When we talk about coating, we mean the surface treatment. So what is a surface treatment? What is it used for ? How to choose it according to the support? We decipher all the characteristics of the coatings for you.
A surface treatment takes place during the manufacturing process and corresponds to all operations aimed at modifying the appearance of the surface of a material, in order to adapt it to specific conditions of use.
It therefore improves a specific aspect of the screw: either the surface appearance, or corrosion resistance, or even friction resistance or to provide better resistance to wear.
The coating is deposited over the entire surface of the screw by a coating process. In our ROCKET wood screw ranges, we have 4 types of materials:
Bichromate steel is a hard zinc coating. It has long been favoured in the manufacture of parts (especially automotive) because it has the characteristic of improving all the technical aspects of the screw.
This surface coating is carried out in two stages: zinc plating and passivation in a chromic bath. “Passivation is a layer created on a coating to provide sacrificial protection to reduce the rate of corrosion of the metal coating and therefore to provide more durable protection and / or to achieve coloration.”
This coating gives a yellow color to the screw, which allows it to blend well with the wood. The white zinc-plated screw is also commonly used, especially in carpentry, since it matches easily with furniture hardware.
Technically, the screw with one or the other coating is identical. Today with the new manufacturing processes there is no longer any difference even on the corrosion resistance which was previously better with bichromate steel. In all cases, for these two types of coating, it is recommended to use them indoors but can also be used in sheltered outdoors.
– Countersunk head wood and chipboard screws (cardboard box and vybac): Ø3 to 6, length 10 to 200.
– Hexagonal woodscrew : (cardboard box and vybac): Ø6 to 10, length 40 to 160
– Hinge screw: (cardboard box and vybac): Ø6 and 7 up to length 20 to 120
– Countersunk head wood and chipboard screws (cardboard box): Ø3 to 6, length 10 to 200.
– Round head wood and chipboard screws (cardboard box): Ø3 to 6, length 10 to 80.
– Hexagonal woodscrew (cardboard box): Ø6, length 40 to 160.
– Countersunk head and large flat head frame screws: (cardboard box): Ø6 and 8, length 60 to 400.
– Flooring screws (cardboard box and vybac): Ø3.5, length 35 to 55.
With the exception of certain coatings which deteriorate on contact with air or water, stainless steel is made of alloys that allow it to better resist corrosion. It acts against oxidation in air (salty seaside air) and in humid environments. The additives of this material are mainly chromium and nickel. A2 stainless steel can be used indoors (bathrooms, for example) as well as outdoors in humid environments (garden, terrace, etc.) that can affect the screw.
Even if we do not have an A4 stainless steel range, you should know that this one has an even higher quality and offers an even stronger corrosion resistance. It is used in very humid environments such as swimming pools, seaside and in the maritime (boat…).
ROCKET carries out salt spray tests on the different materials of its screws and those on the market in order to compare those which are better in corrosion resistance,. The screws to be evaluated are placed in a chamber in which an atmosphere conducive to corrosion has been created by vaporization of a salt solution which attacks the screws. The results simply allow them to be compared with each other and to classify the different materials according to corrosion resistance because there is a common reference system at the global level.
– Wood and countersunk head chipboard (cardboard box and vybac): Ø3 to 6, length 16 to 160.
– Terrace (cardboard box and bucket): Ø5, length 50 to 80.
– Hinge (cardboard box and vybac): Ø6 and 7, length 20 to 70.
Black coated steel screws are made with steel coated with a thin layer of zinc. This surface treatment significantly improves the resistance of the screws against corrosion.
We have the hinge screw (cardboard box and vybac): Ø6 and 7, length 20 to 70.