Paint Defects 7 – Orange Peel
- 22 July 2016
- Posted by: Stm Coatech
- Category: Educational Articles
Orange peel refers to texture in the finished painted surface similar to that of an orange skin. Excessive orange peel is commonly caused by a paint process in which the paint does not sufficiently ‘flow out’ on the part in either the application, flash, or curing phases.
This is a easy term to remember, because it is actually referring to the peel of an orange. The peel of an orange has a bumpy texture. Now if you look close at all paint jobs, even new from the factory, there is orange peel present. The only time there is not, is if the surface has been cut and polished (buffed) like a show car. However, it is the excessive orange peel that become the problem and becomes an undesirable finish to the customer.
When we were discussing spraying techniques and how the spray gun atomizes paint, we said the paint is broken into tiny drops so that it could be transferred from the cup to the car. When the drops are too big or too dry when they hit the panel being finished, the drop will not flow together and level out as they should. In order to reduce the orange peel to an acceptable amount is to find a way to make the paint drops smaller or a way to spray the paint wetter.
Orange peel is often caused because of poor gun adjustment as the paint is being applied, although it also can be caused by incorrectly reducing the coating before application. Gun setup and adjustment are critical to a smooth and flat appearance of a coating. If the needle/nozzle combination is not specifically matched to the coating being applied, the air pressure – especially when using an HVLP (high volume low pressure) gun – is not sufficient to atomize the paint properly. –
• Schedule painting to avoid temperature and humidity extremes.
• Select the thinner or reducer that is suitable for existing conditions. The use of a slower evaporating thinner or reducer will overcome this.
• Allow sufficient flash and dry time. Do not dry by fanning.
2.Axalta Coating Systems, Paint Defects Manuel, data of access: 21 July 2016, http://www.axaltacs.com/content/dam/NA/HQ/Public/Axalta/Documents/Brochures/Axalta-Paint-Defects-Manual.pdf
3.Lusid Technologies, Painting Defects, data of access: 21 July 2016, http://www.lusidtechnologies.com/index.php/paint-defects