Interpreting lemon test

Hi, I'm considering installing a serizzo monterosa countertop. I did the lemon test on a sample of the stone and am not sure how to interpret the result. Serizzo monterosa is white with black swirls and has a bit of silver flecks. The part of the stone in contact with the juice did "darken", but it did not develop "dark spots." I couldn't tell if the "darkening" was just how the stone looks because it's wet. Is the test considered failed if dark spots appear where there were none before? Or is it failed if the stone darkens. After wiping with a dry paper towel, the stone was still slightly darker, but by morning it looked like it did originally. The slab we are considering buying has some yellow/rust colored spots. The fabricator is telling us that serizzo monterosa has a lot of iron ore, and so some spots are natural to the stone, but we shouldn't expect a significant number of new spots to appear if we cut the countertop from the parts that are spot free. Should we be worried about additional rust spots appearing in the stone? Thanks! Elsie

 

Dear Elsie:

Seri z z o Monterosa is a variety of an Italian stone (Orthogneiss) coming from the North West of Italy known under the name of Seri z z o Antigorio. Its absorbency rate is 0.35% to 0.4%.

The result of the lemon juice test is telling you that your stone needs to be sealed with a good-quality stone impregnator like MB-4. Other than that, all it's peachy!...

To answer your final question, I wouldn't worry about it. While what your fabricator told you is true, the oxidation of stones containing iron mineral traces can only happens if you have migration of moisture from the bottom of the stone through it core (osmosis); hardly the case with a countertop. Just in case, if you have part of it over a dishwasher, make sure that the bottom of the slab is insulated from the steam with a sheet of plastic or something else suitable.

Now remember, it's never too early to think about the proper maintenance of your stone. The issue of what you'll be doing day in and day out to your stone is far more important than its sealing (if and when possible and/or advisable) and it's all too often neglected. As you can tell by reading many of this site's postings, you're not likely to get good information about it from your dealer or installer. Don't become another statistic! By logging into the Helpful Hints section of our website at: http://www.marblecleaning.org/helpful-hints.htm , you will be able to get the short version of our maintenance guidelines at no charge. The full version of it – a 7-page document considered by many as an industry benchmark – is available in pay-per-download format in our Educational Literature section at: http://www.marblecleaning.org/literature.htm .  

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Ciao and good luck,

Mauri z io Bertoli

 

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