NATIONAL STANDARDS TCVN 5669:2013
ISO 1513:2010
PAINT AND VARNISHES - EXAMINATION AND PREPARATION OF TEST SAMPLE
1. Scope of application
TCVN 5669:2013 standard specifies a procedure for the preliminary examination of each specimen received for testing and the test sample preparation procedure by mixing and reducing a series of samples representing a consignment or bulk of paint, varnish, or related product.
2. Terms and definitions
Thixotropy
The apparent decrease in the viscosity of fluid upon application of shear stress is followed by a gradual recovery upon cessation of the application of the stress.
Homogenization
The process of combining components, particles, or layers of the primary sample (in the case of mixed samples) or of the pretreatment fraction of samples into a more homogeneous state to ensure uniform distribution of substances and sample properties.
3. Sample container
Sample container status
Record all sample container defects or any detected leaks. If the product in the container is found affected, the sample should be discarded.
Open sample container
Remove all packing material and other debris from the outside surface of the container, especially those that cling around the top of the bin. Open the container carefully, and avoid not tampering with the product inside.
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4. Preliminary test procedures for liquid products (e.g. paints) and paste products (e.g. putty)
4.1. Visual examination
4.1.1. Surface scum
Record the presence of any surface scum, whether continuous, hard, soft, thin, or excessively thick.
If scum is found on the sample, we should discard the sample. If it is impossible to remove the sample, we can completely remove the scum from the walls of the container and discard, and filter it if necessary.
For the purposes of analytical control, if the scum appears, we must disperse it into the test sample.
4.1.2. Thickness
Record the catalyzed or gelled sample, remember not to confuse gelation with catalysis.
NOTE: Both accelerated and gelled coating materials have a jelly-like consistency, which when stirred and shaken causes a marked reduction in the density of the promoted material, while the consistency of the gelled material does not change.
4.1.3. Delaminate
Record any delamination of the sample.
4.1.4. Visible impurities
When any impurities are seen, record them and remove them if practicable.
4.1.5. Clarity and color
In the case of sampling varnishes, diluents, catalyst solutions, etc., record the clarity and color of the sample.
4.1.6. Sediment
Record the type of sediment (if any), eg soft, hard or dry. If the deposit is hard, dry and crumbles when cut with a clean flat knife, describe as "dry hard".
4.2. Homogenization
4.2.1. Limitation
Samples that have gelled or have dried solid deposits (see 5.1.6) that cannot be mixed together cannot be used for testing purposes.
4.2.2. General rules
In all operations specified in 5.2.3 to 5.2.5, maximize solvent loss To achieve this, perform all operations as quickly as possible, but still maintain a good mix of consistency.
4.2.3. Remove the scum
If the priming sample has a scum layer, separate and remove all excess by filtering the fused sample through a sieve.
4.2.4. If there are no solid deposits
Mix the sample thoroughly until the sample is completely homogeneous.
During sample preparation, prevent air from entering the sample. Samples must be free of air bubbles before use.
4.2.5. If there are solid deposits
If it is necessary to examine the sample for solid deposits (but no dry deposits, see 5.2.1), proceed as follows.
Pour all liquid samples into a clean container. Scrape off the pigment deposited at the bottom of the original container with a flat knife and mix thoroughly. When the test sample is fully mixed, pour the test sample back into the original container, in small increments, carefully homogenizing before each subsequent pour. The test specimen must be free of air bubbles before use.
5. Preliminary examination procedures for powder products
For products of this type, no special examination is normally required, but abnormal conditions should be recorded such as abnormal color, the appearance of large or hard lumps, or the appearance of exotic objects.
6. Mixing and reducing the test sample
6.1. General rules
In the case of a series of samples taken from a homogeneous product, each sample may be tested separately or combined to form a reduced test sample as specified in 7.2 and 7.3.
6.2. Liquid products and paste products
After thoroughly mixing each sample as specified in 5.2, pour or transfer the sample into a clean dry container of suitable size and mix well by shaking, stirring, etc. When the mixed sample is homogenous, reduce the sample according to the provisions of ISO 15528. Store the reduced sample in one or more clean dry containers, allow 5% loss, then seal, label, and if necessary re-seal the container.
6.3. Powder products
Pour material from different sample containers into clean dry containers of appropriate size and mix thoroughly. Reduce the sample to an appropriate size, e.g. 1 kg to 2 kg, by quartering manually or by means of a rotary divider (trough divider), and then place the reduced sample in one or more containers dry clean. Cover, label, and if necessary seal the container.
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