the People's Republic of China national standards

Methods of sampling shellac products GB 8142-2008

Methods of sampling lac products

Foreword

This standard supersedes GB/T 8142-1987 Methods of Sampling Lac Products.

Compared with GB/T 8142-1987, this standard mainly involves the following changes:

-In Chapter 1, "Introduction" is changed to "Scope", and "Other" is deleted;

-The requirements for particle size of sample preparation are modified;

-The requirements for sample preparation for analysis are added.

This standard is proposed by the State Forestry Administration.

This standard is under the centralized management of the Institute of Forest Products Chemical Industry, Chinese Academy of Forestry.

This standard was drafted by the Institute of Forest Chemical Industry, Chinese Academy of Forestry.

Main draftsmen of this standard: Wang Yongmei, Chen Jiahong, Wu Dongmei and Wu Zai Song.

The previous versions replaced by this standard are:

--GB/T 8141-1977

1 Scope
                          

This standard specifies the sampling method, sample preparation and sample preservation of shellac products.

This standard applies to the sampling of granular shellac, shellac, decolorized shellac, dewaxed shellac, decolorized and dewaxed shellac, military shellac, bleached shellac and dewaxed bleached shellac.

2 Sampling methods

2.1 number of samples collected

The analysis sample should be sufficiently representative of a whole batch of material. The samples for inspection shall be selected from not less than 10% boxes (bags), at least 5 boxes and not more than 25 boxes at most from each batch of products, and shall be taken from different parts of the original unopened boxes (bags).

Sampling of 2.2 Loose Shellac Products

For the sampling of general loose shellac products, a sampling spoon can be used to extract approximately the same number of samples from different parts of each box (bag), with a total weight of about 5kg.

Sampling of 2.3 caked shellac products

For clumped shellac products, samples are split or chiseled from different parts, and the amount of samples taken from each box (bag) is approximately equal, with a total weight of about 5kg.

3 Sample preparation

3.1 laboratory samples

Fully mix the extracted samples, divide them by quartering method, take two pairs of diagonal samples and fully mix them, divide them into four equal parts, mix the two pairs of diagonal samples, grind them until they pass through a sieve with an aperture of about 2mm (equivalent to 10 mesh) and fully mix them, and divide them into four equal parts, each part is about 300g.

3.2 analysis sample

3.2.1 

Take 100g of laboratory sample (3.1), crush it until it completely passes through a sieve with an aperture of about 0.4mm (equivalent to 40 mesh), and put it into a clean, dry glass wide-mouth bottle with a grinding mouth for analysis and inspection. Stick a label on the bottle and indicate the name of the manufacturer, product name, batch number, sampling date and location, etc.

3.2.2 

Take 40g of laboratory sample (3.1), crush it until it completely passes through a sieve with an aperture of about 0.3mm (equivalent to 60 mesh), and put it into a clean, dry glass wide-mouth bottle with grinding mouth for analysis and inspection. Stick a label on the bottle and indicate the name of the manufacturer, product name, batch number, sampling date and location, etc.

3.2.3 

Take 10g of laboratory sample (3.1), crush until it completely passes through a sieve with an aperture of about 0.2mm (equivalent to 80 mesh), and put it into a clean, dry glass wide-mouth bottle with a grinding mouth for analysis and inspection. Stick a label on the bottle and indicate the name of the manufacturer, product name, batch number, sampling date and location, etc.

4 Preservation of samples

The remaining 150g laboratory sample (3.1) shall be put into a clean and dry wide-mouth bottle, sealed, and the bottle shall be labeled with the same content as 3.2.1, and shall be stored for later use.