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Toxics Use Reduction Institute · Surface Solutions Laboratory
Toxics Use Reduction Institute

Surface Solutions Laboratory

Trial Report

Trial Number 0

(Client Number 27, Project Number 1)

Trial Purpose: Goal of trial is to find a cleaning method

Date Run: 05/08/96

Experiment Procedure:
The goal of this trial is to find a viable method for Ceramic Coating Company to clean of their screens. Three different criteria was used to determine the effectiveness of a claning method:

1) Cleanliness- The new method must remove most of the baked on clay/silicon dioxides fromt the screens.
2) Economically Viable- The new method must be cost effective and should also require as little equipment as possible and must not damage the screens.
3) Environmentally Friendly- The new method must not add to or create hazardous waste and/or worker exposure.
From the above listed criteria, two different methods were selected to be tested. The first method was to use an environmentally friendly cleaning chemical to remove the baked on clay/silicon dioxide. Nine different chemicals were chosen on the basis of strength and classification.
The sample screens obtained from Ceramic Coating Company were cleaned in a one liter full-strength solution of each chemical. Cleaning was performed for 30 minutes at 120 F in a beaker agitated with a stirbar. Cleaning effectiveness was observed by visual inspection.
The second method to be tested was a sodium bicarbonate blasting process used at AA Environmental in Woburn, MA. The sodium bicarbonate blasting is similar to sandblasting except it is virtually nondestructive and the blasting material is water soluble and non-hazardous so it can be washed away. AA Environmental is basically a contract cleaning company whom will come down to one?s facility to perform the cleaning, but he sodium bicarbonate blasting equipment can also be purchased through them if so desired.

SUBSTRATE MATERIAL: Teflon coated steel screens
CONTAMINANTS: Baked on Kaolin Clay/Silicon Dioxide
CONTAMINATING PROCESS USED: As recieved from Ceramic Coating Company.

Trial Results
The first part of the test proved to be unsuccessful.  The only chemical that even touched the clay/silicon dioxide was the W.R. Grace 294xx.  From
the long contact time needed for a full strength solution, this part of testing was deemed unviable and was not explored any furter.
The sodium bicarbonate blasting proved to be very effective.  All of the clay/silicon dioxide was removed from one half of a screen in less than a

Success Rating
Results successful using TACT (time, agitation, concentration, and temperature, as well as rinsing and drying) and/or other cleaning chemistries examined.

The one problem with the blasting was that the Teflon was also removed.