Plastisol vs. powder coating

A. Powder coat and plastisol are very different. Powder coat is an electrostatic paint spray process. The details for this process can be found in the Organic Metal Finishing Guidebook put out by Metal Finishing Magazine.

Plastisol is a very thick coating of plastic applied by dipping a part into a liquid solution. Plastisol is used on bare tools (wrenches, pliers, etc.) to give it a nicer grip area. It is also used to coat plating racks to prevent the rack from picking up plating each time is goes through the plating tank.

Powder coat is much cheaper, and I imagine that this is what your customers are looking for. Plastisol is only used for more specialized applications when a thick non-conductive plastic coating is desired.

A. Generally, these topcoats are a thick tough surface finish with a flexible system and good adhesion. They are applied through dip molding, Plastisol bed coating and fluidized bed coating. They can be custom compounds to achieve hardness, flexibility, color, surface appearance, abrasion resistance, flame retardation, insulation and other desired characteristics to meet customer specifications. These compounds plastisols (PVC) can be designed for a wide variety of industrial and commercial applications serving the medical, toy, leisure, recreational, construction, textile, and automotive markets including:

Plastic coated
Handle grips
End caps
Hose protectors
Garlic peelers
Trailer ball covers
Diving tank protectors

To apply a PVC type coating, the metal part or rack that will be coated must be physically clean prior to application of the primer and plastisol. (PVC's generally require a primer before topcoat application but can also be applied with powder equipment).

Dip, spray or brush primer onto the metal part making sure the area that will receive the plastisol is covered with the primer. Place the part into an oven that has been preheated to 350-375 °F. The primer is cured when the metal part reaches 350 °F. The time for this occurs depends upon the mass of the metal part, the efficiency of the oven and other factors. Remove the heated part from the oven and immerse it into the liquid plastisol. Slowly withdraw the part moving it sideways very slowly to make sure the desired area is covered. The thickness of the coating will depend upon the mass of the metal part and the rate of withdrawal rate. Allow the part to drip so as to minimize any "tear drops."

Place the coated part into a preheated 350-370 °F oven and bake until the internal temperature of the plastisol reaches 350 °F. Baking time will vary depending upon the size and mass of the part as well as the efficiency of the oven. One indicator that the plastisol has cured is that the coating will become glossy in color.

Also please note that many company's use molten salt as a cure for their PVC lines and in a dip system. The primers are then generally a water-based primer.

Plastisols are measured using a Durometer. Some of the coatings carry vinyl dispersion containing MEK and MIBK. PVC carries Plastisol, vinyl and nylon materials and are usually developed for ultra thickness and durability.

Powder coats on the other hand are generally developed for less physical type durability and more cosmetic appeal, especially with thermo-setting topcoats. Thermoplastics are generally designed for more frictionless type functions and do not see the thickness that PVC can acquire.

Bob Utech Benson, Minnesota

Ed. note: Bob is the author of: "High Performance powder Coating" on eBay or AbeBooks or Amazon [affil links]

I think you have not answering correctly about "plastisol coating". In fact "plastisol coating" has very little to do with "dipping" but mainly to "knife coating" to produce synthetic leather. If you want to know more please don't hesitate.

Regards,

Often a term can have more than one meaning, which is apparently the case with 'plastisol coating', Mr. Carlino.

But the previous responders are correct that, in their context at least, plastisol coating involves dipping the object (usually metal) into a hot tank containing liquid, plasticized, polyvinyl chloride. This is widely used as a tank lining, a coating for electroplating racks, a corrosion resistant coating for steel parts that will be exposed to acids, insulating grips for tools, etc. The term has been widely used by thousands of people in the plating industry for over 50 years, including in published journals and textbooks.

Thanks for letting us know the term is also used in the manufacture of vinyl artificial leather cloth :-)
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

A. When adhesion is concerned on metal parts, either steel, aluminum or alloys, every coating process have a suitable pretreatment on the metal parts. Regarding adhesion for plastisol coating, there is a waterbase phosphating conversion compound which is able to withstand high temperature about 280 °C prior to plastisol coating. It is supplied to the outdoor playground industries.

A. Plastisol is a simple solution of PVC in plasticizer.
Additive like heat stabilizers and antioxidants are normally added. Colouration is done immediately before applying.
Plastisol can be "coated", "sprayed", by brush, deep coated, printed (textile screen printing).
Best way to produce it is asking to PVC supplier for a right "K" value depending on article/performance to be obtained.
Normally plastisol are available on the market "ready to use"...
Good Luck

A. Dear Sir,
The plastisol products based on PVC powders in addition of plasticizer as a solution for PVC. The application of Plastisol coating, as we know, utilized on the Automotive manufacturers, specifically in paint shops and in purpose of dampening, anti-corrosion, sealing the hemmings, under body coatings, and .... Either we can consider the plastisol coating as a non-newtonian fluid which shall be controlled after production by Rheology instrument to determine the Viscosity and yield point.
Sincere salutation

A. Hi Ejaz.

Yes, plastisol is liquid PVC. After it dries/cures it leaves a thick, soft, PVC coating similar to a soft PVC lining material. I believe that coatings from 30 to 90 mils are customary. Thinner coatings can be sprayed; thicker coatings are dipped. There are air-dry plastisols, but I believe that the solvent based baked coatings are better.

A common application is the insulating coatings on plating racks. It is sometimes applied to the handles of tools like pliers.

Regards,

A. Hi Jamie. Plastisol would probably work as a masking material, and you could probably remove it with a strong solvent; and certainly by burning it off. But ...

There are lots of masking materials that would be better, including "plater's tape" which is quite similar to electrician's tape, only heavier and usually colored. For a one-off "playing around" you might even try a couple of layers of electrician's tape. Otherwise there are maskants specifically for the purpose.

Regards,

A. Hi Mike. I strongly doubt it. I have seen powder coating used as a maskant for plating on a "once thru" process (the parts were powder coated in some areas, then plated where there was no powder coating). It was robust enough for one pass through the plating cycle with a fairly low reject rate, but hard anodizing involves higher voltages (48 V? 75 V?) than plating, and you obviously want it to survive hundreds of cycles or more.

Regards,

A. Hi Luca. I doubt that any other finish matches PVDF for long term exterior application. But a problem already evident in this thread is that 'plastisol' may mean different things to different people.

To we from the plating industry it means a very thick (0.030" and up, even 0.090") soft and shiny vinyl coating. Without a specification of exactly what is meant by the steel panel supplier -- pretreatment, thickness, application method, composition -- it is anyone's guess :-(

Regards,