Linolie til overfladebehandling af udvendigt træværk - Materials.dk

10.4 Research results
10.4.1.1 Product imperfections
There is a difference in the quality of linseed oil products, which is partly due
to the fact that there is generally too little knowledge of the factors influencing
the properties of linseed oil. But a number of product imperfections also
suggest that not everybody in the trade has the necessary professional
background and expertise:
• missing production tests
- usually paint and varnish producers save tests of the production so that it
is possible later to examine the tests as a way of getting through to some of
the causes of the apparent imperfections - however, some in the linseed
oil business are not in line with that.
• ack of knowledge of basic chemistry
- when introducing e.g. products containing boron (boron is a fungicide)
as totally harmless and almost eatable in spite of the fact that boron is
suspected, among other things, of giving embryonic damages, and that it
is on the list of substances that should be phased out;
- when marketing a thinner for linseed oil paint that takes longer to
evaporate than the linseed oil takes to dry
• contents of unhealthy substances
- especially organic solvents such as turpentine which some products
contain to a greater or smaller extent – and which is usually not necessary
• missing documentation on products that are sold in connection with linseed oil
- like e.g. citrus seed oil, by some manufacturers introduced as a natural
and harmless fungicide with no documentation of the correctness of this
and without information of possible unhealthy effects.
• missing quality control and homogeneity in the production
- products from the same manufacturer, that ought to be alike, may vary
in properties and quality from product to product
• too much or wrong filler
- filler is added partly to make the paint fuller (which means that the
viscosity is enhanced to make the application easier), and partly to make it
cheaper – but otherwise it has no function; in the previously mentioned
example of adding thinner - this need for thinner was due to adding too
much filler!
- chalk is often used as filler but along with the subversion of the linseed
oil it will become visible as chalking; the surface becomes lustreless and
gradually gets a white foggy surface; at the same time it becomes more
susceptible to humidity – this is especially distinct upon dark painting
surfaces
It should be stressed that also a lot of good products are found on the market.
The problem is the difficulties of finding out which products are good and
which are not. One can ask for technical data but there is a great difference in
the level of information since no standards exist for what they should contain.
One can check if a so-called CE/EN 927 test has been carried out (where a
skirting board with paint is exposed outdoor for a year).
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