Silicon-free

During the last few years, our company found a not-too-insignificant number of manufactures of synthetic resins, varnishes and other coating material. These manufacturers include also paint-shops and their involved enterprises. We achieved remarkable success through installations, apparatus, components and services supplied by us, because we are aware that we can offer our customers products of the highest standard only through accurate planning in engineering, use of high-quality material, efficient storage, trouble-free production processes, and detailed final assembly in order to ensure reliable acceptance and commissioning of a plant.Despite extreme care, customers sometimes face problems with the surface characteristics of varnish coats with the result that end users in the paint shop have a tough time. Unfortunately, the cause of contamination lies with the possibilities within the long chain of involved enterprises much before the paint shop. In this respect, PURPLAN wishes to assure its customers as part of our service that we have done everything to the best of our knowledge so as to prevent such contaminating substances from sneaking into your production processes and thus affect the installations or components supplied by us. In this respect, we endeavour to be constantly in touch with you which would be beneficial mutually.

How does contamination happen?

High-molecular polydimethylsiloxanes (PDMS, or known simply as "silicones"), and sloughage from synthetic materials (e.g. polyethylene, polytetrafluorethylene) and high-molecular polyglycols can cause severe surface deterioration even with the least contamination of our products when these are used in paint shops. Cross-linked silicones (e.g. silicon rubber) are by themselves harmless. But most silicon rubber products contain enriched high-molecular silicon oils as softeners. Therefore, it is advisable to conduct investigations and to consult manufacturers in every situation.
Such substances are highly incompatible with varnishes and they cause surface deterioration (sinkholes) in the varnish coating.
We can hardly imagine how particularly high-molecular polydimethylsiloxanes propagate in our working and living environs.
In the following, we present some of the known applications where high-molecular polydimethylsiloxanes are used:

• Lubricants
• Deep-drawing accessories
• Personal care products of all kinds
• Anti-rusting impregnations
• Skin-care products
• Cleaning agents
• Sprays of all kinds
• Sealing rings for face seals
• Sewing thread for filtering material
• Seals
• O-rings
• Sealing compounds
• Lubricants in fittings such as ball cocks, valves etc.
• Counter-pressure fluid for face seals in pumps and stirrers, in manometers etc.
• Hose pipes
• In container material of sheet metal and synthetic material packaging
• Lubricants in cam-lock valves of IBC
• In screw caps of sampling bottles
• Malfunctions in container fixtures despite cleaning as per normal procedures

The list is in no way complete. In many cases, high-molecular polydimethylsiloxanes are only a small additive to obtain a particular effect. Unfortunately, these are often not even declared as ingredients.
We are keen to receive more information also from you about products possessing such properties that should be taken note of while fending intrusion of contaminating substances in varnish material.

This problem is constantly addressed in the paint manufacturing industry and its chain of suppliers. It is quite likely that more contaminating substances are identified. We, too, continue to cooperate in these efforts. This will enable us in future to receive and pass on fresh information.Sleeve bearings with sliding rings made of polytetrafluorethylene (PTFE) can leave extremely fine sloughage behind in varnish raw material. These particles are the cause for varnish sinkholes later in the paint layer. The diameter of these sinkholes is approx. 1 mm, i.e. the black PTFE particle is approx. 0.7 mm in length and has a diameter of approx. 0.1 mm. Mostly there are much smaller PTFE particles that cause the same problems. As an example, this object has been chosen to document this problem. Two examples taken from paint shops show clearly how even small quantities of impurities can cause damage:Painting work for a refrigerator in the paint shop repeatedly resulted in sinkholes which occurred for days but then vanished mysteriously. When the paint causing sinkholes was tested in the lab everything was fine. For years this problem could not be solved. Finally, one of the employees of the refrigerator company noticed that sinkholes were occurring only when the wind was blowing from the south-easterly direction. The culprit was about 400 m away from the paint shop on the south-eastern side in the form of a workshop where also silicon spray was being used as lubricant for maintenance work for sub-assemblies. The droplets travelled 400 m from there and, obviously, contaminated the freshly painted surfaces.In another instance, the damaging effect originated in a paint company from a compressed air pipe; vaporized oil droplets were leaking into the air from a defective plug socket of a valve situated about 15 m away from a paint container. The consequences were noticed two weeks later in the paint shop when the old uncontaminated batch of paint was used up and replenished with a new batch.Carried-over contaminants have similar effect on raw materials, plant components and auxiliary materials in the chain of involved enterprises. Naturally, paint manufacturing industries and paint shops are aware of other manufacturing defects which cause such failures in paint jobs.This makes it clear that prevention of such contaminants is not so easy and also not possible without the cooperation of our suppliers. How can we prevent the varnish sinkholes at the end of the supply-chain?The following overview lists the important preventive measures for deliveries to PURPLAN GmbH or other customers who are the suppliers for the varnish industry.

• Exclusive use of lubricants for all components of installations which do not cause sinkholes in the painted products.
• In the case of new and modified plants, cleaning of all installation components with suitable detergents is absolutely necessary.
• Spreading of substances to several products must be prevented by carefully cleaning when using one installation or a component.
• For the sake of safety in the entire area of operations, only such skin care products should be issued which do not cause any damage.
• Packaging should not become a risk due to lubricants on seals or due to drawing or separating tools left on sheet metal surfaces.
• When products need to be filtered, contamination of filtering materials and accessories should be prevented.
• A new danger of contamination lurks in every refilling process. Therefore, refilling processes for raw material and semi-finished goods should be kept to a minimum.
• These suggestions are applicable to the entire chain of involvement. You may pass these to your initial suppliers as well.

PURPLAN GmbH applies an integrated concept in order to prevent contamination of its products by implementing the following rules:

• Planned exclusion of contaminating substances
• Systematic prevention in case of doubt
• Exchange of information with customers and suppliers about their experience
• Publicise suppliers' requirements
• Unequivocal adherence to relevant procedures within the company
• Creating awareness among employees through training programmes

We were finally able to operate in this area till now without any complaints.
PURPLAN GmbH has banned through a directive high-molecular polydimethylsiloxanes and potentially suspicious material from the enterprise including its assembly shops. In our enterprise all processes are constantly monitored in order to ensure that no contaminant that causes paint defects finds its way into our deliveries to varnish industries and their involved enterprises.
Through regular training programmes for all employees who influence the functioning of the system and the evaluation of relevant incidents in the enterprise and in the industry we create trust and, in reciprocation, receive close cooperation.

We wish to point out that, considering today's state-of-the-art technology of analysis, it is not a problem for the paint manufacturing industry to concretely identify contaminating substances within the small ppm range and accurately track them to the supplier whose product might have caused the contamination.
We request you to help us by identifying possible sources of contamination in your production process, by setting them aside and, thus, avoid unnecessary consequential costs also for your enterprise. In this effort, our specialists are available for consultation. We will be glad to render assistance in qualifying the Quality Management.
Our orientation does not claim to be exhaustive. However, it gives us a chance to investigate your own processes regularly for possible a source of contaminating substances on paint surfaces and eliminate them for ourselves and for other customers facing the similar challenges.