Steve, Ken, et al,
Thanks for all the cautionary information. I will pass along to the
architect who was going to have a test of Klenztone on the limestone
trim of a 1920s train depot believing it to be a non-acidic cleaner.
Apparently the architect and owner are not happy with the results of a
ProSoCo product (I'll find out what was tried). The guy cleaning the
terazzzo floors said he could take care of the stone as well as the
floors using Klenztone.
The very thin MSDS for Klenztone says that it contains "Ammonium
Biflouride Solution - stabilized" but no information regarding ph. Is
ABF an acid? Iis "ammonium biflouride" different from "ammonium
bifloride" ? The MSDS also says that the product is incompatible with
strong bases and strong acids and "a strong acid will liberate
hydrofloric acid and a strong base will liberate ammonia."
Klenztone literature showed the Lincoln Memorial steps being cleaned..
Are the steps also marble?
Thanks
Mitch
"S. Stokowski" wrote:
> Mitch, Ken, Leland:
>
> In my opinion, hydrofluoric acid is probably the most serious chemical
> hazard in restoration and renovation. It's danger isn't as an acid.
> In fact, it's acidity is so weak that it is fairly ineffective. But,
> this chemical can easily cause severe illness, loss of limbs, and
> death. How? The HF starves human cells of essential calcium. It can
> kill it's way to the bone in your arm or your leg, where it usually
> stops, causing one to lose a limb but not a life. Or, if you splash
> it on your chest, it can just drill to your heart, whereupon the heart
> muscle dies just before the mind.
>
> Why do I know all this about HF? I've been trained in it's hazards.
> I've used it for whole-rock chemical analyses and for separating
> pollen from clay and silt. I've instructed my chemist employees how
> to use HF safely and responsibly. I've worked for a company (Vulcan
> Materials) that made hydrofluoric acid. In my opinion, HF should only
> be used in a fume hood with rubber gloves, a chemical apron, and
> goggles. Why anybody without a wish to die a horrible death would use
> HF in the open air without wearing a full set of protective equipment
> is a mystery. Maybe they are damned fools; maybe they are the low
> bidder. Maybe the boss just figures that laborers are expendable.
>
> I hope that everybody who has or intends to work with HF has calcium
> gluconate gel and syringes in their medical kit. These are essential
> to counteract the effects of HF exposure. I bet that nobody does.
> Perhaps I shouldn't be so cynical.
>
> On the plus side of HF, it works fairly well to dissolve iron stains
> and dust deposits consisting of quartz silt and fly ash. It also
> brightens granites and other quartzose rocks. It dissolves the quartz
> and silicate minerals preferentially at the surface fractures that
> make a stone lighter than it's intrinsic color. If the rock contains
> calcite (calcium carbonate) it reacts to form fluorite (calcium
> fluoride). This precipitated mineral slightly protects the surface.
>
> FYI, the Lincoln Memorial is made of Yule marble from Colorado.
>
> Steve Stokowski
> Stone Products Consultants
> Building Products Microscopy
> 10 Clark St., Ste. A
> Ashland, Mass. 01721-2145
> 508-881-6364 (ph. & fax)
> http://members.aol.com/crushstone/petro.htm
>
> ****************************************
>
> In a message dated 5/8/03 5:24:01 PM Eastern Daylight Time,
> [log in to unmask] writes:
>
>
>> Are any of you stone guys familar with Klenztone cleaning chemicals?
>>
>> One of there products uses a special formula of floride salts.
>>
>>
>> Mitch,
>>
>> I'm quite familiar with the materials and have used them to good
>> effect but am a bit peeved about their lack of truth in advertising.
>> Despite the fact that the advertising states that the chemicals
>> contain no acids the flouride salts turn to hydroflouric acid when
>> they encounter water. According to my materials handbook
>> hydroflouric acid is used in cleaning cast iron castings by
>> dissolving the sand from the castings. What this means for sandstone
>> I think should be self evident. What it means to the Lincoln
>> Memorial, I assume of granite, is possibly less shocking. I would
>> certainly NOT use it on limestone or marble. What gets me with
>> suppliers of chemical cleaning solutions is that they will say that
>> their materials were used in this place, or that, but they will not
>> tell you the truth of the long term results, or what is really
>> needed to know in order to do no harm. I feel that Klenztone is the
>> worse of any in this regard. In the past I've asked Klenztone
>> (directly asked of Klenztone and NOT of any of their suppliers who
>> usually have no idea what they are selling) to give us names of
>> buildings where their products were used in order to revisit the
>> locations in order to determine if the masonry was acid burned, or
>> not. It is when manufacturers are not up front with their
>> information that I begin to suspect ALL of their marketing hype. The
>> "no acids" caveat is one that will catch out preservationists
>> seeking a non-acidic cleaning methodology... well, when you use
>> their product it does look good. It has to be used with the same
>> care, skill and attention as would be used when cleaning masonry
>> with any acidic cleaner. But if your chemistry and science in the
>> beginning exluded the use of acids, then I think it a really lousy
>> deception to pretend that acids are not being used with Klenztone.
>>
>> My first phone conversatin with Martin Weaver was to ask him about
>> Klenztone, and my naive remark that the material contained no acids
>> and I wanted to know how it could possibly clean masonry. His
>> comment, in brief, was that he did not know of any masonry cleaners
>> that would not contain acids. I went away imagining that he would
>> think I was a complete dolt. Some time later I spent an afternoon
>> drinking ale with him and Bobby Watt in a dive in Ottawa and found
>> out Martin is a very very nice guy, a bit hilarious in humor and an
>> out-of-the-box free range nut case.
>>
>> ][<en
>
>
>
--
F. Mitchener Wilds, Senior Restoration Specialist
Restoration Branch
State Historic Preservation Office
919/733-6547
http://www.hpo.dcr.state.nc.us
***My opinions may not be those of my agency.***
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