Texas Comptroller of Public Accounts

Texas Comptroller of Public Accounts, Glenn Hegar

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Texas Specification No. 505-85-03A

(Supersedes Texas Specification No. 505-85-03)

Effective Date: January 1, 1979

Reformatted: 19, 1996





1. SCOPE: This specification establishes the minimum requirements for sodium silicofluoride (Na2SiF6), also known a sodium fluosilicate, for use as a laundry sour.

2. APPLICABLE SPECIFICATIONS AND STANDARDS: References to specifications, standards and test methods shall be to the issues in effect on the date of the Invitation for Bids. Copies of the referenced documents may be obtained from the issuing organizations at the addresses shown. The following publications form a part of this specification to the extent specified herein:

2.1. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM), 1916 Race Street, Philadelphia, PN 19103:

2.1.1. ASTM D 502 - Standard Method of Test for Particle Size of Soaps and Other Detergents.

2.1.2. ASTM E 70 - Standard Method of Test for pH of Aqueous Solutions with the Glass Electrode.

3. DEFINITIONS: Terminology used in this specification is intended to be generic in nature and consistent with meanings that have been defined through general use and/or accepted trade practices. Where variant meanings may exist, the applicable interpretation shall be determined by the Texas Procurement and Support Services (TPASS).

3.1. COMMISSION: Texas Procurement and Support Services (TPASS).

4. REQUIREMENTS: Sodium silicofluoride furnished under this specification shall meet or exceed the following minimum requirements:

4.1. GENERAL REQUIREMENTS: The product shall be a colorless, odorless, free flowing crystalline salt having the chemical formula Na2SiF6.

4.2. CHEMICAL AND PHYSICAL REQUIREMENTS: The chemical and physical properties listed in Table 1; Chemical and Physical Requirements, shall fall within the indicated limits, when tested by the methods cited in Paragraph 6.



Requirement Minimum Maximum Test Paragraph
Percent active Na2SiF6 97.5 -- 5a
Moisture -- 0.5 5b
Insoluble Matter -- 0.5 5c
pH of a saturated solution at 25 °C 3.2 3.5 5d
Particle Size: % through No. 40 Screen 95 -- 5e
Particle Size: % through No. 325 Screen -- 25.00 5e

5. SAMPLES: Unless otherwise specified in the Invitation for Bids, no prepurchase samples shall be required. Samples tested shall be taken from regular orders.

6. TESTING: Testing shall be done by or at the direction of, the Commission and/or the receiving State agency. Tests shall be performed on products from shipments to ordering agencies. In the event products tested fail to meet or exceed all conditions and requirements of this specification, the cost of the samples used and the cost of testing shall be borne by the supplier.

6.1. TESTS: The product furnished under this specification shall be tested by the following methods or approved equally applicable procedures:

6.1.1. Percent Active Na 2SiF6: Prepare a potassium chloride solution by dissolving 60 g KC1 in 400 ml distilled water, then adding 400 ml neutral 95% ethanol. Weigh accurately into a beaker about 0.4 g laundry sour. Add 50 ml KC1 solution and stir until reaction is complete. Filter out the precipitated potassium silicofluoride on a Gooch crucible with a disk of filter paper and a medium pad of asbestos. Wash the precipitate with two portions of KC1 solution. Transfer the contents of the crucible quantitatively to a 400 ml beaker with the aid of about 100 ml distilled water from a wash bottle. Place the beaker on a combination hot plate / magnetic stirrer, and heat the contents to the boiling point. Titrate to a phenolphthalein end point with 0.2 N sodium hydroxide. Calculate percent sodium silicofluoride by means of the formula

% Na2SiF6 = ml NaOH x normality x 4.7

g sample Determine compliance with Paragraph 4.2.

6.2. Moisture: Weigh a 5 g sample into a broad weighing bottle. Heat in an oven at 105 °C for two (2) hours, or until constant weight is reached. Cool in a desiccator, and weigh. Calculate percent loss in weight, and determine compliance with Paragraph 4.2.

6.3. Insoluble Matter: Dissolve a 2 g sample in 500 ml hot distilled water. Collect the un-dissolved residue on a tarred Gooch crucible or fretted glass filter of medium porosity. Wash with distilled water until the washings are fluoride free. Dry and weigh the filter as in Paragraph 6.2. Calculate the percent insoluble matter, and determine compliance with Paragraph 4.2.

6.4. pH: Prepare a saturated solution by shaking 1 g or more of sample with 100 ml distilled water at room temperature. Determine compliance with Paragraph 4.2 by the procedure of ASTM E 70.

6.5. Particle Size: Determine compliance with Paragraph 4.2. by the procedure of ASTM D 502.

7. INSPECTION: Products furnished under this specification shall be inspected by, or at the direction of the Commission and/or the ordering State agency either at the destination or place of manufacture.

8. PACKING / PACKAGING: Packing for shipment shall be in accordance with the manufacturer's standard practice and in a manner readily accepted by common carriers engaged in interstate commerce. Within the shipping carton, units shall be packed in a manner designed to minimize damage during the shipment because of rough or improper handling.

8.1. PACKING: The product shall be packaged in one of the following types and sizes of new containers:

8.1.1. Multiwall paper bags of 100 pounds (45.4 kg) net contents.

8.1.2. Fiber drums of from 100 pounds (45.4 kg) to 400 pounds (181 kg) net contents.


9.1. MARKING: Each shipping container shall be clearly marked with the following data:

9.1.1. Name of contents.

9.1.2. Quantity contained.

9.1.3. Order number or contract number.

9.1.4. Name and address of ordering agency.

9.1.5. Agency requisition number.

9.1.6. Name and address of manufacturer.

9.1.7. Warning statements as required by government regulations.

10. COMPLIANCE: In order for consideration to be given to the bid on an item under this specification, the bidder must comply with the following:

10.1. PRODUCT IDENTIFICATION: The make, model number, name of the manufacturer, brand or trade name, etc., as applicable, of the item which the vendor proposes to furnish must be stated as part of the bid.

10.2. EXCEPTIONS: Notwithstanding the above, any exception taken by the bidder to the requirements and conditions of this specification must be stated and described in detail as a part of the bid. If no exceptions or deviations are identified in this manner, the items must be furnished exactly as described herein.

10.3. PROOF: The bidder shall bear the burden of proof of compliance with this specification.

11. ORDERING DATA: When ordering products conforming to this specification the requisitioning agency shall specify the following:

11.1. The number of this specification (505-85-03A).

11.2. The type, size and number of containers (See Paragraph 8).

11.3. The total quantity desired.

12. PRODUCT INFORMATION: Although sodium silicofluoride is not a strongly acidic material under ordinary conditions, it readily neutralizes laundry alkalis in hot water. Like all soluble fluorine compounds, it is very poisonous in concentrated form. Safety precautions should be taken in handling to prevent contact with the skin or inhalation of fine particles. In case of accidental swallowing, call a physician immediately. If a physician's immediate advice is not available, large amounts of milk may be given as a first aid measure.

13. AVAILABILITY OF SPECIFICATIONS: Copies of this specification may be obtained by calling or writing:

Bid Services

Texas Procurement and Support Services

P.O.Box 13186

Austin, TX 78711-3047

(512) 463-3416

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