Marc,
I spent years in the museum environment succesfully advocating for
metals storage and exhibition cases that were NOT constructed out of
wood.
Also I think that in any experiment that you need to reduce the
variables to a minimum and also strive to make sure that the
preparation of all samples is as identical as you can get - for metals
that means polishing, complete chemical degreasing (no residues!), and
no handling with bare hands or used gloves, and when the coupon or the
replicant object is ready it goes right into the container and does
not sit out in the air. You need to be very diligent and thorough.
How clean is clean? A senior scientist at the Smithsonian once told me
that she would have her interns clean the labware - she would then
analyze it with her XRF and if any trace chemicals appeared they would
clean the labware again, and again.
Cheers!
Dave
David Harvey
Conservator
Los Angeles, CA
On 10/2/07, Marc A Williams <[log in to unmask]> wrote:
> But, the wood products are in all built environments, as well as many
> cupboards and display cases. Wouldn't it be a more real-world test? Of
> course, I will defer to you as the metals expert!
>
> Marc
>
> American Conservation Consortium, Ltd.
> 4 Rockville Road
> Broad Brook, CT 06016
> www.conservator.com
> 860-386-6058
>
> *Collections Preservation Consultation
> *Conservation Assessments & Surveys
> *Environmental Monitoring & Low-Tech Control
> *Moisture Management Solutions
> *Collections in Historic Structures
> *Collections Care Grant Preparation
> *Conservation Treatment of:
> Furniture
> Painted Wood
> Horse-Drawn Vehicles
> Architectural Interiors
>
> Marc A. Williams, President
> MS in Art Conservation, Winterthur Museum Program
> Former Chief Wooden Object Conservator, Smithsonian Institution
> Fellow, American Institute for Conservation (AIC)
>
>
> ----- Original Message -----
> From: "David Harvey" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, October 02, 2007 1:47 PM
> Subject: Re: [MUSEUM-L] Need help tarnishing silver
>
>
> > Marc,
> >
> > I would lean away from using plywood or wood products in association
> > with this. The tarnish and corrosion of metals by the organic acids in
> > woods is a different mechanism from sulphide corrosion and thus might
> > produce different results than an experiment using a box/container of
> > an inert material with sulphur. The various silver cloths are
> > speciifcally developed to reduce sulphide corrosion and thus may not
> > work as effectively with the acids outgassed by woods.
> >
> > Cheers!
> > Dave
> >
> > David Harvey
> > Conservator
> > Los Angeles, CA
> >
> > On 10/2/07, Marc A Williams <[log in to unmask]> wrote:
> >>
> >>
> >> How interesting how one thread leads into another! The following link is
> >> about how to clean up spilled mercury, a question from a week ago or so.
> >> It
> >> also states that powdered sulphur can be used to assist in this process
> >> and
> >> that it is available from garden supply houses or pharmacies.
> >> http://www.des.state.nh.us/factsheets/hw/hw-15.htm
> >>
> >> http://www.somaluna.com/product.asp?p=180 Link for
> >> purchase of powdered sulphur - many others available in Google search.
> >> Small town or large city, everything is available over the internet.
> >>
> >> If you want to accelerate the experiment, I would suggest that you heat
> >> it
> >> up. Place the items in a small oven (such as the inexpensive tabletop
> >> ones
> >> - NOT microwave). I wouldn't use a stove oven, as the time period could
> >> be
> >> fairly long, and the energy costs would be high. You can also create
> >> your
> >> own by making a small box (I would use plywood) and placing an
> >> incandescent
> >> light bulb inside. You probably can use the cooler box for your oven if
> >> it
> >> is not flammable. You can change the wattage of the bulb to get the
> >> desired
> >> temperature. Be sure that the bulb does not directly contact anything
> >> flammable. It shouldn't get hot enough to ignite the wood if you stay
> >> below
> >> 100 watts, but check this out carefully if you have wood contact.
> >> Whether
> >> you make your own oven or use a countertop one, insert a digital
> >> thermometer
> >> into the oven - one of those with a long corded sensor for
> >> outdoor temperatures (keep the thermometer body outside the oven) - they
> >> are
> >> about $8 at Home Depot, Wal-Mart or the like. Put the sensor near the
> >> silver samples. I would suggest holding the temperature at 125-150
> >> degrees
> >> F. Higher will move things along faster, but may also cause chemical
> >> reactions to occur that would not at lower temperatures, thereby reducing
> >> the validity of the experiment. Place the items as high in the oven as
> >> possible - the floor of the oven can be considerably cooler than the top.
> >>
> >> I would suggest adding a few silver samples to your experiment. I would
> >> wrap one silver sample is a clean, freshly washed cotton cloth (use a
> >> detergent without perfumes or additives), as the reduced air circulation
> >> of
> >> cloth alone may have an effect. I would place another silver sample in a
> >> polyethylene Ziploc bag, freezer weight, nothing special, just from the
> >> grocery or discount store. These are often recommended as an easy,
> >> inexpensive way to protect items in storage. You probably should have
> >> another sample as a control that is not inside the container with the
> >> others. This could be in a Ziploc bag in the freezer to inhibit any
> >> tarnishing. You may actually have tarnishing on your control in the
> >> cooler,
> >> but it just doesn't show since it is even and slight. This will give you
> >> something to compare it to. If you add these additional samples, you
> >> will
> >> need to polish all the samples again so that you start with the same
> >> amount
> >> of time. Then, place them in their respective protective wraps.
> >>
> >> Cutting up the rubber bands would increase their surface area. The
> >> smaller
> >> the pieces, the better (I wonder what would happen if you put them in a
> >> blender? If you try it, just do a single one in case it causes a
> >> problem,
> >> you can stop immediately without damage to the blender - I'd use the
> >> pulse
> >> button.). You can also use powdered rubber eraser, which can be
> >> purchased
> >> already powdered or you can chop it up yourself (be sure it is actually
> >> rubber, not plastic). Powdered sulphur also may work - no reason you
> >> can't
> >> use both. You may get some odors from the oven, so enjoy them, or do
> >> this
> >> where the smell is not a problem. You can also consider wood sawdust or
> >> shavings, especially oak. Hand planing an oak lumber scrap will easily
> >> produce shavings.
> >>
> >> Just out of curiosity, did the polish you used have a tarnish inhibitor
> >> in
> >> it? That might explain why nothing has happened yet.
> >>
> >> Please report back on this, as I'm sure many of us would like to know
> >> your
> >> results.
> >>
> >> Marc
> >>
> >> American Conservation Consortium, Ltd.
> >> 4 Rockville Road
> >> Broad Brook, CT 06016
> >> www.conservator.com
> >> 860-386-6058
> >>
> >> *Collections Preservation Consultation
> >> *Conservation Assessments & Surveys
> >> *Environmental Monitoring & Low-Tech Control
> >> *Moisture Management Solutions
> >> *Collections in Historic Structures
> >> *Collections Care Grant Preparation
> >> *Conservation Treatment of:
> >> Furniture
> >> Painted Wood
> >> Horse-Drawn Vehicles
> >> Architectural Interiors
> >>
> >> Marc A. Williams, President
> >> MS in Art Conservation, Winterthur Museum Program
> >> Former Chief Wooden Object Conservator, Smithsonian Institution
> >> Fellow, American Institute for Conservation (AIC)
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: Melissa Thompson
> >> To: [log in to unmask]
> >>
> >> Sent: Tuesday, October 02, 2007 9:28 AM
> >> Subject: Re: [MUSEUM-L] Need help tarnishing silver
> >>
> >>
> >> We are not using the cooler to actually cool the silver, just as an
> >> enclosed
> >> environment. I guess we could have used a tupperware tub too, but the
> >> cooler
> >> was more accessible. We are in a small town (pop. 8000) and do not have
> >> access to much. I don't know how we would go about acquiring powdered
> >> sulpher. Would cut up rubber band work for the shredded rubber?
> >>
> >> Melissa Thompson
> >>
> >>
> >> On 10/1/07, Marc A Williams <[log in to unmask]> wrote:
> >> >
> >> >
> >> > First of all, use a wooden box, perhaps fresh plywood, if you are using
> >> > a
> >> box. Why the cooler? This will really slow down the processes. Sulphur
> >> is
> >> available as an element in powdered form. However, it may not volatize
> >> quickly. Shredded rubber may be a better solution. The finer the
> >> particulation, the greater the surface area, and the more quickly it can
> >> get
> >> into the air. Heating any of these will speed the process (even a light
> >> bulb will do), but I'm unclear if the cooler will negate the effect. If
> >> this is a preservation experiment, it would be better to do it at
> >> elevated
> >> temperature, rather than lowered. Any effects can be translated to lower
> >> temperature, subject to the rule of thumb that processes slow in half for
> >> every 10 degree C (18 degree F) temperature drop. Thus,
> >> oxidation/corrosion
> >> at 35 degrees F will be roughly 32 times slower than at 125 degrees F
> >> (or,
> >> at 125 degrees F, they will be 32 times faster than at 35 F). This may
> >> be
> >> your experimental design problem. Please give us a bit more information.
> >> >
> >> > Marc
> >> >
> >> > American Conservation Consortium, Ltd.
> >> > 4 Rockville Road
> >> > Broad Brook, CT 06016
> >> > www.conservator.com
> >> > 860-386-6058
> >> >
> >> > *Collections Preservation Consultation
> >> > *Conservation Assessments & Surveys
> >> > *Environmental Monitoring & Low-Tech Control
> >> > *Moisture Management Solutions
> >> > *Collections in Historic Structures
> >> > *Collections Care Grant Preparation
> >> > *Conservation Treatment of:
> >> > Furniture
> >> > Painted Wood
> >> > Horse-Drawn Vehicles
> >> > Architectural Interiors
> >> >
> >> > Marc A. Williams, President
> >> > MS in Art Conservation, Winterthur Museum Program
> >> > Former Chief Wooden Object Conservator, Smithsonian Institution
> >> > Fellow, American Institute for Conservation (AIC)
> >> >
> >> >
> >> >
> >> >
> >> > ----- Original Message -----
> >> > From: Melissa Thompson
> >> > To: [log in to unmask]
> >> > Sent: Monday, October 01, 2007 5:38 PM
> >> > Subject: [MUSEUM-L] Need help tarnishing silver
> >> >
> >> >
> >> >
> >> >
> >> > We are conducting an experiment to determine whether or not the price
> >> > of
> >> silver cloth is relative to its tarnish prevention abilities. We have
> >> three
> >> pieces of newly polished non-museum silver. One is wrapped in the
> >> expensive
> >> Pacific Silver, another is wrapped in the cheap Joann Fabric silver
> >> cloth,
> >> and the third is the control piece not wrapped in anything. We want the
> >> pieces to tarnish and are trying to accelerate the process.
> >> >
> >> > The conservator we have consulted suggested putting the pieces in a box
> >> > to
> >> control the air that has access to the objects. We are using a cooler.
> >> She
> >> told us that sulpher is a tarnishing agent and we have to introduce more
> >> sulpher into the air. Her suggestions were egg yolks, moist matches, and
> >> rubber bands. These have not tarnished the silver at all and we have
> >> been
> >> working on this for two months. Does anyone have suggestions on how to
> >> quickly tarnish silver or another way to test this hypothesis? Has
> >> anyone
> >> ever done anything similar to this?
> >> >
> >> >
> >> >
> >> > Melissa Thompson
> >> >
> >> > Collections Assistant
> >> >
> >> > Vesterheim Nowegian-American Museum
> >> >
> >> > 523 W. Water Street
> >> >
> >> > Decorah, IA 52101
> >> >
> >> > 563-382-9681 x242
> >> >
> >> > www.vesterheim.org
> >> >
> >> > [log in to unmask]
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >
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