Phosphoric acid
We compared the effectiveness of Ecotec® cream to that of a popular jellied rust remover, which is basically thickened phosphoric acid (which, by the way, is classified as a poison under the Federal Caustic Poison Act). We used the cream form of Ecotec® in order to get as fair a test as possible against the other product. Rusty sheet-metal test panels were cleaned of dirt, dried, and weighed on an analytical balance. One panel was coated with Ecotec®. Another was coated with the phosphoric-acid product. The panels were allowed to hang vertically in air for one hour. After washing in water and drying, the panels were again weighed. The loss in weight of the panels corresponds to the rust removed from them. For Ecotec®, the panel's weight loss was 2.33%; for the other product, the panel's weight loss was 1.96%. In this test, Ecotec® removed more rust than did the phosphoric acid product. Repeats of this test gave the same results.
Hydrochloric (Muriatic) Acid
In addition to phosphoric acid, another chemical that is used to remove rust is hydrochloric acid, sometimes called muriatic acid. We obtained a commercial sample, supplied as a concentrate containing 20% hydrochloric acid. We diluted the concentrate with water according to label directions and immersed seven rusty test panels in it, and another seven in Ecotec® liquid, for two hours. At the end of the test, all seven of the panels soaked in Ecotec® were clean and free of rust. All seven of the panels soaked in the hydrochloric acid solution remained rusty, with only about half the rust removed.
When we tested the commercial hydrochloric acid rust remover concentrate without diluting it, it removed rust very well. However, the pungent fumes liberated when handling the concentrated acid are very irritating to breathe. In fact hydrochloric acid liquid and vapor are highly toxic and corrosive, and can cause severe burns to all body tissue. Inhalation can cause lung damage; if swallowed, it can be fatal. Hydrochloric acid is listed as a poison under the Federal Caustic Poison Act. If diluted with enough water to make it relatively safe to handle, it does not remove rust very well; if used in concentrated form, it is dangerous. Furthermore, to dispose of the used hydrochloric acid lawfully, one must take into account local, state, and federal regulations pertaining to hazardous waste.
Oxalic Acid
Another chemical used to remove rust is oxalic acid. Oxalic acid is both corrosive and toxic. Our tests show it to be relatively ineffective in removing rust.
The above data are based on tests and experience which Singerman Laboratories believes reliable, and are supplied for informational purposes only. Singerman Laboratories disclaims any liability for damage or injury which results from the use of the above data and nothing contained therein shall constitute a guarantee, warranty or representation by Singerman Laboratories with respect to the data, the products described or their use for any specific purpose.
