Finishing defects - Varnish leaks

The term varnish leaks, spills as they are called in production, is used for those leaks of material in the form of droplets, on the edges of panels or on the sides of assembled furniture, which dry in this form. They can be removed by sanding if they appear on the intermediate layers, but become a problem when they appear on the final layer. Causes the occurrence of the defect can be use of unsuitable material, incorrect preparation of material for application, gun defects to apply or incorrect use, incorrect use of finishing machinery.

In order not to have spillage, one solution may be to use thixotropic materials

When the object to which the sealant is applied is vertical, the risk of material leakage is very high. This is the case for finishing the sides of assembled furniture, windows or turned elements. For such applications there are materials that we call thixotropic.

Thixotropy, according to DEX, is the reversible transformation of a gel into a liquid under the influence of mechanical action. Thixotropic materials have a gel-like appearance and perform well when applied vertically. By using them, the amount deposited can be larger than usual without spillage. Diluting them is not recommended as they lose this property.

Causes that can lead to spillage

In the technical data sheets and in the technologies there are indications of preparation for the application of the products and the characteristics of the product when applied. The amount of thinner to be added, the fact that this amount depends on the temperature and the viscosity of the product at application is mentioned. If the application viscosity is lower than recommended (too much thinner has been added) there is a risk of spillage.

Sometimes spillage may occur due to the nozzle of the application gun. Thinner should be sprayed through the nozzle of the gun if, after application, it remains at rest for a short period, and the nozzle should be thoroughly washed and left in the thinner until the next use. Over time, the nozzle wears out and can enlarge, allowing more product to pass through and thus leakage occurs. In this case, the nozzle should be replaced.

Spillage can also occur if the gun is too close to the object or not placed in the correct position (in the case of spray robots) or the conveyor belt is moving too slowly.

Removal of the defect

When spillages have appeared they can be removed by sanding. In order not to damage the whole surface, it is best to carefully remove the excess hardened material with a metal scraper (țicling, as it is known in the factory). After removal, sand between layers in the usual way and proceed to the next stage of the process.

If you have such problems and want to know more about causes and solutions, write to us in the comments area at the end of the article and we will reply as soon as possible.

You can also find out the causes and solutions for other defects:

Orange peel

Air bubbles. Film punctures

Craters/Fish eye

Cracks in the film