discuss: 1) the quantum mechanic, thermodynamic, and kinetic aspects of the reactions of dioxygen with biomolecules; 2) the involvement of transition metals in biomolecule oxidation; and 3) the biological implications of metal catalyzed oxidations. We hypothesize that true autoxidation of biomolecules does not occur in biological systems, instead the "autoxidation" of biomolecules is the result of transition metals bound by the biomolecules.

Related comment on acetone with no presence of dioxygen, likely no chemistry-based issues. Otherwise, still not too likely that one will see breakdown products (including gases, like CxHy). However on opening, one has a mixture of acetone and air, together with any possible ESD, is not a completely safe scenario.


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