Granite discolouring

[hillhead]

Hello folks,
Last week i tiled an outside set of steps in grey brushed granite, bullnosed edging etc.
The customer rang me last night saying that the granite is changing colour and that 3 of them look orange.
I told him that the granite was probably still drying out as it was damp when fitting, i had told him to hang back a few weeks but he needed it done asap for family reason.
My supplier is going to investigate on thursday morning.
Anyone ever see this before?
My supplier says it's unusual but there will be no prob covering replacements etc.

 

[DHTiling]

Is it a full colour change or just small parts of the tile..?

 

[hillhead]

I haven't seen it yet Dave, but from talking on phone i think its on parts just.
Enough to cause him alarm though.
It could be interesting.
I done a great job on his steps too.
Probably chinese granite i think.

 

[DHTiling]

It might be iron mineral within the stone.. rusting due to wetting outside.. worth checking.

It has been known on some cheaper import stuff.

 

[Spud]

rust perhaps ? or tanin from leaves or guano all can cause orange marks on granite

 

[Pebbs]

I just spat my tea out! I have the same problem only this is composite Ceaserstone, installed it two weeks ago and got a phone call today saying theres oranges splodges on some of the skirtings. I dont understand how there can be, the substrate is marine ply which has been tanked. Im hoping its the painters or im stuffed.

Lynn

 

[hillhead]

i found this.....Oxidation : Oxidation, also referred to as "rusting" occurs when oxygen assisted by
moisture combines with iron-bearing minerals. Oxidation is accelerated by
moisture and high temperatures. It is an important process in the alteration
of iron and magnesium rich minerals. Mineralogically iron occurs in three
states...metallic...ferrous (Iron II)...ferric (Iron III). During the oxidation
process Iron II is converted to Iron III resulting in color changes and a
weakening of the mineral structure. Ferrousmagnesian silicate minerals that
undergo oxidation are responsible for the appearance of rust spots on some
granite-type stones. When marble or limestone contains sulfide minerals
such as pyrite, and it undergoes oxidation, the Iron II in this composition will
produce rust spots and the sulfur is converted to sulfuric acid which can
dissolve the calcium producing pitting. Iron oxide minerals are common in
sandstone and over time may develop rust spots.During the oxidation
process an increase in volume of the mineral structure can occur, usually
making it softer and weaker and rendering it more vulnerable to other
elements of the chemical weathering processes.

 

[DHTiling]

Like i said didn't i..:lol:

 

[hillhead]

Weathering

Good reading Lynn.

 

[Rob Z]

Joe, I don't know what's scarier---the problems with your steps or the fact that i can remember this stuff from chemistrty class in college in the mid-80's ? :yikes::yikes:

:smilewinkgrin:Seriously, though....I have had this happen before, and it's darn frustrating. It's good that the supplier is going to give replacement material to you. Hopefully, the new stuff doesn't do the same.

i found this.....Oxidation : Oxidation, also referred to as "rusting" occurs when oxygen assisted by
moisture combines with iron-bearing minerals. Oxidation is accelerated by
moisture and high temperatures. It is an important process in the alteration
of iron and magnesium rich minerals. Mineralogically iron occurs in three
states...metallic...ferrous (Iron II)...ferric (Iron III). During the oxidation
process Iron II is converted to Iron III resulting in color changes and a
weakening of the mineral structure. Ferrousmagnesian silicate minerals that
undergo oxidation are responsible for the appearance of rust spots on some
granite-type stones. When marble or limestone contains sulfide minerals
such as pyrite, and it undergoes oxidation, the Iron II in this composition will
produce rust spots and the sulfur is converted to sulfuric acid which can
dissolve the calcium producing pitting. Iron oxide minerals are common in
sandstone and over time may develop rust spots.During the oxidation
process an increase in volume of the mineral structure can occur, usually
making it softer and weaker and rendering it more vulnerable to other
elements of the chemical weathering processes.