Varnish and paint additives that make your work easier

Additives for varnishes and paints are products that are primarily aimed at those who finish in factories, i.e. professionals. With their help, the final appearance of the film can be improved or unpleasant application surprises can be avoided. Some additives are also available in DIY stores. They are the easiest to use and make coarser "adjustments". In the case of those used in industry, we are talking about fine tuning for the best results. It's a good idea for applicators to have a collection of these varnish additives to help them solve problems quickly.

Additives are substances that are added to the varnish in very small quantities, from 0.1% to 3%, rarely 5%. But the effects are remarkable and the quality of the final film much improved. They can be divided into several categories: additives that change or improve the appearance of the film, make application easier, remove certain defects or prolong the life of the liquid material (before application). If you are involved in this area of your factory's business, it is a good idea to talk to your varnish and paint supplier about purchasing additives. You don't need large quantities, a litre of each is sufficient.

I do not propose to describe each additive. It would also be difficult because each manufacturer has its own additives that can sometimes solve several problems. To give you an idea I will tell you about them by grouping them into a few categories.

Additives that improve the appearance and properties of the varnish or paint film

Degree of gloss of the varnish is the one with which we can assess how glossy or matt the film will be. Sometimes we want the lake to be less glossy. We're not talking about radical changes but a 10-15 degree decrease (maybe a little more). In this case we use flattering agents.

In order to be easily mixed into the varnish they are in liquid form, being dissolved in resins. In this case it must be specified whether water-based or solvent-based lacquer agent is desired. Liquid agents cannot lower the gloss below 20 (rarely 15) gloss. For an even lower gloss, powdered wetting agents are used, which can be used for both water-based and solvent-based lacquers. Mixing must be done very well (with special machines) to obtain a 'clean' film with uniform gloss.

There are additives that make slicker film and more pleasant cough. This will make the furniture more pleasant to the touch and easier to maintain (the dust cloth does not 'trip').

In order to make products used outdoors more resistant to solar radiation, a UV absorber. The film will be stronger and the wood more protected if the finish is transparent. Be careful though, if the wood used is not resistant to the outside the added absorbent will not prevent discoloration over time.

Additives used in the application of finishing materials

Most additives are used for the application of varnishes, lacquers and paints. There are different stages of application, different ways of application, different types of wood to apply to and for each there is an additive that can help. For example casting application or flow-coating of water-based products, the varnish or varnish may foam a lot and the application may not be uniform. In this case it is necessary to add a defoamer.

In order for the varnish or paint to sit well on the surface of the wood, add additives that "wet" the substrate better, making the lake loosen upto stretch better. There are products that reduce surface tension and you can find them under the name of releasing agents.

To avoid leakage when applying vertically or on parts with carvings or millings, use thixotropic lakes. There is also thixotropic agents which can be added to varnishes and so will not tend to leak easily.

When the wood to be applied is tannic, acidic or basic in pH, properties that can change colour or influence drying, the addition of specific additives can solve the problems. There are anti-tin additives or pH-regulating additives.

Additives that reduce or extend drying time

Drying of finishing products is not always related to solvent evaporation. In the case of UV-curing varnishes or two-component varnishes, the chemical reaction that leads to the hardening of the varnish can be slowed down or accelerated with additives. It's all about what you need. Faster curing shortens working time and slower curing gives the varnish time to set very well (very useful for gloss varnishes).

Atmospheric humidity can sometimes influence drying. In this case too, things can be improved by using a specific additive.

Additives that help reduce defects

In the pages of the magazine you will find a series called Finishing defects which describes at length the defects that can occur during product application and how you can avoid this. When defects are likely to occur (cracks in the film, poor adhesion to the substrate, bubbles or opalescence in the film) it is good to use the right additives to reduce this risk.

There is anti-crater additives, very good if there is silicone vapour in the area (from fitting windows) or additives that increase adhesion when applied to chipboard or glass. A very small amount of additive added will save you a big headache.

Materials or methods with the same result as varnish additives

There are plenty of other varnish additives that can help, I certainly haven't mentioned them all. For example, if you work with water-based products, you have anti-fermentation additives which prevents the product that has been diluted with tap water from altering on very hot summer days. When staining wood with berries you can use additives for standardisation, additives to better mark the pores or for some effect (positive staining of resinoids). And the examples go on.

These are operations that can also be adjusted using other materials. Diluents are of great help when drying solvent-based finishing products because mixtures can be made to meet precise requirements. Fast evaporating thinners can be used for fast drying and heavy volatile thinners for delayed drying. With water-based products it is more difficult because there is only one solvent - water. In this case additives are very useful.

Application methods are also important. To avoid the appearance of a defect, another way of applying the product can be chosen without adding additive.

Varnishing, staining a piece of furniture or other wooden product is important and should be done to get the best results. Because the finish is what sells. I have said many times that you can have the best quality wood, if the finish is ugly, the furniture will remain unsold. And a poor quality wood can be improved with finishing. So, if you can use additives to achieve perfect surfaces, don't hesitate to do so.

I hope you find the article useful. If you think others will appreciate it, you can share it. And if you have any comments, questions or additions, please leave them in the space provided. It will be a good opportunity to discuss finishing 🙂