Metal nail reaction in wall filler

Question

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Please help explain what is happening to this nail. It has been in this wall filler for a good few months.

The substance being excreted was rising up forming these stalagmites, with a liquid forming on them.

Removing the nail, there were also excretions at the part that was sunken.

Sorry there is no chemical composition on the products label. Its used to fill up cracks in the wall... so a type of cement that hardens once applied to a surface. — Andrew, Sep 23 '19 at 06:51
Do you have a name for the product so we can look up its composition? — Buck Thorn, Sep 23 '19 at 06:54
This is the product: http://durapaints.co.za/product/prolong-supafill/ might have to contact the company for chemical breakdown. — Andrew, Sep 23 '19 at 07:15

score 2 · Answer 1 · answered Sep 21 '19 at 16:21

It is such a beautiful picture, perhaps good for a chemistry book cover. It is a similar phenomenon as what happens in a so-called chemical garden. Water seems to be creeping up to the nail head, and helping in oxidation of iron salts to insoluble hydroxides. Finally the gelatinous membranes act like semi-permeable membranc in the osmosis like experiment.

The figure shows several salt crystals soaked in a slightly alkaline medium.

Ref: From Chemical Gardens to Chemobrionics,Chemical Reviews, 2015, 115(16) DOI: 10.1021/acs.chemrev.5b00014

Thanks for the comments - don't know much about chemistry but your answer does sound good. There does still seem to be some unknowns, but I guess that is why it is called a phenomenon. — Andrew, Sep 23 '19 at 06:49

Metal nail reaction in wall filler

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