Removal of Weld Balls and other Contaminants from Industrial Paint Pre-Treatment Wash and Rinse Solutions

Paint finish quality is a critical aspect for many products including automobiles, heavy equipment, trucks, buses, office furniture, electrical enclosures, lighting fixtures and many other products.  Defects and/or blemishes in the paint finish can be very costly to the manufacturer.

Prior to painting, these metal products are formed and/or welded.  Metal fines, metal slivers, weld slag and weld balls, as well as oil, grease and weld flux are by-products of the fabrication process.  These contaminants must be removed from the metal surface prior to painting, and ideally most contaminants should be removed prior to application of the corrosion protection substrate (i.e. zinc phosphate, iron phosphate, zirconium phosphate, etc.).   If the contaminants are not effectively removed from the process, they will redeposit on the component and render the entire cleaning process ineffective.

The paint pre-treatment process includes multiple cleaning/degreasing stages, rinse stages, conditioning and conversion coating stages.  Each stage requires filtration to remove contaminants. 

Historically, industry has relied on bag filtration, cartridge filtration, roll media, centrifugal separators, hydro-cyclones, and continuous overflow of process fluids to remove the contaminants that can cause defects.

  • Centrifugal and cyclonic technologies do not consistently remove small particles.  
  • Roll media is inconsistent and often subjected to by-pass conditions. 
  • Continuous overflow is costly and increases the environmental impact of the process.
  • Bag filtration is the most widely utilized filtration technology throughout paint pre-treatment systems.  However, problems associated with bag technology include: 
    • Extremely labor intensive → Labor associated with changing bags increases operating and maintenance costs and consumes manpower that could be utilized for more value-added plant services.
    • Inconsistent and unreliable → Bag filters are nominally rated so the effective filtration can vary by supplier, and even by batch.
    • Premature “blind off” → When this occurs, the useful life expectancy of the bag is significantly reduced. 
    • Easily circumvented at the operator level → If bag filters require change out too frequently, then the micron rating is typically increased to reduce change out frequency; or the bags are permanently removed from the housings.

The changing of bag filters can be the single biggest source of contamination in the paint shop. The bags may remove the contaminant: but the contaminant gets re-introduced during the change out.

ZGF technology removes contaminants effectively and efficiently

Cleanliness is critical, and poor cleanliness is costly.  Dirty surfaces can have short-term (re-work) and long-term (warranty, poor consumer quality scores) cost implications.

It is essential for the cleaning equipment to remove the contaminant from all surfaces of the components.  But it is equally important to ensure that all the contaminants are effectively removed from the wash / rinse solutions.  Even if the cleaning technology (i.e. spray stage, immersion stage, etc.) effectively removes the contaminant from the component, if the contaminants are not effectively removed from the process (i.e. the wash solution), they will redeposit on the component and render the entire cleaning process ineffective. 

Typically, it is not the big contaminants that cause the problems.  They are easily removed.  The particles that are 75 micron and smaller are of greatest concern.  Some of these particles you can’t even see!  The human eye can’t see particles smaller than 40 micron.  Click on the Particle Size Chart to better understand the size of common things and how clean components must be prior to phosphate and ultimately paint.

ZGF Maggie technology can provide value in every stage of the pre-treatment system.  Maggie technology is a contaminant specific technology.  It is designed to remove the metal fines, metal slivers, weld slag, weld splatter and weld balls (i.e. ferrous materials) that are introduced into the paint shop from the pre-finishing/fabrication operations.  Although ZGF Maggie technology is not designed to remove non-ferrous contaminants such as sealer, abrasive material, etc., introduction of those contaminants will not damage or negatively impact Maggie performance; and Maggie will capture/trap some of these contaminants. 

ZGF Spring Filter technology is ideal for the rinse stages.  It is a fully automatic, permanent media solution.  There is no disposable media, virtually no maintenance, and minimal operating expenses.

ZGF Maggie and Spring Filter technologies effectively and efficiently capture and remove contaminants from the paint pre-treatment system, reduce defects, improves finish quality, reduces total operating cost and the overall environmental impact of the process.  ZGF Maggie and Spring Filter technologies will provide value throughout the paint pre-treatment system. 

ZGF technology is:

  • fully automatic
  • consistent & reliable
  • non-disposable
  • energy efficient - utilizing a minimal amount of electricity and air during purge/backwash
  • able to remove ferrous particles down to 1 micron and non-ferrous particles down to 20 micron
  • able to reduce defects per unit, fluid usage, and labor while improving quality
  • able to provide value throughout the pre-treatment system and help optimize each process by effective and efficient contaminant removal


ZGF technology can be installed in a variety of places in your process.

ZGF Maggie and Spring Filter technologies are often implemented in Industrial Paint Pretreatment systems

To get a better understanding on where ZGF Maggie and Spring Filter technology can provide value in your Paint Pretreatment Operations, click here to download the Process Diagram, Paint Pretreatment

If you want to learn more about ZGF Maggie technology,

then download the Maggie Product Data Sheet or view the Maggie in action by watching the Maggie video.

If you want to learn more about ZGF EZ Clean technology, then download the Phoenix Product Data Sheet or the EZ Clean EZ700S Product Data Sheet or view the Spring Filter video and see how all the contaminants are removed during backwash when the filter element opens and shimmers.

ZGF technology provides cost, quality and environmental benefits in your paint pretreatment operations.

  • improved part finish quality (decreased defects per vehicle)
  • better process reliability
  • no consumables and virtually no filter maintenance
  • fully automatic, 24/7 operation
  • lower total operating cost

ZGF technology provides value

ZGF technology is a global standard and has been adopted as the best available technology for removal of metal fines, metal slivers, weld slag, weld splatter and weld balls (i.e. ferrous materials) from the paint pre-treatment stages within several automotive manufacturers.  As they continue to implement our technology and realize the exceptional value, some organizations have shared their success stories. 

Click on Success Stories to jump to the Success Stories / Case Studies page to learn how ZGF technology provides value.  Click on the links below to learn how our customers were able to reduce operating costs, improve process reliability and quality, and reduce the environmental footprint of their operations by implementing ZGF technology in the paint pretreatment system.

Simplicity, consistency, reliability and the lowest cost of ownership make ZGF technology the best solution and value for your paint pretreatment operations!

ZGF is your preferred partner.

 Filtration should not be a burden.

 Filtration should be a tool that improves quality and reduces cost.

Let us help you meet your objectives and make your job easier!


 ZGF has the experience and dedication to customer satisfaction that you are looking for. Contact us or request a quote today.