Paint Bases

Excerpt: Base is one of the major components of paint. Base is a solid substance in a fine state that forms the body of paint. It forms the bulk of paint.

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Base is one of the major components of paint. Base is a solid substance in a fine state that forms the body of paint. It forms the bulk of paint. It conveys the character of the paint. Base makes the film of the paint, opaque, harder, and elastic and prevents formation of shrinkage cracks. I had discussed in the previous chapter the basic principles of Bases so that the readers can understand them before proceeding further. It is very essential to keep in mind that Bases are invariably white without any tinting done as it is being readied for post tinting as per customer requirements rather than making it as a ready colour/shade which will only add to the inventory. The base number included on paint will refer to the different base paints that can be used to start the process of mixing the desired colour to obtain the final shade. It is the foundation that other colours are added to. Base numbers refer to the paint used to tint, or change the colour of, the paint. Typically, the higher the base number, the darker the colour of tinting paints. A base is a paint medium specifically manufactured for mixing colours. Typically, base 1 is for pastels, 2 for slightly darker, on to base 4 which is used for intense darker colours. Aside from different formulations for each base, base 4 allows more room in the can for the addition of tinting colours than base 1. The reason one can find so little information on the bases is simple – they are not meant to be sold "as-is", as they are used to formulate a chosen colour. Further, if you mix a colour in base 1 and use the same formula in any other base, one will not get the same colour. This principle has to be always borne in mind.

The difference between bases mostly comes down to titanium dioxide fill level. TiO2 is the white pigment used to give paints their whiteness and hiding power (other fillers, such as talc, add a little whiteness as well known as extender pigments). "White base" paints (the sort one would buy off the shelf to use as white) can contain some specified percentage of their solid content in TiO2. It may be around 16+ percentage in the formulation. Medium or mid-tone bases have less TiO2 (maybe 10%) while clear or deep-tone bases have absolutely no TiO2 (meaning that the paint would dry almost clear if you used it un-tinted). As you can imagine, it would be impossible to darken a can of white paint into the deep toned colours that we often see without overflowing the can and diluting the other ingredients beyond their useful limits, and so the base system allows the retailer to add all of the colorant right there in the store. The above example refers to all types of water based paint. Some slides below will explain about Point of Sales or Post Tinting of Bases.

Advantages of Post Tinting System

  • Wide range of shades as per customer choice.
  • Fewer Inventories.
  • Instant shade preparation.
  • Shade Fidelity.
  • Slow moving shades can be offered.
  • Image building in the market.

In plant tinting difficulties

  • Pigment Dispersion
  • Manual or Automatic In-plant dosing of bulk batches
  • No stringent specifications
  • Maximum Pigment loading
  • Lower in coloring costs
  • With or without just a few guide color recipes

Point of Sales Tinting

  • Use of POS Colorants save time
  • Dosing of batches starting from liter
  • Narrow specifications
  • Guaranteed reproducibility of color
  • Higher in coloring costs
  • With recipes, software and service on the dispenser

Composition of bases

Now let us turn our attention to the composition of Bases. A Formulator has a great task to achieve at the right formulation of Bases. Having decided the type of paint, ie: Low, Medium or High end first he has to formulate the white. The formulation of white may vary from manufacturer to manufacturer as they concentrate more on the final properties and performance of the paint coating. So the Formulator has a free hand to play around in this aspect. One manufacturer with 8 – 10 % Rutile in white may call it as Medium variety Paint but another manufacturer may call it as high end. There is always a conflicting opinion in this regard, and as customer who is unaware of the composition of paint largely depends on the advertisement details, technical literature and word to mouth education by manufacturer's representative, his painter and dealer who play a very important role in convincing the customer regarding the type of paint and its performance he has to choose. Dealers tend to over play in this regard depending upon his commercial arrangement with the manufacturer. However by and large bigger companies always follow the standard and accepted norms with regard to the percentage of Rutile in white. Further the percentage of Emulsion in the formulation in combination with Rutile actually decides the class/grade of the Emulsion Paint. Now let me deal with the composition of the Bases. Once the Formulation of white is decided, which is a crucial point for formulating bases, one has to check the composition of bases. Basically to put it in a nut shell in the Bases, in descending order, Rutile will be in the decreasing order and Emulsion will be in the increasing order. Further all the additives which are normally used Viz: Defoamer, Dispersing Agent, Wetting & Surfactant, Cellulosic Thickeners, Coalescing Agent, Freeze Thaw Agent etc. are used in the bases and invariably the Formulator will use his wisdom to incorporate the optimum percentage. Now with regard to Rutile, Extenders or Extender Pigments and Emulsions, they are also included in the formulation or in the composition of the bases apart from balancing water. In other words there will not be much difference between white and Bases with regard to the raw materials used. However the Formulator has to do lot of work in formulating the Bases in order to arrive at the right combination and percentage of raw materials to get accurate post tinting result at the point of sales to arrive at the correct shade closely matching to the standard or shade card. Otherwise it will lead to too many trials to arrive at the right base, which will be time consuming.

Reference

l Ppt by Mr.Devendra Gaurav, M/S Sounjanya Colours Ltd

To be continued

Author Details

Veeramani

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