Vallejo Paint – The Impact of Thinner on Adhesion

Introduction to Vallejo Model Air paint

In this day and age, we come across an abundance of information online regarding paints used in diorama modeling and various hobbies. There are varying opinions about their usage, disputes are settled over their application, spears are broken in debates over which ones are better or worse, and so on.

Vallejo paints are not exempt from this situation. There are numerous opinions circulating regarding their quality, coverage, adhesion to various materials, how to dilute them, and so on and so forth. With this article, the author has decided to consolidate the information available online and conduct tests on Vallejo Model Air paint series so that, as the saying goes, we can see it all in one place with our own eyes and make conclusions that are acceptable to every hobbyist.

The problem of varying opinions on paint quality

The following will participate in the testing:

• Vallejo Model Air paint with the number “V-71057”
• White PVC sheet
• Vallejo Gesso primer
• Harder&Steenbeck Infinity airbrush with 0.15mm nozzle

Testing methodology and materials

The following diluents will be used:

• Vodka
• Distilled water
• Vallejo Thinner diluent
• Diluent from another company (Liquitex)

The testing was conducted using the following method:

Two primer preparations were then made consisting of:

• G1 = 2 parts primer + 5 parts Liquitex (thinner) + 5 parts water
• G2 = 2 parts primer + 5 parts Vallejo (thinner) + 5 parts water

The paint is diluted in five different diluents:

• C1 = 5 parts paint + 5 parts vodka + 5 parts Vallejo (thinner)
• C2 = 5 parts paint + 10 parts Liquitex (thinner)
• C3 = 5 parts paint + 10 parts distilled water
• C4 = 5 parts paint + 10 parts vodka
• C5 = 5 parts paint + 10 parts Vallejo (thinner)

Five variations of paint dilution

But why these specific mixing ratios? The purpose was to ensure that the paint could flow smoothly through a 0.15mm nozzle at minimal pressure during testing. In this case, the paint would literally come out of the nozzle one drop at a time, creating a very intriguing pattern. Of course, in actual painting conditions, one would not need to add so much thinner.

Drying time and its relationship to paint chemistry

After this, primer prepared with formula G1 was applied to the surface of the plate in the first (top) row of squares, followed by primer prepared with formula G2 in the fourth row of squares (skipping a row in between). Once the primer had dried, the paints were applied with each of the different formulations, labeled, and left to dry.

Let’s delve into the intricacies of drying time.

Adhesion of Vallejo paint on primed and unprimed surfaces

Now, as far as adhesion is concerned, the plate’s surface is glossy, which means that paint on an unprimed surface should adhere worse. Why did the author use two different primers?

Strength of paint adhesion to the surface

In terms of the strength of paint adhesion to the surface, the author arranged the samples in the following order:

• Composition 5
• Composition 2
• Composition 1
• Composition 4
• Composition 3

Changes in the properties of the painted surface

Now, as for the changes in the properties of the painted surface itself, below are photos of the painted samples in oblique light.

Conclusions on the quality and preservation of the surface

Assuming that the brand diluent does not alter the properties of the paint and that the Composition 5 painting is taken as the reference, the photo clearly shows a pronounced glossiness of the sample painted with Composition 2.

Impact of thinner composition on paint coverage and layer thickness

Now the author decided to trace how the composition of the thinner affected the paint coverage and layer thickness.

Recommendations for thinning Vallejo Model Air series paints

Vallejo Model Air series paints are a bright representative of acrylic water-based paints with their inherent properties.

Considerations on using the Observations on Drying Time and Adhesion

In terms of drying time, the amount of water in the solution directly affects the chemistry of the process, with water evaporating more slowly than alcohols. The experiment revealed that the sample painted with Composition 4 dried faster than all others, followed by Composition 1, then Composition 5, Composition 2, and the sample painted with Composition 3 took the longest time to dry. As far as adhesion is concerned, the test showed that Vallejo paint holds equally well on both primed and unprimed surfaces, provided it is given enough time for the water component to fully evaporate, which is approximately 24 hours.

Changes in Properties of Painted Surface

To investigate the effects of the composition of the thinner on the properties of the painted surface, the author photographed each row of samples in oblique light with a daylight lamp several centimeters away and parallel to the surface. Based on these photos, the samples painted with Composition 1, which contained the branded diluent, remained the closest to the reference sample assuming that the brand diluent does not alter the properties of the paint. The photo clearly showed a pronounced glossiness of the sample painted with Composition 2. The samples painted with Composition 4, which used vodka as a diluent, acquired a clear “matte” finish, while distilled water also added matte properties to the surface.

Conclusions from the Tests

Based on the testing, Vallejo Model Air series paints are a bright representative of acrylic water-based paints with their inherent properties. While the manufacturer claims that the Model Air series is pre-thinned for use with an airbrush, it is recommended to thin them even more for more quality spraying and control of layer transparency, especially if using tools with small diameters and low pressure to achieve thin lines. If surface quality is critical, using the proprietary thinner rather than just anything is recommended, as water changes the properties of the paint and the adhesion of the painted surface compared to other compositions.

Material Considerations

If money is not a problem, it is recommended to thin the paint with the proprietary thinner. If the question of money is critical, vodka can be used, but it does change the properties of the paint and the painted surface, although not significantly. Third-party thinners can be experimented with or the C1 composition can be used to achieve a balance between cost and quality. Ultimately, hobbyists should draw their own conclusions based on the available information and their individual preferences.