BS 391:1987 download free.Specification for Tung oil for paints and varnishes [ISO title: Raw tung oils for paints and varnishes — Specifications and methods of test].
1 Scope and field of application
BS 391 specifies the requirements and the corresponding methods of test for two types of tung oil suitable for paints and varnishes. It is not intended to apply to tung oils which are wholly or partly solidified as a result of polymerization.
2 References
Iso 150, Raw, refined and boiled linseed oil for paints and varnishes — Specifications and methods of test.
Iso 654, Short solid-stem thermometers for precision use.
ISO 842, Raw materials for paints and varnishes — Scvnpling1.
ISO 3681, Binders for paints and varnishes — Determination of saponification value — Titrimetric in eth od.
ISO 3682, Binders for paints and varnishes — Determination of acid value — Titrimetric method. ISO 3838, Crude petroleum and liquid or solid petroleum products — Determination of density or relative density — &ipillary-stoppered pyknometer and graduated bicapillary pyknometer methods. Iso 4630, Binders for paints and varnishes — Estimation of colour of clear liquids by the Gardner colour scale.
ISO 5661, Pet rolcumn products — Hydrocarbon liquids — Determination of refractive index.
3 Definitions
3.1
raw tung oil
the product obtained directly by expression or extraction from the seeds of different species of the genus Aleu rites (family of Euphorbiaceae) only
3.2
type F oil
raw tung oil derived substantially from seeds of the species Alcu rites fordii Hemsley
3.3
type M oil
raw tung oil derived substantially from seeds of the species Aleurites montana Wilson
4 Required characteristics and their tolerances
Raw tung oils shall have the characteristics shown in the Table.
Each tube shall have a cork, having a hole through which a glass rod of diameter 3 mm can move freely.
8.1.2 Oil-bath, of 120 mm diameter and 160 mm height.
Suitable media for use in the bath are soya bean oil, cottonseed oil, medicinal liquid paraffin or carnauba wax.
8.1.3 Thermometer, STC/0,51245/305 complying with the requirements of ISO 654.
8.1.4 Stop-clock
8.1.5 Glass rods, of diameter 3 mm.
8.2 Preparation of test sample Mix the sample of oil thoroughly by shaking.
8.3 Procedure
Carry out the procedure in duplicate.
Pour 5 ml of the test sample (8.2) into one of the test-tubes (8.1.1) and fit the test-tube with the cork (see 8.1.1) and the glass rod (8.1.5).
Place the test-tube in the oil-bath (8.1.2), containing 500 ml of oil heated to a temperature of 275 to 277 °C. Support the test-tube so that its bottom is approximately 15 mm above the base of the bath. Similarly support the thermometer (8.1.3), with the bottom of its bulb approximately 15 mm above the base of the bath, adjacent to the test-tube.
Start the stop-clock (8.1.4) and when the test portion has been in the bath for 12 mm, raise the glass rod approximately 10 mm at intervals of 15 s. Record the time when the test portion has gelled, as shown by the test-tube rising with the rod. Immediately remove the test-tube from the bath, allow it to cool to room temperature and examine the jelly, which shall be firm, non-sticky and capable of being cut cleanly with a sharp knife or scissors. If the results differ by more than 30 s, repeat the test on another two 5 ml test portions of the oil.
9 Insoluble bromide test
9.1 Reagents
9.1.1 Diethyl ether
9.1.2 Bromine
9.2 Preparation of test sample
Mix the sample of oil thoroughly by shaking.
9.3 Procedure
Dissolve I ml of the test sample (9.2) in 20 ml of the diethyl ether (9.1.1) in a test-tube or small flask. mix the solution well and place the container in cold water.
Add bromine (9.1.2) from a fine pipette, drop by drop, avoiding vigorous action, until a considerable excess is present. as indicated by a persistent strong red colour. Shake the container well, allow to stand in cold water for 15 mm and examine the solution. If the solution is clear, this indicates that no insoluble bromide has been formed.
10 Test for presence of mineral acid
Shake 10 ml of the oil with 25 ml of water. Draw off the aqueous layer and add a few drops of litmus solution or a litmus paper. In the presence of mineral acid, the colour turns to red.
11 Test report
The test report shall contain at least the following information:
a) the type and identification of the product tested:
b) a reference to this International Standard
(ISO 277);
c) the results of the tests, and whether or not the product complies with the relevant specification limits;
d) any deviation, by agreement or otherwise, from the procedures specified;
e) the date(s) of the test(s).