The Inventive Technician: the Development of lay:art style brushes from Renfert
Posted Feb 18, 2014 in Technical
Traditionally, dental brushes have been an adaptation of Aquarell brushes used by painters. However, painters and ceramists use their brushes differently: for instance, a painter moves the brush in the direction of the hair when applying paint but a ceramist moves the brush against the direction of the hair when picking up porcelain (see Figures 1-3).
My goal was to create a brush specifically for the ceramist that would fulfill all the requirements of optimal porcelain buildup. To do this, I researched brush preferences among my fellow dental technicians and learned the following:
All ceramists have their own technique for moisture control, tapering the tip, way of holding the brush and buildup method; even the type of mixing palette used can influence how the brush functions. If the brush doesn’t behave as it should, their buildup process falters, their rhythm is lost and time is wasted.
The brush tip must be fine and, at the same time, stable. These characteristics are achieved through very high tension force, which is what keeps the tip stiff for controlled uptake and application of the porcelain. In addition, the tip must have a long life, be easily tapered and not flare out. All these characteristics, however, are contradictory, making it challenging to manufacture a brush with all of these features.
A consistently moistened brush is essential. The two major requirements for controlling moisture within the brush tip are water storage and water flow but, again, these vary depending on the ceramist’s technique. Whether the ceramist shakes the brush lightly or strongly, tapers the tip in the mouth or by rotating it over dry or moist foam, for example, influences the moisture behavior and therefore the consistency of the porcelain.
I realized I had to develop a new manufacturing concept to accommodate individual buildup technique, moisture preferences and the conflicting features of a desirable brush tip. After three years of R&D, I created 10 different lay:art style brushes which are being marketed by Renfert.
We chose Kolinsky hair which is ideal because of its load-bearing capacity. Specifically, we use tail hairs from the winter fur of the male Kolinsky marten approximately three to five years old who live near the border of Siberia and China. Due to the cold weather conditions, their hair generally has long and fine tips with high tension force and is very durable.
The natural oil content of Kolinsky hairs prevents water absorption but too little oil reduces the tension force. I developed a proprietary procedure that precisely sets the oil content of the hair: high enough so the water uptake function is correct and the tension force is only slightly reduced.
The hairs in a classically designed brush contain a mixture of different hair thicknesses and lengths that are positioned in a pyramid shape, with one long hair at the top and increasingly shorter hairs toward the outside. However, this configuration doesn’t produce a long-lasting, stiff brush tip.
I developed another proprietary manufacturing process that allows us to select individual hairs based on quality and appearance and place them in specific locations on the brush. This process enables us to bundle numerous very fine tapered hairs in the tip so the load on the individual hairs is reduced and it better maintains its shape when applying moistened porcelain. The result is that each lay:art style brush has a consistent tip but a different shape and moisture control capabilities (see Figures 4-5).
For example, the 4, 6 and 8 size brushes come in bold and slim: the bold brush has more hairs in the upper third than the slim and offers a higher moisture release.
About the author: Cim Ozyurt is a dental technician and Product Manager at Renfert GmbH in Hilzingen, Germany.
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