The quantitative grades are manufactured from top quality cotton linters using ultra-pure, reverse-osmosis water and are further treated with dilute acid to remove any remaining organic and inorganic impurities. All quantitative grades are manufactured in a strictly controlled environment that ensures high uniformity and high purity from filter to filter.
Low ash content 0.007% (Acid-wash treated)
Ashless Grades (Ash 0.007%)
These standard ashless grades are high purity filter papers suitable for routine quantitative gravimetric techniques and in the preparation of samples for use in analysis involving instrumental techniques.
Grade 94: 1.5µm – Slow Speed
This is an extremely fine retention filter for critical gravimetric analysis of very fine particles such as barium and lead sulfates, stannic and nickel sulfide, calcium oxalate and calcium fluoride.
Environmental Laboratory Applications:
STM 3500-PB Lead Detection: Dithizone Method
Preparation of the dithizone includes filtering through a paper, such as Grade 94. During the sample digestion the sample is filtered through a leadfree filter paper, such as Grade 55.
Grade 94 is used in preparing the DAN solution that is a reagent in the method. It can also be used in the general analytical scheme for determining which species of selenium are in the sample.
STM 3500-V Vanadium Detection: Gallic Acid Method
Grade 94 is used for preparation of the gallic acid solution required for each sample set.
STM 4500-P.C Phosphorus in Water: Vanadomolybdophosphoric Acid Colorimetric Method
During sample preparation a glass fiber filter may be used as a pre-filter before the membrane filter. Grade 161 is suitable. Activated carbon is mixed into the test solution to remove interfering elements. The carbon is then filtered out using Grade 94, which will not impart any contaminates to the filtrate and will retain all the activated carbon.
The precipitate is collected on a paper filter, such as Grade 94, or a glass fiber filter, such as Grade 169, to measure its weight and radioactivity.
Mining Laboratory Applications:
ASTM D2492-02 Forms of Sulfur in Coal
Grade 74 is used during the initial extraction and to determine the percent of pyritic sulfur. Grade 54 and Grade 94 are used to determine the percent of sulfate sulfur.
ASTM D3177-02 Total Sulfur in the Analysis Sample of Coal and Coke
There are two filtration stages in this procedure. The first stage requires a qualitative filter to remove the nondissolved portion of the digested material. Grade 601 is recommended for this step. The second step requires a quantitative filter for collecting and measuring barium sulfate precipitate. Grade 94 is recommended for this step.
ASTM D5263-93 Determining the Relative Degree of Oxidation in Bituminous Coal by Alkali Extraction
The amount of humic acid present in coal correlates to the degree of oxidation. Because of the high solids loading, and presence of fines, the test recommends using a bi-layer filter. Grade 74 is used as the pre-filter and Grade 94 as the main filter. This will provide the necessary filtration and ash properties needed for the procedure.
Construction Laboratory Applications:
ASTM C114-11b Chemical Analysis of Hydraulic Cement
Hydraulic Cement is tested for the presence of multiple elements with this procedure. Quantitative filters, Type II ASTM 832 E, F and G (Grades 54, 74, and 94 respectively) are recommended for various steps in the process.
ASTM C941-10 Water Retentivity of Grout Mixtures for Preplaced-Aggregate Concrete in the Laboratory
The water retentivity of concrete aggregates is determined with this test. The retentivity indicates the ability of the mix to retain water, which relates to the elasticity of the material. A Buchner funnel with ASTM 832 Type 2 Class G filter, Grade 94, is used to vacuum filter a sample.
ASTM D806-96 Cement Content of Soil/Cement Mixtures
The cement content of a dry soil/ cement mixture is determined with this procedure. There are several steps, all of which require filter paper. The first extraction is done with Hydrochloric acid; Grade 601 is recommended. The filtrate is precipitated and filtered with Grade 54. Again the filtrate is treated and re-filtered with Grade 601. The final precipitate step is filtered with Grade 94.
ASTM D5298-10 Measurement of Soil Potential (Suction) Using Filter Paper
Laboratory filter paper is used as a passive sensor to evaluate the soil matrix and total potential (suction). The filter paper is enclosed with the soil sample until moisture equilibrium is reached. Grade 94 is commonly used for this procedure.