The reason for pre-cleaning substrates that are to be coated is to remove grease, oil, silicones, wax & and any other contaminant. If this practice is omitted there is a significant risk that the subsequently applied coatings will suffer from a lack of adhesion.
HMG Paints manufacture 7 pre-cleaners. These different products are designed to ensure that the user has a product suitable for pre -cleaning of all substrates. The products are named: Prep Clean 800 to Prep Clean 2806. Each of these products has its own Technical Data Sheet, which gives detailed information specific to that product. These products are described briefly below.
|Product ||Strength ||Speed ||VOC ||Other Info |
|Prep Clean 2800 ||Mild ||Fast ||715 ||Anti-static, can be used on painted surfaces |
|Prep Clean 2801 ||Mild ||Slow ||760 ||Anti-static, can be used on painted surfaces |
|Prep Clean 2802 ||Strong ||Fast ||840 ||Bare metal cleaner |
|Prep Clean 2803 ||Medium ||Slow ||790 ||Bare metal cleaner |
|Prep Clean 2804 ||Medium ||Slow ||50 ||Water based, bare metal cleaner |
|Prep Clean 2805 ||Medium ||Medium ||806 ||Cleaning of new PVC |
|Prep Clean 2806 ||Strong ||Medium ||840 ||Cleaning of old PVC |
|Prep Clean 2807 ||Medium ||Slow ||753 ||Anti-static, can be used on plastics |
|Prep Clean 2808 ||Mild ||Medium ||780 ||Anti-static, can be used on plastics |
The idea behind anti-static degreasing is to remove all contamination from the surface of the substrate by two methods: Grease etc is removed while at the same time a static charge on the surface is neutralized. If a substrate contains a static charge when being coated it is more likely to attract dust. Plastic surfaces are especially prone to static charge build up produced by friction.
Surface Preparation & Condensation
After a substrate has been degreased the solvent will evaporate. This makes the surface colder via a process called evaporative cooling, (which is why you feel cold when stepping out of a shower, as the water evaporates off your skin it cools you down, this is also how sweat works too). Because the surface is made cooler by the evaporation of the degreaser this can result in condensation on the surface. It should be noted that this condensation is not always visible and that sufficient time must be allowed for the surface to regain the temperature of the surrounding atmosphere.
If insufficient time is left, then moisture can be trapped on the surface, which will result in greatly reduced adhesion. The same problem can also occur if a vehicle is placed in a warmer environment than it has been stored in. For example, if a vehicle that is to be coated has been stored outside, it should be allowed to acclimatize before application.
Use of HMG Prep Clean products
Liberally wet a clean, lint free cloth with one the HMG Prep Clean products and clean / degrease the substrate. While the surface is still wet, apply a second clean, lint free cloth to remove the Prep Clean & contamination trapped within it.
Always use two cloths, as using only one will increase the chances of redistributing the surface contamination rather that removing it. Cloths for use with Prep Clean products should be replaces regularly and often to ensure that an efficient pre-cleaning process is maintained.