How to seal the structure before powder coating?
Powder coating is a popular way to cover metal elements with paint. In order to obtain a satisfactory effect, the structure must be properly protected and sealed before powder coating. How to do it?
Powder painting, as the name suggests - uses paint in the form of powder in this process. Using this form, it is possible to paint metal elements. It is applied with a gun that electrifies paint particles, making it easier to attach to metal elements. The whole thing is done dry without solvents or water. The applied coating is bound and hardened in a specially adapted heating furnace , in which the temperature is up to 200 degrees.
Structures and elements painted in this way are characterized by:
- high durability
- resistance to abrasion, chemicals and weather conditions
- very good corrosion protection
- the whole is distinguished by an elegant and aesthetic finish
Often, powder-coated structures must be sealed or glued. However, most adhesives and sealants have a temperature resistance of up to max. about 90 degrees and after placing them in the oven where the temperature will be more than twice as much, unfortunately the joint may break the bond and the material will simply dissolve. This is where innovative thermosetting sealants come to the rescue. A product of this type was released some time ago by Sika. We are talking specifically about Sika Power 415 P1 sealant. It is a one-component black preparation. Packaging in the form of a 400g cartridge, can be applied with a standard silicone gun.
Preparation of the structure before powder coating
Preparation of elements before powder coating and their sealing is similar to other surfaces to be painted or bonded. First of all, clean the place of tarnish and dust. The whole can be mechanically cleaned and sanded. Especially if there is a rust coating on the element. Then it will be very important to remove all types of greasy dirt, oil, silicone from the surface . Solvents can be used for this, which in most cases will cope with dirt. Sika Aktivator 205 would also be useful here, it will perfectly remove stubborn dirt and prepare the surface for bonding, activating it and increasing adhesion at the same time.
In the case of powder coating, sterile conditions are required, which is why the entire process of applying powder paint takes place in specially adapted powder booths , and the employees themselves perform the entire process in overalls. The powder coating room will guarantee that no unwanted dust and dust will get on the surfaces. On the market you can find automatic booths that allow you to shorten the time of painting and the involvement of employees in this process, because the whole thing is done for us by the machine.
Sealing the structure before powder painting
Elements subjected to powder coating may require sealing, e.g. joining discontinuous welds, sheet metal joints. As we mentioned, you will need to use a thermosetting material specially adapted to this process. In this case it is possible to use Sikapower 415 and then paint the structure. The sealant will cure as the components heat up. After such treatment, the sealant will perform the same function as standard adhesive masses, and the strength of the joint may be higher.
How to seal the structure before powder coating
Sealing the structure with a thermosetting sealant is similar to a regular sealant. Sikapower 415 P1 comes in an aluminum cartridge like most adhesives, sealants, etc. It can be easily dispensed with a hand-held skeleton gun . In the case of larger powder coating works, the use of Siki pneumatic squeezers will certainly be helpful, which will not only improve the work, speed it up and increase the comfort of application, but also allow for a more even weld.
It is also worth mentioning the product SikaPower 4508 , like 415, it is thermosetting and has very similar technical parameters. It is also used as a sealant before powder coating. The main difference between the two is that Sikapower 4508 is white in color and comes in a 400ml film capacity. To squeeze out such material, we will need a tube gun , which allows you to squeeze the materials in the foil. In this case, Sika also has a solution to apply such a product with a pneumatic film extruder.
If we are talking about the industrial application of sealants, Sika also has these materials in a capacity of 23L, the so-called hobbocks or large barrels - 195L . Then the sealant is applied using special pumps that allow the material to be applied.
Regardless of which method and sealant we choose, we must ensure that the final joint is even and smooth if we care about aesthetics.
The applied sealant must, of course, be protected against all kinds of dust and dirt until it hardens, because the fresh spin can easily attract dirt before we heat it in the oven.
The application of such materials should not cause major problems if someone had to deal with, for example, the application of ordinary silicone. It is known that practice makes perfect, which is why, over time, the sealed elements may start to look like from the factory.
Sealant for powder coating
At the moment, the use of materials such as the aforementioned Sikapower 415 P1 and Sikapower 4508 is the best solution for sealing elements before powder coating. Ordinary sealants based on polyurethane or MS polymer will not cope with heating at high temperatures, which is why the use of a thermosetting material is necessary here.
Ease of application and strength parameters after hardening will also speak in favor of its use. At the moment, there are very few products of this type on the market, which is why Sika can boast of a specialized material for joining and sealing metal elements before powder coating.
1. What product should be used to seal the metal structure before powder coating?
The sealant that should be used to seal the metal parts before they are powder coated is a thermosetting adhesive. Sika's Sikapower 415 P1 material can be such a product.
2. What is the cost of thermosetting sealants?
The cost of a thermosetting sealant for powder coating for application with a hand gun is about PLN 120-150 .
3. How does Sikapower thermoset metal sealant cure?
Thermosetting products intended for gluing structures before painting the structure will fully harden only in the heating oven, which is used to harden the powder paint.