What are coating defects?

What are coating defects?

Colour variation arises through poor mixing, uneven spray pattern, insufficient coating or migration of soluble dyes during drying. Orange peel/Roughness is related to inadequate spreading of the coating solution before drying. A decrease in viscosity of coating solution can reduce this defect.

What are defects in tablet coating?

Defects in film-coated tablets

• Tablet Picking.
• Orange Peel/ Roughness.
• Tablet Edge Chipping/ Erosion.
• Bridging of Logos (Intagliations)
• Cracking of film coatings.
• Film Peeling and Flaking.
• Infilling of Logos.
• Tablet Surface Erosion.

Which of the following is a type of coating failure related to aging?

Cracking. Generally, a stress-related failure due to movement, aging, absorption and desorption of moisture and a lack of flexibility within the paint or coating film.

What is paint defect definition?

Paintwork is defective if application defects or blemishes such as paint runs, paint sags, wrinkling, dust, bare or starved painted areas, colour variations, surface cracks, irregular and coarse brush marks, sanding marks, blistering, uniformity of gloss level and other irregularities in the surface that are visible …

What is the first step of sugar coating?

Subcoating
Subcoating This step is regarded as the first major step in sugar-coating process. It involves the application of large quantities of sugar-coatings to the tablet core, significantly increasing the tablet weight by 50 – 100 %. Subcoating provides the rapid buildup necessary to round up the tablet edge.

Why do coatings fail?

Improper Formulation If not formulated properly, coatings are apt to fail even when proper surface preparation, application environment, and application techniques are present. Common characteristics of formulation failures include alligatoring, chalking, checking, cracking, erosion, and mud-cracking.

What is inorganic coating?

Inorganic protective layers – also called conversion layers – are non-metallic, very thin coatings on a metal surface and serve to protect against corrosive attacks. Inorganic protective coatings are usually produced by the targeted chemical reaction of an aqueous electrolyte solution with the metallic substrate.

What are the types of paint defects?

Paint Defects

• Brush Marks.
• Chalking.
• Sagging.
• Drying not proper.
• Efflorescence.
• Peeling.
• Flaking.
• Low Coverage.

What are the causes of paint defects?

Dirt, contamination

• Surface not carefully cleaned.
• Dirty spray booth and/or booth filters.
• Pressure in the spray booth too low.
• Unsuitable work clothes.
• Inadequate paint filtration.

Why is compression coating used?

Compression-coated formulations can be used to protect hygroscopic, light-sensitive, oxygen- or acid-labile drugs, or to separate incompatible drugs from each other. They can also be used to achieve controlled release, and a number of studies (2) have evaluated compression-coated time-controlled drug delivery systems.

Why is tablet coating done?

Tablet coating is the key step involved in the manufacturing of tablets having controlled release, delayed release profiles. The tablet coating have number of advantages like masking odor, taste, color of the drug, providing physical and chemical protection to drug, Protecting drug from the gastric environment.

What are the common causes of coating defects?

Causes of Coating Defects  Poor surface preparation • Surface contamination • Surface profile  Poor application • Mixing (1-pack & 2-pack) • Use of brush & roller (low dft per coat) • Use of spraying (low or high dft per coat) For internal use only – not to be circulated outside AkzoNobel Protective Coatings 5.

What does ‘surface discoloration’ mean?

Surface Discoloration ‘Coating surface has a different appearance from that when it was originally applied.’ For internal use only – not to be circulated outside AkzoNobel Protective Coatings 21.

What are the types of specific defects in paint?

Specific Defects – Film Defects 7) Peeling, Flaking & Delaminating (Detaching) • Reporting “there is serious detachment” does not give much information – or help to provide a solution. • Peeling – when paint curls off a substrate. • Flaking – when paint detaches in flakes. • Delaminating – intercoat adhesion failure.

What are the specific defects in surface preparation?

Specific Defects – Surface Preparation 1) Blast Profile Effects • Profile too small gives poor key for adhesion • Profile too large means peaks may protrude through the paint film as paint flows away from peaks. Steel Profile Paint barely covering high peaks of blast profile.