The process of making sugar coating and the problems that may be faced.


The sugar coating of tablets is not as standard as it used to be in the pharmaceutical industry. This is because it has been replaced by polymeric film packaging. Nevertheless, understanding the problems that can arise when applying sugar coating can help to avoid production losses when using this technology.

1. Advantages of sugar coating.

Sugarcoated pharmaceuticals have distinct advantages.

The process requires low capital costs, the equipment is not complicated, and is relatively easy to implement.

The most commonly used ingredients are sugar and water, which are affordable in terms of running costs.

It provides an attractive and glossy surface.

Sugarcoated tablets are easy to swallow, as sugar masks the taste.

2. Disadvantages of sugarcoated tablets.

Professional, trained personnel are required.

The process is labor-intensive.

Requires a long processing time.

Sugarcoated tablets are not suitable for embossing, print identification, or labeling.

They are sugarcoating increases the weight and size of the tablet.

Sugar coatings are generally water-soluble and tend to dissolve rapidly when in contact with liquid media such as gastrointestinal fluids. One purpose of a sugar coating is to protect the drug inside the tablet and act as a barrier to external contaminants. It can also hide or conceal the unpleasant taste of some medications that patients may find unacceptable. A sugar coating can isolate and cover the core color and texture of the tablet. It also has the potential to affect the release of packaged drugs in the body.

3. Packaging technology.

The packaging technique involves repeated sucrose solution in the packaging tray and drum to recap the tablet. Four process steps are usually used in the following order.

Sealing (waterproofing) - Sealing involves providing a wet barrier to cure the tablet's outer surface.

Grossing (smoothing) - This is usually done in stages. The first step is to establish the shape and size of the tablet, and the second step is to smooth the coated area while increasing the size of the tablet to the desired size.

Coloring-Provides the tablet with the appropriate color to meet the requirements of the final product.

Grinding-Gives the tablet a glossy and professional appearance by grinding.

These processes are summarized below.

3.1 Sealing (Waterproofing)

Before any sugar or syrup is added to the tablet, the core must be sealed and completely dry from any moisture or residual solvents. After the chip is dried, a sealing layer is applied to protect the chip from absorbing moisture. The sealing layer or coating hardens the surface to protect the chip in subsequent process steps. Chip cores are usually fragile and have a high tendency to crumble. Therefore, there is a high probability that the chip will initially crumble during the coating process. Standard water-resistant sealers are usually water-soluble and made from organic solutions.

The choice of sealer formulation is influenced by the sealer porosity, as materials with high porosity absorb the sealer solution and therefore do not form a uniform coating over the entire sealer. Of course, after the first layer dries, the effective sealer is used to ensure the drug core's effective sealing.

Commonly used sealers include shellac, zinc oxide, cellulose acetate phthalate, poly acetate phthalate, hydroxy cellulose, hydroxymethyl cellulose.

3.2 Sub coating.

Sugarcoating technology actually begins with a sub coating stage in which the tablet's sides are ground round or shaped to the necessary appearance. At this stage, the pills are crushed flat, and color may be added.

There are two methods of subcoating.

A gummy solution or syrup is applied to the tablet. The tablets are then dried. The process is repeated until the desired shape of the tablet is achieved.

After the dry powder is applied, the gum/saccharide solution is applied. After application, the excess water of the gum/solution is removed by drying and hardening the surface again.

The base coat is usually applied alternately with the adhesive solution and the sprinkling powder (talc or calcium carbonate) until the desired shape and consistency are achieved.

Remove excess water every time you apply syrup.

3.3 Grossing (smoothing)

The grossing or honing procedure involves filling and smoothing irregular features or areas of the tablet. After each filling step, the tablet is smoothed by grinding and trimming the pill to achieve a smooth finished appearance. During this process, the size of the tablet also gradually increases to the required extent.

Suppose there are many irregularities in the tablet. In that case, workers can use a grossed syrup, which contains suspended solid particles that better fill the tablet gaps than the sugar solution. Generally, about 60-70% sugar solids answer is sufficient to smooth the tablets. The solution usually contains a mixture of starch, pigments, acacia, gelatin, and, if necessary, opacifying agents.

In some cases, pigments may be added to the hair stage to give a uniform appearance.

3.4 Coloring.

Coloring the package is the most critical penultimate stage of the packaging process. This is because a lot of sugar solution must be added to ensure that the intended color is achieved. Historically, soluble dyes have been used to provide the necessary color because these dyes stick to the film surface during the drying process. But now pharmaceutical companies prefer to use insoluble certified aluminum lake pigments. These materials give color to tablets by dispersion. Lake pigments are produced from dyes but are oil-soluble (but generally insoluble in oil) and mixed with oils and fats. Other carriers such as propylene glycol, glycerin, and sucrose (water and sugar) can also be dispersed or suspended.

3.5 Grinding and printing.

The final step in the sugar coating technique is the grinding step. The purpose of this step is to give the tablet a shiny and unique appearance—application of waxes such as nutmeg wax and licorice wax.

Beeswax and hard paraffin wax are used to grind the tablets in an abrasive disc.

Finally, tablet markings or brands may be printed on the tablet surface with edible ink.

4. Common problems that may occur during the sugar coating process and their solutions.

①Tablet coating breakage.

This is usually caused by low or insufficient polymer concentration.

More polymer is added to the coating solution.

Another reason is the amount of pigment and insoluble fiber used.

Reduce the amount of filler.


Stress relaxation or moisture absorption during or after packaging and swelling of the tablet.

Consider using a seal coat or extending the time between icing and compaction.

③The coating does not dry.

There is too much trans sugar.

Avoid excessive heating of sucrose syrup under acidic conditions.

④Binding together.

Altered punching.

⑤Uneven coloring.

Poor distribution of coating solution.

Add enough liquid to ensure adequate mixing.

⑥Color change due to insufficient/too fast drying.

Optimize drying conditions and use pigments.

⑦Uneven base coat.

Achieve the necessary smoothness during the application of the base coat.

I was cleaning off the backside of the pigmented coating.

Avoid over-application of color solutions.

⑧Excessive drying between color applications.

Optimize drying conditions.

It was blooming and sweating.

Additional moisture in the tablet coating.

Proper drying to ensure appropriate humidity.

⑨Uneven coating surface.

The smoothness of the coating must be ensured before grinding.

Sanding sugar coating machine (grinding sugar coating machine) is the latest design and manufacture of sinofude, which is the necessary equipment for coating sanding sugar on products that need sanding sugar coating or other particles such as jelly/rubber candy or marshmallow formed without starch molding or mug wire molding. The granulated sugar coating machine adopts stainless steel SUS304/SUS316 (optional) rotating drums. Double-layer structure with holes in the inner drum, the remaining sugar is recycled until the sugar is fully coated with sugar during average production. The sugar coating machine can also control the sugar unit when selected for continuous production. A steam conveying device can also be installed to achieve a better sugar-coating effect. 


Simple operation, continuous, easy cleaning, and uniform sugar coating are the main advantages of the sinofude sugar coating machine.


Sugar coating machine effect:


Sugar coating machine effect 

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