It could be crystallised mineral salts (insoluble salts) which will not come out. or (more likely) the grout color wicking in. This is why you always use white thinnest with limestone and white stones, and could get this with natural gray grout. First thing I would do is to wait a bit longer, maybe put some heat on it, see what happens.
On 12 Sep 2016, at 6:24 am, Justin Cameron <email@example.com> wrote:Got this email some suggestions on cause and a remedyThank youJustin
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Begin forwarded message:From: Haresh Mehta <firstname.lastname@example.org>
Date: September 11, 2016 at 11:26:22 AM PDT
To: Justin Cameron <email@example.com>
Subject: STAINS ON THE FIRPLACEI am sendding you some pictures.
this projecctwas done in mid March. Mason told us that these stains will disappear as it is caused by moisture absobed by stone . we have been waitng for. five months with not much luck. He thinks is caused by alkaline staining.
I wonder if there some way to remove these stains. He is suggesstig paiting the fireplace.
Thanks for your very prompt response
Haresh MehtaVisit list archives, subscribe, unsubscribe or change your subscription preferences: http://stoneandtilepros.simplelists.com/sccpartners Start a new conversation (thread): firstname.lastname@example.org