Water-based paints - 55: Manufacturing guidelines of bases

Excerpt: Now let us turn our attention to the manufacture of Bases and the precautions one has to take during the process

Now let us turn our attention to the manufacture of Bases and the precautions one has to take during the process. It is very essential that Bases so manufactured should have almost the same property in all the batches or else the tinted bases will show shade variation from batch to batch. This is not at all desirable as it will create a chaos in the market. Such variations will not be accepted by the dealers and Painters/applicators as shade variation in one wall will spoil the aesthetic appeal and will lead to customer rejection. The manufacturer may lose his creditability and good will. In order to avoid this there are quite few precautions which are to be observed so that bases manufactured are without any variation, post tinting. The following broad precautions can be listed:

  1. Do not change the production parameters like the sequence of addition, RPM of the high speed disperser at various stages of manufacture and already set structured formulations which were validated in the R & D Laboratory. These are very sensitive parameters if, when changed or altered, can lead to different characteristics of the bases made.

  2. Procure the raw materials or extenders from the same source as variations in the extenders may affect pastel bases, post tinting. It is very important to maintain one approved source. In case a particular extender has to be procured from a different source, due to non availability, a sample of such extenders should be first tested in the Lab for the basic parameters of the extenders. Then a 1 kg batch of the Base should be made and green reduction should be carried out following the drawdown. When compared with the standard, if no variations are observed it can be substituted in the formulation and production can be carried out. But if any variations are observed the base should be subjected to further test like dE if spectrophotometer is available, or samples of base should be tinted in the lab with varying percentage and compared with the standard. If still any variations are observed one need to visit the formulations for a possible change to suit and match with the standard. Fresh trials are to carried out by varying the percentage of the extender in question till such a time the base is matched with the standard. After all these exercises, the results are recorded and the final green reduction card with the standard should be preserved in the Lab for future reference.

  3. Good plant practices should be adopted, like first in first out in respect of all the raw materials should be followed. This is very essential to ensure the raw materials especially the extenders which were used for standardising the bases are consumed first so that when a fresh lot arrives it does not get mixed up with the earlier lot. Otherwise it will be very difficult to pinpoint which extender from which batch/supply is responsible for the variation in the bases, resulting in utter confusion. As a result the complaint investigation becomes frustrating and one cannot come to a firm conclusion. Therefore the FIRST IN FIRST OUT (FIFO) should be practiced well in the plant by all the employees concerned. This practice should be extended to all raw materials particularly in case of the extenders. Also if any raw material which has short shelf life should be consumed /used in production first. I had explained and emphasised this point under the heading Production of Water Based Paints earlier.

Manufacture of bases

Manufacture of bases is similar to the manufacturing process of white. In case of BASE I, II, II and D-Base, it is not in any way different than the white. The already standardised Base formulation is followed and the batch size is determined. Once the base is manufactured it is very important that it is subjected to green reduction test, draw down cards are made and compared to observe whether any variation is observed. If the plant has a spectrophotometer, the base is subjected to scanning with the standard and the dE is checked. This is to ensure that the dE is as close as possible to the standard, as this will ensure good matching of shades after tinting. It is also essential to check the Brightness Index, Yellow Index, as described in the previous chapter, and recorded. These records will serve as future reference when similar batches are made in future. Manufacturers are advised that every batch of Base manufactured should undergo this Quality Control check, in order to have uniformity in the bases, so that there is no batch to batch variation reported from the POS tinting. The manual standardising procedures are elaborated in the Chapter.53; this may please be referred to by the readers.

Drawdown cards for bases – an important tool

Everyone must know that the truth is that every successful paint factory and paint manufacturer must rigorously and continuously test the paint they produce to guarantee that each batch is up to the exacting standards required in the commercial paint sector. In order for the professional painter/applicator/contractor/end user, to have confidence in the paints manufactured, one must first have confidence in the brand of paint they are using. While the customer or client might not ever notice a subtle difference in things like colour or gloss, a paint manufacturer's reputation is staked on their customers – painters and paint professionals – trusting the products they produce each and every time.

The simplest way for these manufacturers to test the colour, opacity, and gloss of a paint sample begins with a drawdown card. As the name implies, a drawdown card is a piece of firm card stock that features a black portion and a white portion. Drawdown cards can help measure colour, spread rate, opacity, bleed, viscosity, thickness, gloss, and a wide number of other physical properties critical to identifying the specific qualities of a particular paint. Regularly confirming that these properties are within the designed specifications of the paint being manufactured and is the first step to guaranteeing that the end-user never faces a recall or unforeseen paint issue. Drawdown cards are most often used when paint is being manufactured or when a designer is comparing paint colours. As a result, you may not be familiar with draw down cards and their myriad uses. Painters may rely on paint swatches to confirm colours, but drawdown cards are significantly more accurate, as they offer a larger paint sample area and multiple colour contrast pallets. Applying a sample of paint to a drawdown card and spreading it over the card at a consistent speed creates a thin film covering that can be analyzed for colour, gloss, and reflectivity. Drawdown cards work by measuring the contrasting properties of the paint on the white portion of the card and the black portion of the card with the same sample of paint. These differences allow for measurements that determine the exact colour properties of paint before it is used for a commercial painting contract work. It might seem that actually using a drawdown card would be a difficult or messy process, but nothing is further from the truth. Drawdown cards are relatively inexpensive items, as applying a sample of paint as a thin film is simple and quick. Plus, it can save you lots of time and trouble down the road by catching problems with your paint before the start a painting work. When we think about testing paint, we most often think of either complicated chemical tests or a quick “eye test”. In reality, there are a number of tests that take place in factories and test facilities every day. Drawdown cards are simple to create and offer much more informative, meaning that if you are Not using drawdown cards regularly, and you are missing out on a wealth of information that can help you do a great job.

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