4. Functional lacquers
Here are some examples of functional lacquers:
- Fluorescent
- Thermochromatic
- Luminous
- Wrinkle finish
- Hammer effect
- Magnetic
- Friction
- Electrically conductive
- Structure
- Softfeel
- Antibacterial
- Chrome replacement
An individual lacquer can usually not provide all desired properties, and certain functional properties also affect other performance in various ways, for example in terms of abrasion and chemical resistance.
It is important to find out what a certain function has for any disadvantages in relation to other parts of the current requirement’s specification. Please contact us at AMB to discuss your needs or thoughts regarding industrial lacquering.
Soft feel (soft touch)
This type of lacquer gives a velvet or soft rubber-like surface that feels very comfortable. It is often used for remote controls or where you want good friction (as long as it is not wet) and a warmer and more comfortable feel when touched.
Important to note about soft feel is the following:
- Soft feel is a very matt top coat that is applied as the outer lacquer layer.
- The pleasant feeling when touched means a relatively open surface structure that is more easily affected by small amounts of contaminants from the hands during prolonged handling. Therefore, the underlying base coat should be black or dark gray.
- Soft feel has good abrasion properties but not quite the same performance as a top coat with a smoother surface finish. (A bit of a curiosity: there are cars that have been painted with this type of paint and that have even been cleaned in automatic washing systems for several years without major deterioration in the paint.)
- There is also a variant that is biocompatible.
Antibacterial lacquer
Lacquers can also have an antibacterial effect. Various additives are added to the lacquer, and these have a documented effect on certain bacterial strains. The most common method is to add colloidal silver that emits silver ions, but there are also new approaches where fluctuations in the polarity of the surface prevent bacteria from sticking and multiplying and thus meet the requirements of ISO 22196:2011. This standard specifies a method for evaluating the antibacterial activity of antibacterial treated plastic and other non-porous surfaces on products.
AMB has access to this product and since the function is purely physical, no hazardous chemicals are released, so no approval from any responsible authority is needed. The effect lasts as long as there is a lacquer layer left, while for example the ions in colloidal silver are consumed.
The efficiency is also much higher. When you were previously satisfied with a reduction of bacterial growth by 99.9%, you can now achieve 99.9999+%, which means that there are only one or a few bacteria/fungi left on the surface after the treatment, while it could be several thousand with the old additives. The polarizing lacquer has been shown to be effective against Escherichia coli (E. coli), Staphylococcus aureus, Candida albicans and Pseudomonas aeruginosa.
However, the customer must have the laboratory test the effect herself, as these tests are customer-specific.
Chrome replacement
Chromium is an element that has beautified and increased the life of car parts and many other everyday products for a long time. It is possible to coat certain plastics with a thin layer of chromium, but there are some, especially environmental, disadvantages with the galvanic processes used for this type of surface treatment.
AMB can offer various alternatives to matt to semi-matt (not high-gloss) chrome plating that are approved after hard tests by the automotive industry.
What is haptic and tactile perception?
Sometimes the terms haptic and tactile are mentioned synonymously, but there is a difference.
One definition is that the tactile perception refers to a passive event while the haptic perception is an active action.
- Tactile: to be touched by, for example, wind or sound waves
- Haptic: to actively touch objects
In the context of surface treatment, the active, haptic perception is therefore of greater importance.
Haptic perception is the active sensory registration of an object’s size, contour, structure and temperature. The haptic perception is also not, like other senses, localized to a specific sensory organ, but receives the information from a variety of types of receptors and free nerve endings that are found in the skin and in deeper tissues.
The haptic perception threshold is about 1 µm for healthy adults who are actively exploring an object. Experimental studies have shown that a single elevation of this size can still be perceived on a very smooth surface. This means that the haptic perception is many times greater than the tactile one.
What does all this mean for the surface treatment?
The plastic substrate has its given surface, but a never-so-thin lacquer layer will change it. Because our haptic perceptiveness is so incredibly sensitive, it is an often-forgotten dimension that a surface treatment adds.
Although the lacquer layers in a typical application of a plastic object at AMB may only be 40 µm, this means that we can clearly feel the change in the surface finesse or structure that the lacquer has brought about.
One should therefore be aware that the lacquer is important for haptics. Sometimes it may be negligible and the purpose is primarily to add a color and/or the protection a lacquer provides for the underlying surface. But you can also actively use different possibilities to control the haptics of a painted object.
Design is often said to be a combination of form and function. If you are a designer you should think about the haptic dimension that you can steer towards a desired haptic effect through the lacquering of a plastic object.
Some examples of haptic effects:
Soft feel
The popular soft-feel lacquer (see above) conveys a rubber or velvet-like feeling and is very comfortable to touch.
Hammer paint
This lacquer gives a surface finish that creates a net-like structured surface when it hardens. This structure, which usually measures about 3 mm, creates a visual impression of a surface that has been treated with many hammer blows and creates many small elevations and valleys.
High-gloss lacquer
These lacquers are sometimes also called piano lacquers, but there are also matte piano lacquers. High-gloss lacquers often have a surface that feels completely smooth. So there are differences between different top coats just because of their glossiness and dullness.
Then you can work with different layer thicknesses for the lacquers, but this has its limitations through what the lacquer supplier recommends in order to maintain the required and tested properties.
Leather or suede
In addition to soft feel and other changes described above, there are also other additives that are intended to affect haptics. An example is additives that give a suede-leather-like feeling reminiscent of softfeel, while other additives may feel more coarse-grained.