Is it Possible to Powder Coat Chrome?
Here at Maldon Shot Blasting we would like to put the record straight.
Powder coating is a process commonly used to coat parts of all kinds and protect them from corrosion and rust. The process involves applying a coating over a metal surface by blowing a dry powder onto the surface and then curing by heat until it forms a protective long lasting layer over the surface.
It is often used in the automotive (especially with motorcycles) industry, but one question many people ask is whether it’s possible to powder coat chrome. After all, the spray-on powder does need a good clean and etched surface it can adhere to and chrome being chrome is inherently a very smooth surface.
Here are some things to keep in mind if you are considering having a powder coat put on chrome parts:
First and foremost, it’s important to realise that you can’t powder coat over chrome and expect a good long term quality finish without the correct prep work.
Powder coating will not adhere to untreated chrome. In order to carry out the work properly,the surface must be striped of chrome and then apply the powder coating be it by having it removed by a chrome plating company or in the case of low grade cheap chrome can be removed by blast cleaning. Heavy chrome (as Harley) can be etched by blast cleaning but there is a risk of breaking through the surface and leaving ridges that can and often will leave you with little choice to carry on although not recommended, the safest is to again is to have the chrome removed by a chrome plate company.
For a professional finish we highly recomend this to be removed by a chrome plater.
It is possible to use a powder coating that looks like chrome after it has been applied. This type of coating generally cures with a very reflective surface that looks similar to chrome, although technically, it isn’t chrome at all.
Maldon Shot Blasting stock high quality chrome effect powder and it is extremely reflective without a lacquer coat, this is fine if you want to keep your items indoors away from sunlight and general pollutants, as the chrome effect powder is NOT UV stable and will fade, therefore a good quality diamond clear lacquer coat must be applied rendering the chrome coat down to a very bright silver.
Before the powder coating can be applied, the parts must be blast cleaned so that any residue that’s on them removed. However there are some chrome that just will not budge by blasting, typicality you will find that when you break through the plating (on heavy chrome you may damage the base metal whilst trying to remove what remains.
Pretreatment is an essential part of powder coating because it ensures that the parts are completely clean before the powder coating is applied. It is easy to tell parts that have not been pretreated and / or blasted before the coating was applied because that coating starts to flake off not long after it is applied.
Be sure to ask several questions of the shop you are planning on using to apply the powder coating because not everyone applies coating to the highest quality standards. Pretreatment is necessary if you don’t want the coating to flack off.
Also keep in mind that while some chrome parts can be powder coated after careful pretreatment , there are some that it is advisable not to coat. Chrome itself is usually applied by lower temperature plating, and if the part itself cannot stand up to temperatures of around 350 degrees Fahrenheit, they should not be powder coated. High temperatures are necessary in order to get the coating to adhere to the surface successfully. In some cases you may be able to protect sensitive areas on each part by masking off with high temp products designed for the purpose, but as always, check with a professional how the work will be carried out.
If the company you use tells you it can be done then buyer beware of the downfalls.
Other points worth considering
If the chrome is of poor quality and thinly plated then is easily removed by blast cleaning.
In many cases rust can sit under the chrome plate eating through the chrome and also into the substrate leaving behind deep pitting.
Chrome can be damaged by the high heat process for powder coat curing.
Reading through some of the blogs on this subject written by so called experts (home coaters in the main) I came across one that said “ providing the chrome is clean you can powder coat over it) wrong on every level.
In most cases we offer our five year anti corrosion warranty but keep in mind we have to consider the long term results on certain items that are badly corroded, as we can’t make a silk purse from a sow’s ear, even with the very best intentions
Because powder coating does not have a liquid carrier, it can produce thicker coatings than conventional liquid coatings without running or sagging, and powder coating produces minimal appearance differences between horizontally coated surfaces and vertically coated surfaces. Because no carrier fluid evaporates away, the coating process emits few volatile organic compounds (VOC). Finally, several powder colors can be applied before curing them all together, allowing color blending and bleed special effects in a single layer.
While it is relatively easy to apply thick coatings which cure to smooth, texture-free coating, it is not as easy to apply smooth thin films. As the film thickness is reduced, the film becomes more and more orange peeled in texture due to the particle size and glass transition temperature (Tg) of the powder.
Most powder coatings have a particle size in the range of 30 to 50 μ (Microns), a softening temperature Tg around 80 °C, a melting temperature around 150 °C, and are cured at around 200 °C. for minimum 10 minutes to 15 minutes (exact temperatures and times may depend on the thickness of the item being coated). For such powder coatings, film build-ups of greater than 50 μ (Microns) may be required to obtain an acceptably smooth film. The surface texture which is considered desirable or acceptable depends on the end product.
There are very specialized operations where powder coatings of less than 30 micrometres or with a Tg below 40 °C are used in order to produce smooth thin films normally reserved for special candy coats & diamond clear lacquer coats.
Engine Powder Coating
A lot of clients ask if you can powder coat a complete engine; so for your information an explanation is given below.
It’s not that straight forward to powder coat a complete engine in-fact it’s disastrous.
Why?. The preparation work for powder coating, requires at the very least bead or aqua blasting so as to clean and etch the surface (allowing a good surface for the coating to adhere to) this can and probably will lead to ingress of unwanted blast media into the engine. This is not a good situation for your engine, it will almost certainly cause damage, as this process is carried out using high pressure compressed air at 4 to 8 bar.
Fine glass bead media is used during the cleaning and etching process and this type of medium is the very stuff that can find it’s way into vital oilways thus cutting oil flow and of course grinding away at all the moving parts, leading to the possibility of the engine seizing.
So what to do!.
Strip the engine apart. This is the safest and most effective way to achieve a really good job.
If you do by chance find someone willing to powder coat a complete engine, please think long and hard as you may well regret your decision.
If you feel it’s beyond your technical skills to strip the engine and gear box, we can help you with this process by arranging to have this work carried out by our bike mechanic. Costs for this service however will vary according to engine type and any replacement or service parts required on rebuild.
Acid Dipping / Caustic Dipping/ Soda blasting -V-Plastic or conventional media blasting
“FOR THE REASONS EXPLAINED BELOW WE DO NOT CARRY OUT OR RECOMMEND ACID DIPPING”
A common and very cost effective way of stripping paint and coatings from ferrous and non-ferrous components is to acid or caustic dipping. However, although recognised as an inexpensive way of conducting this process, stripping of items such as a car body can give rise to numerous negative effects. The use of these aggressive chemical strippers can, for example, leave residual chemicals entrapped in the frames, joints and structure of a car, vehicle body or panel.
Additionally the inside of the vehicle body and panel will have been paint dipped by the manufacturer and this will then be removed by the acid/caustic stripper and cannot be replaced, leaving the inside of the body shell/panel open to possible corrosion from within.
Plastic media stripping,
as an alternative process, only strips visible areas on a selective basis. Ideally suited not only to paint removal from steel and aluminium bodies, it will also work perfectly on composite and glass fibre vehicles and panels, with no fear of component distortion, which can occur with conventional blasting.
Unlike chemical strippers, plastic media is non-toxic and non-polluting and the process was accepted as the ideal method of achieving delicate surface preparation for a wide variety of materials and components
Often thought of as the answer to a variety of expendable and coating removal process needs, soda or bicarbonate of soda blasting is centered on a highly caustic product – indeed, it should be noted that, in certain circumstances, it can cause a reaction to an operative’s skin and is difficult to ‘wash away’ when used outside. It should be swept up or vacuumed away as attempting to wash away into drains can often cause blockages.
Not effective for removing rust or heavy contamination.
Additionally, using soda to blast paint from automotive and aerospace coatings means that a residue of the removed coating will be mixed with the used soda and there will also be a portion of soda (caustic) entrapped in seams and rivets. When this retained material becomes wet it will react and damage any coating that has been applied. Therefore, such components need to be thoroughly washed to remove any residue.
Powder Coating preparation and removal
The requirement for an optimum finish in a powder coating starts with an ideal surface profile. Whether it is removing manufacturing imperfections or creating an even profile across a component, blasting is often the best way to achieve this economically and efficiently.
On ferrous substrates, the use of a cast iron/chilled iron media or of hardened steel grit is often preferable, while on a non-ferrous component, invariably is ideal. Removal of powder coating when manufacturing errors occur can usually mean a laborious process to remove these tenacious coatings. With the advent of plastic media stripping , this process has become significantly easier than with conventional blast materials. Due to its low heat generation and aggressive angular cutting ability, plastic media can remove powder coating faster than any other media.
Without this process it will be inevitable that the final finish will not give a long lasting and satisfactory finish. This is one of the reasons we offer a five year warranty on most of our powder coating work.
By utilising a small glass entrapped in a special clear powder coat, a prism is created, and when light is shone directly at a coating containing the bead a vibrant reflection of the light bounces back at the origin. This captures the concept of a cat’s eye , which is relevant to most reflective materials such as highway white lines and clothing reflective strips. We supply a diverse range of glass beads for highway and reflective applications from BS6088 approved products to customer bespoke blends of high refractive index beads.
Our Opening Times:
Monday to Friday: 9.00am – 5.00pm
Saturday: 9.30am – 12.00pm
Closed Bank Holiday weekends
Tel: 01621 841100
Fax: 01621 842233
Unit 2a, Benbridge Industrial Estate,
Heybridge, Maldon, Essex,