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Triple galvanised has arrived
EXTRONA S.A.'s technical team
Viladecavalls (Barcelona)
The durability of rabbit cages depends largely on production quality in terms of combating oxidisation of the steel wire.
This is possibly more important for rabbit cages than for other species because of the "strong" composition of their urine coupled with their continual gnawing.
At EXTRONA, as a company that has produced and produces the largest number of rabbit cages in the world, each obliged to pass the strictest quality controls, we are extremely concerned to offer the public cages that, in addotion to their design, show greater productive durability.
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The best known and most widely used protection, is to protect the steel with a layer of zinc, through the galvanisation technique.
For general information and on launching our new cages with triple galvanisation, we present a scientific report on what this means.
Welded mesh for the manufacture of cages
Zinc coating
The zinc coating in galvanised wires protects the base steel of which the cages are made from atmospheric oxidisation and from chemical corrosion.
There are both national and international regulations that fix the minimum values that must be met by these zinc coatings in galvanised wires.
Nowadats in Spain and Europe there are two galvanisation qualities, depending on the thickness of the zinc coating:
- Normal galvanisation
- Reinforced galvanisation or triple galvanisation
The quantity of zinc is measured in g. per square metre of wire surface area or by microns of thickness.
The quantity of zinc is measured in g. per square metre of wire surface area or by microns of thickness.
It is clear and easy to understand that the durability of the wires is proportional to the quantity of zinc deposited on their surfaces.
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| Type of Galvanisation |
Regulation |
Quality |
Minimun zinc (gr./m2) |
| Normal |
UNE 37 506
EN 10244-2 |
G-1B
QUALITY-C |
90
100 |
| Triple reinforced |
UNE 37 506
EN 10244-2 |
G-3B
QUALITY-A |
260
255 |
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As can be seen, they are three times as thick, so manufacturing cages with triple galvanised wire guarantees at least tripling the length of time they will last.
Official laboratory tests
As proof of what is shown above, we attach a study carried out by the "Laboratori general d'assaigs i d'investigacions" (General testing and research Laboratory) of the Government of Catalonia on the behaviour of different types of wires in a salt spray chamber test under the international system.
The salt spray chamber test is the method recommended in all international regulations to evaluate the relative effectiveness of an anticorrosive covering for steel.
The test consists of measuring the time it takes for (reddish coloured) iron oxide stains to appear on the surface of steel placed in a chamber in an atmosphere saturated with humidity and salt. When the reddish iron oxide stains appear, it indicates that all the protective metal (in this case the zinc) has disappeared.
It is a comparative method, so there is no way of converting the hours measured in the salt chamber into the time it is going to last in normal conditions. What it indicates, without room for doubt, is that if a type of covering "3" has lasted three times as long in the chamber test as the type of covering "2", it is certain that the type of covering "3" is also going to last three times as long as the types "1" or "2" in the same working environment.
The test the "LGAI" was commissioned to perform was to compare three types of wire:
- 3.95 diameter normal galvanised.
- 5.00 diameter normal galvanised.
- 5.00-diameter triple galvanised (3).
In its conclusions we see that, for the same diameter of wire, the duration was:
- For the normal galvanised between 192 and 240 hours.
- For the triple galvanised it was 870 hours, that is to say, four times as long.
Welding areas in the mesh
One of the subjects that most concerns the rabbit breeder in galvanised wire cages is that the zinc covering might have disappeared at the welding points where the wires cross because of the heat generated in welding the wires and they wrongly think that because these are unprotected they are points where corrosion will appear earlier.
This argument is incorrect. The zinc covering does not act like a coat of paint on the wire that only protects the steel in a physical way, losing all its protective properties when it comes off. The zinc protects the steel electronically. This means that the aggressive environments, whether they are atmospheric or chemical, attack the zinc before the iron and they do not form iron oxide until a large quantity of zinc has been used up. Automatic welding does not cause a loss of zinc like the manual type does. So, small areas very close to large galvanised areas - as is the case with welding points in cages - are just as protected as if they were covered with zinc.
In the salt spray test it can be demonstrated in a practical and definitive way, as is the case here, that this happens. If it was true that the welding points oxidised because of lack of covering it would be at these points where the first reddish stains of iron oxide appeared and this is not the case.
In the Official Laboratory report, the theory that chemical treatments explain the process of cathodic protection is corroborated. We reproduce here a few paragraphs that corroborate what we have explained above.
It is mentioned throughout the document:
"in a general way on the surface of the samples, no preferential attack on the welded joint areas of the bars has been observed" and, another part of the document indicates: "at the time when the first symptoms of iron oxidisation are shown in the form of separate, randomly distributed red dots"
the following paragraph says:
"...neither here are the welded joints preferential points of attack."
As confirmation and as table nš2, we attach test images made by the Official Laboratory, which confirm everything said above.
We take this opportunity to guarantee that every wire made and used in EXTRONA cages is of the "triple galvanised" type and therefore they will last MORE THAN THREE TIMES LONGER because of their protection against oxidisation or rusting.
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| Official Laboratory report: |
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 FILE Nš 89.844 |
| FILE Nš 89.844/2 |
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