Edouard Bastarache Inc. on wed 21 jul 04
Hehehehe Gayle,
welcome.
Later,
"Ils sont fous ces quebecois"
Edouard Bastarache
Irreductible Quebecois
Indomitable Quebeker
Sorel-Tracy
Quebec
edouardb@sorel-tracy.qc.ca
http://sorel-tracy.qc.ca/~edouardb/
http://perso.wanadoo.fr/smart2000/index.htm
http://www.digitalfire.com/education/toxicity/
----- Original Message -----
From: "claybair"
To:
Sent: Wednesday, July 21, 2004 8:24 PM
Subject: Re: Bleaching out the nasties, once again !!!
> Edouard,
>
> Thank you very much for sharing your vast knowledge!
> That was incredibly informative
> and addressed the issue precisely.
> You can rest easy now....
> I have no more questions!:-)
> Thanks again,
>
> Gayle Bair
> Bainbridge Island, WA
> http://claybair.com
Edouard Bastarache Inc. on wed 21 jul 04
Preventing Microbial Contamination
by Édouard Bastarache and Smart.Conseil
Following the proper hygiene is essential to protecting product quality and
employee health from microbial contamination.
Microorganisms exist everywhere in our environment-in the air and water, on
surfaces and on individuals. They are invisible and relatively unperceived;
however, they are very numerous-1 gram of earth can contain up to 25 billion
microorganisms (four times the earth's human population).
Microorganisms are also present in ceramic materials. While they typically
exist in harmless quantities, the presence of nutritive elements, along with
the right temperature, moisture and pH of the material, can promote the
development of harmful levels of microorganisms. Under favorable conditions,
their population can double every 20 minutes, causing the potential for
complete contamination in less than one day. Such contamination can affect
product quality and, in some cases, workers' health.
Microorganisms at a Glance
Microorganisms can vary in size from 1 micrometer (1 µ = 10-6 meter) to
several hundredths of a micrometer.
Type Size
Viruses 10 to 300 µ
Bacteria 1 to 10 µ
Family of Fungi Size
Yeasts 2 to 12 µ
Fungi 2 µ to several centimeters
Molds 2 µ to several centimeters
Lichens 2 µ to several centimeters
Algae 1 µ to several centimeters
Protozoa 2 to 300 µ
The Needs of Microorganisms
Needs Bacteria
Molds and Yeasts
Light no
no
Medium pH alkaline
acid
Temperature 20 to 40°C
20 to 35°C
Nutrients nitrogen, hydrogen,
carbon nitrogen, hydrogen, carbon
Presence of oxygen O2 or inorganics such as SOx,
NOx O2
Common Microbial Problems in Ceramics
A microbial invasion can generally be seen through changes in the color of
the surface, viscosity and pH value of the material. Such visual changes are
typically accompanied by odors and gaseous emissions, as well as variations
in the behavior of the product. Indicators containing gelose can be used to
determine the level and type of contamination. These indicators make it
possible to grow microorganisms quickly (within 48 to 96 hours) so that they
can be quantified and identified according to appearance, bacteria, yeasts
or mushrooms.
Two common places in which microbial problems occur in pottery production
are in liquid glazes and porous resin molds. The majority of disorders seen
in liquid glazes are caused by bacterial activity that modifies viscosity
and produces odors. These disorders generally occur with natural products
that contain organic matter (such as clays) under the effect of heat and
mineral concentration (such as high-density liquid glazes). A glaze that
contains glue is even more susceptible to microbial problems, because the
organic matter in the adhesives is a nutrient to bacteria.
Two distinct effects often occur with a bacterial attack in glazes:
· Fluidification due to the consumption of adhesive components used
in the glaze
· Flocculation or thickening due to the acid dejections of bacteria
following the consumption of the organic elements in the glaze
In either case, an adhesive or deflocculant can be added to the glaze
containers to correct the viscosity.
Porous resin molds for high-pressure casting are another potential problem
area. The mold capillary network is large enough (10 to 20 µ) for clay fines
to penetrate into it, and bacterial activity in the mold layer impregnated
with these fines can cause the pores to become clogged. Unlike the bacteria
problem in glazes, this situation cannot easily be corrected with a chemical
action. (When this clogging occurs on the mold's surface, the mechanical
action of a high-pressure water spray can cure the problem). The best
solution is to implement regular anti-bacterial and anti-fungal preventive
measures, such as using a forced hot air dryer to completely dry the mold
each time it is cleaned and stored.1
Opportunistic Infections
The vast majority of microorganisms are saprophytes; that is, they do not
cause infections in most situations. However, in some cases, microorganisms
can cause opportunistic infections-i.e., infections in people whose defense
mechanisms are weakened due to disease, trauma, or procedures or products
used for diagnostic or therapeutic purposes, and who are therefore
particularly susceptible to such infections. Following are a few examples:
Antibiotics. A treatment by antibiotics modifies the normal flora of the
skin, mucous membranes and digestive tract, and can lead to colonization of
these organs by new microorganisms. This colonization is generally harmless
unless it is followed by superinfection (invasion by indigenous germs or
microorganisms from the environment). Predisposing factors include:
· Chronic infections
· Debilitating diseases
· Use of excessive amounts of antibiotics
· Use of broad-spectrum antibiotics
Modifications of Anatomical Barriers. When a person's normal anatomical
barriers are broken, he or she cannot fight infections. Examples include
those suffering from extensive burns or having undergone certain therapeutic
or diagnostic procedures.
Disturbances of Cellular or Humoral Defense Mechanisms. Neoplastic and
immunodeficiency diseases can make a person susceptible to opportunistic
infections. These include leukemia, myelomas, aplastic anemia, AIDS,
gammapathies and systemic lupus erythematosus. Others in this category are
those who require treatments by radiotherapy or intensive immunosuppressive
therapy.
Cytotoxic Drugs. Those who must take cytotoxic drugs are susceptible to
opportunist infections due to a severe leucopenia (lowering of white blood
cells).
Corticosteroids. The systemic use of corticosteroids disturbs many aspects
of host defense mechanisms. Those who suffer from Cushing's syndrome
(increased secretion of an endogenous corticosteroid, cortisol) also have an
increased susceptibility to infections.
For people who have these conditions, it can be harmful to work in an
environment where high levels of microorganisms are present. It is therefore
imperative that workers are made aware of the potential dangers and that the
right preventative measures are put into place to avoid microbial
contamination.
The Role of Biocides
Biocides are products that can be used to prevent bacterial and fungal
growth. They are generally used at very low doses due to their high cost and
toxicity, and are typically introduced at the beginning of a formula or
glaze preparation in the mixing water at a rate of 0.05 to 0.50% by weight.
Biocides that combine a bactericide-fungicide with broad-spectrum activity
(containing sulfureous aliphatic and heterocyclic compounds of low toxicity)
are often used in ceramic applications. However, potters must be careful to
ensure that the right level of biocide is used. If too small an amount is
used, the biocide will not have the required effect and will give a false
sense of security. However, using too much biocide can be expensive and can
enhance its toxic effects. When used in glazes, the pH of the biocide can
also affect the rheology (thickness) of the glaze. Biocides should be chosen
for their compatibility with the product, and their pH level should be taken
into account.
Examples of some commonly used biocides include:
· Mixture of chlorinated and non-chlorinated isothiazolon compounds
(pH 3.5 +/-0.5)
· Aqueous solution of ortho-phenylphenol potassium salts (pH >13)
· 10% solution derived from oxazin with sulfur and nitrogen
heterocyclic compounds (pH 10-11)
· Aliphatic compound with sulfur heterocyclic compounds (pH 3-5)
Manufacturing Hygiene
Preventing microbial contamination and opportunistic infections in a pottery
facility is usually as simple as implementing the proper hygiene. As soon as
a bacterial contamination is noticed, the following precautions should be
taken:
Treat the water. After work containers have been cleaned, they should also
be rinsed with water containing a biocide to destroy any residual
microorganisms.
Introduce a biocide at the beginning of manufacturing. The biocide must be
added to the product at the beginning of the aqueous phase preparation
(product to be protected + workshop water + biocide) to ensure that the
product is adequately protected and to prevent its properties (mainly
viscosity) from being altered by the biocide's pH level.
Protect liquid organic additives with a biocide. Liquid additives containing
organic matter must also be protected with a biocide to prevent them from
acting as carriers of contamination when they are introduced into the
process (i.e., in liquid glazes in which an aqueous glue such as CMC is
introduced, the glue should be treated with a biocide when manufactured to
ensure its preservation).
Thoroughly clean facilities. Use a disinfectant (such as sodium hypochlorite
or bleach*) mixed with water to clean containers in which a contaminated
product has been stored.
Other preventative steps include:
· Use disinfectants during cleaning
· Avoid complex and difficult-to-clean piping (dead lines)
· Keep pipes and containers empty and dry when not in use
· Beware of dust
By knowing what to look for and following the right preventative steps,
potters can prevent microbial contamination problems, thereby protecting
both their product quality and their workers' health.
NOTE:
*While bleach is an excellent disinfectant, its high pH and short-duration
effect make it a temporary cleaning material only. It is not very compatible
with ceramic products as a stable protective biocide.
Biocide Suppliers
Following are some companies that supply biocides for use in ceramic
products:
1) Acti-Chem Specialties, Inc., 56 Quarry Rd., Trumbull, CT 06611; (203)
365 6530; fax (203) 365 6537; e-mail acti@actichem.com;
http://thor.adept.co.uk
2) Dow Chemical Co., P.O. Box 1206, Midland, MI 48642; (989) 832-1560 or
(800) 447-4369; fax (989) 832-1465; e-mail dowcig@dow.com; www.dow.com
3) SEPPIC Inc., 30 Two Bridges Rd., Suite 210, Fairfield, NJ 07004-1530;
(973) 882 5597; fax (973) 882 5178; e-mail info.seppic@airliquide.com;
www.seppic.com
4) R.T. Vanderbilt, P.O. Box 5150, Norwalk, CT 06856-5150; (203)
853-1400; fax (203) 853-1452; e-mail rjohnson@rtvanderbilt.com;
www.rtvanderbilt.com
5) Zschimmer & Schwarz (France), 10 rue Saint-Marc, 75002 Paris, France;
(33) 1-42-33-10-33; (33) 1-40-26-23-81; e-mail zsf.cuir@wanadoo.fr;
www.zschimmer-schwarz.com
Reference:
Shulman, Stanford T.; Phair, John P.; Peterson, Lance; and Warren, John II,
The Biological and Clinical Basis of Infectious Diseases, 5th ed., WB
Saunders Co., 1996.
----- Original Message -----
From: "claybair"
To:
Sent: Wednesday, July 21, 2004 12:09 AM
Subject: Re: Bleaching out the nasties (was clay meat, one veg)
> So....
> I guess the questions then are:
> Is there a stable protective biocide
> compatible with ceramic products?
> And
> Are they safe to use?
>
> I'm not saying I would run out to get it
> or even use it but there have been people
> with compromised immune systems whether
> it be allergies or something more serious
> who have asked that question before.
>
> Gayle Bair
> Bainbridge Island, WA
> http://claybair.com
>
> -----Original Message-----
> From: Edouard
> Bastarache Inc.
>
> Hello all,
>
>
> Bleach
>
>
> Bleach is not an adequate biocide because if one uses bleach as a
> preventive biocid in the conservation of a ceramic product containing
> organic matter, its short duration effect will not be able to effectively
> protect this product over time.
>
> Bleach can be used as a disinfecting material for cleaning, with a
> temporary and effective action, containers and other equipment. But, it
is
> not not compatible with ceramic products for ensuring their conservation,
> i.e:
> - its high pH, which deflocculates clays at the beginning of its
> introduction into a liquid glaze, decreases thereafter producing the
> opposite effect (flocculation), which can be disastrous for the ceramicist
> (worse than the bacteria), if he has set the viscosity of his product
right
> after having introduced bleach.
> - Or the effect of the bleach pH is straightforwardly incompatible with
the
> product because it causes too great modifications of its properties
>
> Conclusion :
> Bleach is an excellent disinfectant, but its high pH and its short
duration
> effect make it a temporary cleaning material not very compatible, as a
> stable protective biocide, with ceramic products
>
>
>
> Smart.Conseil and I
>
>
>
> Later,
>
>
>
> "Ils sont fous ces quebecois"
> Edouard Bastarache
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
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> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
claybair on wed 21 jul 04
Edouard,
Thank you very much for sharing your vast knowledge!
That was incredibly informative
and addressed the issue precisely.
You can rest easy now....
I have no more questions!:-)
Thanks again,
Gayle Bair
Bainbridge Island, WA
http://claybair.com
-----Original Message-----
From: Edouard Bastarache Inc.
Preventing Microbial Contamination
by Édouard Bastarache and Smart.Conseil
Following the proper hygiene is essential to protecting product quality and
employee health from microbial contamination.
Microorganisms exist everywhere in our environment-in the air and water, on
surfaces and on individuals. They are invisible and relatively unperceived;
however, they are very numerous-1 gram of earth can contain up to 25 billion
microorganisms (four times the earth's human population).
Microorganisms are also present in ceramic materials. While they typically
exist in harmless quantities, the presence of nutritive elements, along with
the right temperature, moisture and pH of the material, can promote the
development of harmful levels of microorganisms. Under favorable conditions,
their population can double every 20 minutes, causing the potential for
complete contamination in less than one day. Such contamination can affect
product quality and, in some cases, workers' health.
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