What is powder coating?
Powder coating is the use of a dry ground polymer resin that is electrostatically sprayed on to a material that is then ‘baked’ or cured in a large oven.
How long does it last and is it worth the cost?
When compared to buying a brush, a tin of Hammerite and wasting a free Saturday, maybe not. Where it really comes into its own is the lack of maintenance. In our experience, after several years the only damage is colour fade; you can view a prime example by taking a look at this bridge we did (5 years between install and photograph).
Is it worth hot dipped galvanising with a powder coated top coat?
To me, it is an unnecessary expense. Very often the 2 processes are carried out by different companies at 2 different locations. Even if that is not the case the steel requires fettling (taking off the sharp pieces of zinc) which can be time consuming to achieve a high finish. The answer here, in most cases, is to use a powder coated zinc primer. Click here to learn more about hot dipped galvanising.
Is a zinc rich primer as good as galvanising?
For longevity, the simple answer is no. However it is much cheaper when apply a top coat later as the primer doesn't require fettling or degassing, is less likely to have a reaction with the top coat (we've seen bad cases of bubbling before) and both coats will be done at the same premises.
What is fettling?
Fettling is required to remove the sharp zinc pieces created in the hot dipped galvanising process. This is generally done using soft sanding pads attached to power drills or angle grinders and, for the more delicate jobs, hand files and sandpaper can be used.