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How Stain Resistant is
Granite?
(by Steve Walker)
I have been a stone and marble mason for
forty years and for all of my working life I have been obsessive
about keeping potential stain creating products out of my workshop
and away from my stocks of stone , marble and granites. It
therefore follows that my experience of stain damaged materials
have been limited to rare accidents over the years. And most of
these have involved marble, in fact I have been unable to recall a
single occasion when we had an example of granite
staining.
With the increasing use
of granite for
kitchen worktops and my current speciality
house signs, I have recently had cause to consider just how stain
resistant is natural granite? To try to answer this question I set
up a small experiment to try to deliberately introduce stain damage
to a piece of granite using products found in the average kitchen.
The Experiment: I used a piece of
Nero Impala granite 20mm thick with a highly polished face. Nero
Impala is a tight grained, mid to dark grey mottled granite from
South Africa. I chose this type of granite as being a typical
mid-range granite in terms of hardness and colour. This piece has a
normal polished finish and has never been sealed to prevent
staining.
I lay the piece of granite
on a horizontal surface indoors and left it to thoroughly dry out
for a couple of days.
I stuck a number of small
labels across the face of the granite and next to each label
introduced one of the chosen staining agents and as I introduced
each new product, wrote he name of the product on the adjacent
label in pencil. (Tip: if you are labelling
something in conditions where the labels may get wet, use
pencil.)
I then left the granite and
the staining agents to do their worst for a full eighteen
hours.
The Staining Agents: (and my expectations of
them) 1. Vegetable Oil: Oils have
always been taboo around marble workshops and are guaranteed to
stain marble. I was certain these oils would leave at least a wet
looking stain on the granite. 2. Same as vegetable oil really but
different oils do have different characteristics and olive oil is
common to most kitchens. 3. Soy Sauce: I thought the combination of
the dark colouring and the potentially corrosive nature of the
vinegar base would be a serious contender to cause damage 4.
Vinegar: I expected the vinegar to act as a corrosive and at least
slightly degrade the polish. 5. Beetroot Juice: Beetroot juice is
one of the most deadly stains I know of, as any housewife knows and
I was pretty sure that this would soak in and leave a nasty purple
stain. 6. Ketchup: Contains oil and vinegar and a lot of colouring
is superb at staining kids clothes! 7. Tea Bag Wet: Tannin is a
strong staining agent I expected this to leave at least a surface
stain and an underlying water mark. 8. Washing up Liquid: Soap will
stain marble so definitely worth a try. 9.Scotch Whisky: Don’t
panic! I used the cheap cooking stuff. I really was confidant that
this would degrade the polish. On marble any strong alcohol spirit
will cut through the surface polish so I assumed the same would be
true of granite. 10. Red Wine: We all know how pervasive red wine
stains can be. And any excuse seems good to open a new bottle!
11.Lemonade: You may be suprised to know that lemonade will also
destroy the polish on marble if left for long enough, over eighteen
hours I was pretty sure it would do some damage to the granite. 12.
White wine: Ok I didn’t think this would do any harm but it was
open anyway! 13. Tabasco Sauce: Hey! this stuff burns throats like
anything so why not granite ? 14. Lemon Juice: Very acidic of
course, and if the lemonade does the trick neat lemon juice should
work even better ( or worse depending on your viewpoint!). 15. Half
an Orange: Citric acid and orange colourant, should be
interesting.
Ok that’s the lot, I was
pretty confidant that the oil, the beetroot and the whisky would
cause some damage but I was not sure about the others.
After the eighteen hours I
mopped up the residue of the various staining agents and cleaned
the surface of the granite with a normal kitchen spray cleaner and
left it to dry for ten minutes.
I then inspected the
granite in daylight for damage to the polish from corrosive acids
and staining from the colourants and the oil based
products.
The Result: Nothing! No
staining no degrading of the polish not even the wet looking stains
I was sure would be caused by the oils and the wet agents. This was
a real surprise, eighteen hours is a long time and under normal
domestic conditions any spillage would be cleaned up much sooner.
This is a really impressive result for the granite but a bit of a
blow for me as I had hoped to write further articles on removing
stains and re-polishing alcohol spots!
Still I mustn’t be too
surly about it, I have always been an admirer of the qualities of granite but now I can quote the stain resistant virtues of the
stuff with great confidence.
One caveat however, there
are many different
types of granite and I cannot guarantee that
this performance will be as impressive with them all, or that I
have tried every potential staining or corrosive product, but I
have no reason to think that other granites are more susceptible to
damage or that any other agents pose a bigger threat. | 