Abrasion resistance is one of the most requested tests especially in the performance evaluation of wood flooring, but sometimes it is perhaps not really clear what are it real meaning and scope. Therefore, with these brief notes we would like to analyse this type of test also considering the existence of various types of methods and, in some cases, of specific requirements.
First of all, we would like to remember that the word abrading derives from the union of two Latin words, that is ab (which means "from") and radere (scraping). The meaning of abrading is therefore literally to "take away scraping".
Why is it therefore important to perform the abrasion test on the surface of a wooden floor? Because the resulting data gives us information on the resistance of surface treatment to wear resulting mainly from the continuous "scraping" caused by the soles of the shoes with which we walk above. Once the protective coating has been completely worn out, the wood will obviously not be protected and will therefore be able to get dirty, stain and scratch very easily. The greater the abrasion resistance, the longer the floor will last before having to be repainted.
Is the abrasion resistance test so important for any floor and in the same way? Well, here many variables come into play on which it is certainly worth making some considerations.
First of all it is clear that this test can have little or even no significance for
wax or oil-treated floors. The waxing and oiling have in fact the great advantage of being able to be easily restored and therefore the rapid "consumption" of the surface protection is inherent in these treatments. An abrasion test would simply show a lack of resistance that would nevertheless be completely obvious and predictable.
For all other finishes the abrasion test is instead relevant, but must still be evaluated with extreme attention considering especially the intended use of the floor. It is clear, for example, that we will be able to tolerate much lower values for a floor destined for a bedroom than we can imagine necessary for a store or an airport. It is obviously a matter of balancing aesthetic features with performance always finding the right compromise.
Here, however, a distinction must be reported regarding
floors made of veneered panels. In these cases, the floor could not be repainted because the necessary preliminary sanding would consume the entire veneer layer. Therefore, the resistance to abrasion of the surface of these floors must be very high and it is not by chance that the European standard EN 14354 establishes values that, if not examined in depth, may even appear excessive.
The sense, however, is to protect a floor that cannot be restored after the paint has been "scraped off" by the effect of daily wear.
What are the methods used to evaluate the resistance to abrasion of a floor? The methods are substantially two and both provide for abrading the surface of the floor, placed in rotation, by an abrasive material. In one case the abrasive material consists of two abrasive wheels (there are actually several types), while in the other it is simply sand that is dropped in a controlled manner on the specimen above which leather-covered wheels rotate.
Abrasion resistance is expressed by the number of revolutions necessary to remove the coating film from the surface of the specimen.
It must be added that there are also other methods that are used to evaluate the abrasion resistance of the only coating. In these cases the coating material is applied on an inert substrate, then rotating the abrasive wheels on the surface of the sample for a certain number of revolutions, but never reaching the substrate. The weight loss of the specimen is measured. The more resistant coating will be, evidently, the one which suffer the least weight loss with the same number of rotations. Basically the less "scrapable" coating will be better.
Obviously, in these cases it is the single coating that has to be tested and not the whole coating system.
But beyond the methods are there any requirements for the resistance to abrasion of wooden floors? As already indicated, the only European standard that contains requirements is that which refers to floors made of veneered panels (EN 14354). However The values shown in this standard are not extendable to parquet floorings for the reasons that we have previously expressed.
A very interesting and complete document concerning the parquet is that prepared by the German producers in collaboration with the IHD Institute in Dresden. In this protocol, six classes of final use of parquet are indicated with a clear distinction for the resistance to abrasion (according to the method of abrading wheels) ranging from 50 rpm for a floor intended for domestic use up to 200 for those subject to intensive use (eg commercial). In this regard, it is possible to point out that
in Germany they are proceeding towards a further expansion of the requirements (currently a dozen), as they are also studying a new method to evaluate the wear resistance of oiled or waxed floors. It is a very innovative method and of a certain complexity also from an operative point of view.
Finally, it can be concluded that the abrasion resistance method of wooden floor surfaces can provide very useful information on their performance and durability over time. Unfortunately, as mentioned previously, there are currently various methods defined according to different standards, but there is no a reference, especially as regards to the definition of a "minimum requirement" depending on the intended use. It is undeniable that this situation brings with it much uncertainty or even confusion, especially in the case of disputes.
In these few lines, however, we have noted the existence of a completely different situation for the German market where there is a very clear and detailed parquet protocol. The German producers clearly see in the rules of the tools to improve and protect their production, as well as being able to deal with possible disputes in a serene and above all objective way. Perhaps such an initiative, considering the importance and the peculiarity of Italian parquet, would be desirable also for our country.
For info:Franco Bulian
+39 0432 747231
bulian@catas.com
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