frequently asked questions
Below you will find answers to a large number of questions. If your question is not listed, don’t hesitate to contact us.
Rotomoulding is a coating technique in which the part to be coated is heated and turned. The coating material will be distributed all over the surface and will melts down as a solid layer.
The advantage of rotomoulding is that tanks and pressure bottles with small openings for instance can be provided with a solid coating.
Kersten uses Rilsan® combined with this technique. Other coatings are available on request.
Electrostatic powder spraying has the following advantages:
- It is possible to provide specific parts or surfaces of the component with a coating
- Complex parts can be coated
- The layer thickness can be adjusted by the amount of layers
- More colors can be selected with this technique
Kersten coating technology is mainly coating pressure bottles and tanks with this process.
With this coating technique the powder in side the spraying-gun is electrically charged. The powder then settles on the metal surface that needs to be coated. Depending on the coating this is applied to a cold or a pre-heated metal surface. With a number of coatings this can be repeated in order to achieve a higher layer thickness.
Some examples of parts that are coated by electrostatic powder spraying:
- Valve houses
- Racks and frames for galvanic processes
The following coatings are suitable for application by means of electrostatic powder spraying:
- Fluoropolymers such as ETFE and PFA Ruby Red
Fluidized bed coating is a process in which preheated parts are immersed in a powder bath. This powder is kept in vortex by blowing air through the porous bottom of the bath. This causes the powder to behave as being a liquid. When the blasted and heated part is subsequently immersed in the whirlpool bath, the powder particles melt down as a solid layer.
Both small and large parts can be provided with a coating using a fluidized bed. Especially pipe sections, couplings and fittings are provided with coatings using this technique. Kersten has options to cover parts with a length of 6 meters and a diameter of approximately 1.5 meters within this process
The following coatings are suitable for application by means of fluidized bed coating:
Fluidized bed coating has the following advantages:
- Specific parts with difficult-to-access surfaces can be coated easily and in a controlled manner.
- In one operation a layer thickness of 400μm is applied, both internally and externally.
- It is an efficient coating method with very low powder loss.
Thermal cleaning is a method of removing old coatings. It is also possible to clean contaminated parts and auxiliary tools that are used in companies that produce coatings. In our pyrolysis furnace parts are heated up to 450 ° C in an oxygen-poor environment. The gases from the pyrolysis are burned in an afterburner at 850 ° C for 2 seconds, after which the gases are cooled and will finally pass through a scrubber. With this installation we can remove old coatings in an environmentally responsible manner.
The floor space of the pyrolysis oven is 6 x 2.5 meters and the height inside the oven is 2.5 meters.
All metals that can withstand a temperature of 450 ° C can be thermally cleaned. On special request we can also carry out separate cleaning charges at lower temperatures.
All coatings applied by Kersten can also be removed by using the pyrolysis oven. It therefore concerns not only Rilsan® and Resicoat®, but also fluoropolymers such as: Halar®, Xylan®, PTFE, FEP, PFA and ETFE. We also remove wet paints and powder coatings from auxiliary tools for other coating companies. Our requirement is that we receive the MSDS (Material Safety Data Sheet) of the relevant product in advance.
The following components are used for dry film lubrication: PTFE, graphite and Molybdenum disulphite (MoS2). These products reduce friction so that no oils and fats are required. These coatings are mainly used in clean rooms.
PPG / Whitford's Xylan® coatings are particularly suitable for these applications. However Xylan® is a large family of coatings with different subgroups and specifications. If you wish to receive further information about these subgroups, please contact us !
An important application for dry film lubrication coatings is the coating of bolts and nuts in the offshore.
Friction creates heat and can lead to wear. Low friction resistance means little heat and less wear. These coatings are used in particular at high temperatures, where conventional oils and fats can no longer be used. Or in the foodbusiness in case products need to slide to or into their next position in the process.
Chemical resistance is the degree to which a coating is resistant to a specific chemical medium. The concentration of chemical substances and the temperature of the medium have a major influence on the level of resistance. We can advise you about the possibilities of our coatings.
The answer to this question is complex and cannot be answered shortly. Each coating has a certain chemical resistance. Per situation we can determine which coating suits best as application. We are happy to advise you on this.
Chemical resistance is important in almost all circumstances. An exception is, for example, a non-stick coating on stainless steel.
The UV resistance of a coating is the degree to which it is resistant to, for example, sunlight.
Rilsan® is a coating that is resistant to sunlight. Halar® and ETFE can also withstand higher doses of sunlight. We suggest to contact us for further advice.
If a coating is used outside it has to be resistant to sunlight. There are situations where UV is used for disinfection of for instance liquids. If coatings are used they have to be resistant to UV in this application.
Abrasion resistance is the degree to which a coating is resistant to wear. It should be noted that certain coatings are more resistant to abrasive wear than others, but no coating will be able to fully prevent abrasive wear.
The plastic coatings are applied in our production in Brummen (NL) or in Kahla (D) using thermal processes. The parts to be coated are heated in indirectly fired ovens, after which the coatings are applied. The coating techniques we mainly apply are:
- Fluidized bed coating
- Electrostatic powder spraying
Some examples of markets that use our plastic coatings are:
- Drinking water market
- Waste, sewage, and cooling water treatment
- Mechanical engineering
- Food industry
- Galvanic and semiconductor industry
- Process and chemical industry
- Automotive industry
Research has shown that thermoplastic coatings in particular are more resistant to wear than epoxy coatings. Thermoplastic coatings are able to withstand the influences of the solid parts much better due to it's flexible nature. Some coatings have a better resistance to wear due to the fact that they can be applied in thicker layers, as there are:
- PFA Ruby Red
With a great diversity in coatings solutions can be offed in the areas of:
- Corrosion protection
- Non-stick solutions
- UV resistance
- Elastic coatings
- Conductive or insulating coatings
- Kiwa and food safety certified coatings
- Wear resistant coatings
- Chemical resistance
Wear resistance is important when liquids or gases are contaminated with solids. Some examples of applications when wear resistance is important:
- Cooling water treatment based on sea water. Especially inside harbors solids are present in water.
- Sewage treatment.
- (Process) Water treatment.
Fluoropolymers are coatings known for their good non-stick properties. In addition to Xylan® and Halar®, Teflon® is also a household name in this field. The name Teflon® is used by it's manufacturer for a large group of fluoropolymers, such as PTFE, FEP, PFA and ETFE.
The food industry in particular uses non-stick coatings. These coatings are resistant to high temperatures and are easy to clean. These properties also come in handy for many other applications.
Fluoropolymers with good non-stick properties are used in processes that are subject to contamination. By using these coatings machines will pollute less quickly and the machines will be easier to clean.
Parts used for production or transport of drinking water must be Kiwa certified. This is applicable for all coatings that are in contact with drinking water during the production process.
The official Kiwa Evaluation Guidelines form a quality system which guarantees the good quality of the coating and the way it will be applied. In addition Kersten is audited several times a year by Kiwa to guarantee the quality.
Kersten has the following Kiwa Evaluation Guidelines, which are necessary for the processing of coatings in the drinking water sector.
- BRL-K746, (application of coating systems for drinking water applications)
- BRL-K759, (coating systems for drinking water applications)
- BRL-K758, (construction guidelines for metal products to be coated)
On request Kersten coating technology provides technical support to select the correct coating. We also advise you on the construction and finishing of the products to be covered. The most important points of attention have been incorporated in our construction guidelines and dimension regulations. We will send them to you on request or you can download them directly.
The vapor density of a coating is the degree to which a coating allows vapor to pass through the coating by influence of diffusion. Due to a high temperature gradient across the coating, vapor penetrates through the coating and will condensate on the metal surface. This causes blisters underneath the coating. To counter this, various fluoropolymers have been developed with additives that increase resistance to vapor diffusion.
The following coatings are available in a vapor-tight version:
- Halar®, ECTFE
- PFA Ruby Red
These coatings are mainly used at higher temperatures and in contact with aggressive chemicals.
These coatings must meet strict requirements in order to be used in contact with food. The coatings are not allowed to release any harmful substances into the food. In Europe the coatings must meet European standards, while in America the coatings must have an FDA approval.
These coatings are mainly used in the pharmaceutical and food industry. The final products of these companies are often exported outside the Netherlands, which means that the coatings used in the production process must comply with European standards.
A coating with an FDA (Food and Drug Administration) approval can be used in contact with food. This approval is mainly requested by US related companies. In Europe there are comparable standards that coatings have to meet.
Several fluoropolymers do have the FDA approval. Some of these coatings are:
- Halar® XPH
These coatings are mainly used in the pharmaceutical and food industry. The final products of these companies are often exported to America, which means that the coatings used in the production processes has to comply with the American FDA.
A Kiwa certified coating is a coating that (in the Netherlands) can be applied to be in contact with drinking water or any substance out of drinking water. These coatings have to meet strict requirements and may only be applied by certified companies on surfaces that meet certain requirements. Kersten coating technology is certified for the application of these coatings as well as for the inspection of the metals to be coated.
The coatings that comply with the strict rules of Kiwa are approved types of the following coatings:
An elastic coating is a plastic coating that does not harden after being applied and is called a thermoplastic. These plastics become soft again when they are heated to their melting point, even after many years.
The main elastic plastic coatings applied by Kersten are:
These elastic coatings can be applied to metal surfaces that deform, such as springs. These coatings are also applied in case high wear is expected. As well, a thermoplastic coating is more resistant to cavitation than a thermoset.
These coatings are applied by fluidized bed coating or electrostatic powder spraying.
An insulating coating will not conduct electrical current. A standard test voltage used to check the insulation tightness of a coating is 9V / μm.
The following insulating coatings are applied by Kersten:
- Various Fluoropolymers
These coatings are mainly applied by fluidized bed coating and electrostatic powder spraying.
Insulating coatings are mainly used as corrosion protection.
A conductive coating is able to conduct electrical current. Therefor these coatings themselves cannot be statically charged and no sparks or discharges can occur.
The main conductive coatings are:
- Halar®. The black version is not only conductive, it also protects metals against a variety of chemicals. Due to the FDA approval this coating can also be used in the pharmaceutical or food industry. The non-stick properties of this coating are also good.
- Xylan®. In addition to a conductive surface this relatively thin coating also offers a surface with very good non-stick properties.
Conductive coatings are used in EX environments. In such environments sparks can cause a reaction or explosion.
Some examples of metals that can be provided with a plastic coating:
- Carbon steel
- Stainless steel
- Cast iron
Our coatings are applied using thermal processes. For the application of the various coatings it is necessary to heat the metals. This can be done before or after applying the coatings.
Corrosion is damage to a (metal) surface due to various influences. The rusting of steel is the best known type of corrosion. However other metals, such as stainless steel, can also corrode.
By protecting metals against corrosion their lifetime can be extended and costs can be saved. Our fluoropolymers also ensure that in addition to corrosion protection, the surfaces will be more easy to clean due to the non-stick properties.
Corrosion protection of metals is necessary in many different circumstances. Some examples of sectors in which our coatings are applied as corrosion protection:
- Drinking water
- Cooling water
- Ultra-pure water
- Strong acids and bases, even at high temperatures
- Swimming pool water
- Waste and sewage water
- Process water
By providing metals with a protective layer as with coatings, corrosion can be prevented. The plastic coatings that Kersten uses for corrosion projection are:
- Variety of Fluoropolymers
Kersten has applied plastic coatings to metals since 1967. Initially from Eerbeek, but a few years later Kersten moved to Brummen. In 1995 a second location was started up in the East of Germany, Kahla in Thüringen.
Depending on the type of coating and the number of parts to be coated, the delivery time is between 1 or 2 working weeks. Please contact our team if you want to make special arrangements. We always want to think along with our customer.
Kersten applies plastic coatings using thermal processes. The main coatings are:
- Rilsan®, biobased nylon 11
- Resicoat®, epoxy
- Halar®, Fluoropolymer ECTFE
- Xylan®, Fluoropolymers, PTFE, FEP and PFA
- Other fluoropolymers including, ETFE
- Abcite®, thermoplastic