Copper is a very elegant ductile metal that was often used in the past to make objects, containers or various dishes. Another use of copper in the home environment is the construction of gutters and profiles around houses. The characteristic and bright color makes it particularly suitable for these embellishment elements.
Copper surfaces are particularly reactive with air and, consequently, tend to change color in a short time. This can be seen in a more drastic way for the copper exposed outside, where it will create a layer of brownish oxide that will hide the natural beauty of the metal. There is not a single type of copper oxidation, in fact, depending on the environmental conditions, more complex oxides or hydroxides can be created, which can give much more different colors. However, it is precisely the presence of these oxides that keep the metal intact over time, so there is no problem in leaving the metal "abandoned" since its functionality will not be affected.
For those who want to try their hand at cleaning copper, they can use different techniques. Some household procedures are very widespread, where the copper object is washed (pans, teapots, vases, etc.) using products easily available in the kitchen. Usually wine vinegar is used, used concentrated or diluted, or mixed with table salt. The salt serves to increase the solubility of the copper ions detached from the acid. However, this procedure is effective in synergy with mechanical action or if oxidation is not too advanced, otherwise it would take too long and several applications. In fact, in the case of external artifacts such as gutters, stronger products must be used, first of all is muriatic acid (or hydrochloric acid), which is found on the market even at rather high percentages. It is a strong acid and consequently attention must be paid, however it is very fast and allows the removal of heavy oxides. In the following photos you can see the effectiveness of a single application of muriatic acid (using a spray or a soaked rag). It is advisable not to work in the sun and to always rinse after application. Subsequent application may be necessary to make the metal gradually brighter.
At the end of the pickling, it would be advisable to treat copper with special products for the conservation of the surface and to slow down future and inevitable reoxidation. Some well-known commercial copper cleaning products already contain brightening and polishing raw materials (such as some silica earth) and complexing materials (such as oleic acid).