I often hear, what is sand blasting and why should I get it done on my parts? Sand blasting is one of the main ways to ensure that the powder coating process not only goes as smooth as possible, but also ensures that the final product stays strong and endures the elements and the test of time. Powder needs a surface profile in order to properly adhere. If you have ever bought cheaper powder coated fencing at hardware stores, and the powder chips off in strips or sheets, it probably was not properly prepped. Although sandblasting adds more upfront cost, it ensures that the powder properly adheres to the metal, saving you from major problems down the road.
Sandblasting is the most common form of media blasting, you are essentially using compressed air and sand to strip the metals clean and give it the profile the powder needs to stick. If you have ever used sandpaper, it is essentially the same idea. Although sand is the most common, everything from glass, to steel and walnut shells are used for all kinds of different substrates. Everything from wood to glass and plastic can be media blasted, depending on what media you use.
When looking for powder coating near you, be sure to consider several different factors when deciding what kind of prep you are needing on your parts. Have they been previously painted or rusting? Probably want to find someone who can sandblast. In my opinion pieces that get sand blasted have the highest chance of success and turn out the best looking products. If you are dealing with a piece that has been previously painted or coated, you never know how well that piece was prepped. When we first started, we realized pretty fast that sandblasting to bare metal is the best solution, too many times we ran into situations where the old powder was poorly applied, making the top coat fail just as fast as the bottom coat failed. Especially with projects that are going to be exposed to harsh elements like salt water and snow, you need to be 100% sure that the product is properly prepared and the powder will hold. The quality of the powder coating job is only as good as the preparation that was done before the powder is applied.
This same concept works the same if your powder coating, or painting the substrate, especially with paint since it tends to show more imperfections than powder. With powder you have the advantage of some powders covering up imperfections more (thermoplastics for example are shot very thick and can cover up grind marks or bad looking welds.) No matter if we are painting or coating a piece, we always blast it if we can, it is one of the best ways we can ensure that our finish will goes on smooth the first time and look great every time.
Within the last few years the popularity and efficiency of automated powder lines has skyrocketed, with that blasting is often replaced with a chemical process that “etches” the metal giving it the profile needed by powder. While this is a great and sometimes easier way to prepare metal for powder, there are problems and situations where this just doesn’t work. Unless your product is fresh metal, blasting is the only way to ensure all the oils, previous coatings, or rust is removed. For smaller shops it is also difficult to constantly ensure your chemical levels are exactly where they need to be in order for the etching process to work. If you can get the system and flow down for chemical etching, it can extremely speed up the efficiency and turnaround times of a shop. Since substrates like most aluminum and thin sheet metal cannot be sandblasted, the only other option is the prep the pieces by hand which can eat up a lot of time and man powder.
With so many different material options, blasting can be done on tons of different substrates. It is very popular for restoring older car parts that have been damaged by rust and time. Old lawn furniture is also very popular for blasting, years of use and layers of paint or powder can be impossible to remove without blasting. A form a blasting called soda blasting, using sodium bicarbonate or baking soda to restore and clean objects that are too fragile for media blasting. One of the early examples of soda blasting is in 1980 when it was used to restore the Statue of Liberty. A great benefit to soda blasting is it's ability to be mobile, allowing for a vast array of options. Everything from graffiti removal to cleaning boats and satelite dishes.
We have gone over some of the things that blasting is great for, but its not the best solution for everything. If your product is made of very thin metal or sheet metal than blasting may not be the best solution. If the substrate is thin, the heat generated from sandblasting, as well as high air pressure, is enough to warp and possibly destroy what you're working with. Aluminum is also a tricky substrate to blast, depending on how thick it is, it can be warped in the blasting process as well. In these situations, having a way to chemically clean your parts is essential to making sure the powder sticks as well as it needs to.
We sometimes get asked if we can blast wood and if it is a good idea or not. Blasting wood is an entirely different ball game when compared to blasting metals. It all depends on the skill of the person blasting and knowing the right pressure, media, etc to use. We have very rarely blasted wood, and it has been mostly for wood signs. Blasting can give wood a really great look once stained, however it is a scary process considering wood can be very easily damaged. If you are looking for wood blasting, be sure to ask a lot of questions before handing over your work to someone.
If you are bringing something that you think might be a bit more fragile, make sure to discuss with your local coater the process they go through, and see if he or she has done what your bringing to them before. If you are getting wheels redone and they don’t usually work on wheels, it might be a good idea to shop around and find someone who does them more often. The blasting process can irreversibly damage wheels if not done properly, using steel shot for example on aluminum wheels is going to end badly.
Once broken down, walnut shells can be used as well.
This may seem like a lot of work, but in the end of the day you want your product or customers work, to be the best and highest quality it can be. Skipping this step is tempting to save money and time, but more often than not it ends up ruining the finish years down the road. The only way to successfully do that is to take out as many variables as possible for failure, sandblasting is the best way to ensure that the powder will come out looking beautiful and do its job for years and years.
Great substrates to have blasted
- Old metal furniture
- restoring car parts
- Off road vehicle parts
- Copper parts can be blasted lightly
- Playground equipment
- Thick aluminum
- Vacuum sealed drinking cups
Substrates to stay away from with blasting
- Thin Sheetmetal
- Thin Aluminum
- Wood ( Wood can be blasted but it is very difficult, consult your blasting company before you bring them wood. It can be permanently destroyed very easily. When done right however it can be very beautiful. Ask about Soda blasting if you need wood done.)
- Plastics can be media blasted, like wood however it can be very difficult and there's no going back after its done.