How to apply paint to glass?

Thank you to you who read this article that I wrote with the aim of providing solutions to those who are looking for them for their various projects! It is an article in which you will find complete and detailed information mainly concerning the different ways to guarantee printing and adhesion on glass, which is an extremely hard, smooth, "closed" material and consequently, difficult to hang, with a classic paint or coating.

There are products specifically designed for painting on glass. These glass paints also work on ceramics and enamels.

Solvent-free type

►Transparent acrylic colours that cling to glass 60ml

►Matt or glossy acrylic clearcoat that clings to glass in 60ml – 250 ml 1L

Solvent type

►Adhesion primer for glass and ceramic in aerosol or pot

►Two-component polyurethane gloss clearcoat for glass and ceramics

I will give you different options and techniques, to allow you to paint on glass while guaranteeing perfect adhesion and good durability over time.

By following one of these techniques, you can be sure that your paint and decoration will not peel off, on their own, or under the action of heat, humidity, or even traction, detachment, following an impact or a notch.

Painting on glass, on a bottle, a window, a stained glass window or drawing and decorating glasses or even mirrors, this is possible with a brush, an aerosol, or even an airbrush (freehand or with adhesive stencils). Yes! But on condition that you prepare the surface well, use a primer or use special paint.

There is, I will show you below, a technique to create adhesion on glass, without any primer.

The paint on the glass can be a solvent paint or a water-based paint, but these are paints that are specially capable of adhering to glass. It can also be any paint, a paint that you have at your disposal, that you are used to using, provided that you first apply a primer.

This adhesion primer is completely invisible and transparent and it then allows you to apply the paint to the glass. In this article, I will tell you about two transparent primers and also matte or glossy clearcoats for glass

How to paint glass while guaranteeing good resistance over time?

Prepare the glass

The first step and certainly the most important step when you want to paint on glass is the preparation of the surface. It is a shame to apply a paint or a special primer for glass on a surface that is not healthy.

So start by cleaning the surface of the glass well. This consists of degreasing. You can use white vinegar (acetic acid), or alcohol, or even a window cleaning product. After degreasing, make sure that the surface of the glass is dry and dust-free.

Use an adhesion promoter when painting on glass

It is simply a primer, which is a specific liquid product, specially designed to stick and adhere to the surface of the glass. We choose to use a primer to paint on glass, when we need to make a decoration and apply different colors, transparent or opaque.

There is a technique that allows you to create a strong adhesion on the glass without even using an adhesion primer. I will present it to you a little further down in this article.

These are mainly totally transparent and therefore invisible primers, which can therefore be covered with any paint.

There is a solvent-based primer, which can be applied with an airbrush or a spray gun. It is a very liquid primer, which dries very quickly. Of course, it can be used with a brush or a brush if you do not have pneumatic spray tools.

There is a transparent acrylic clearcoat, available in gloss or matt, which has the particularity of adhering perfectly to windows, glass, crystal and ceramic, even if this is not its primary function. It is perfectly unremovable, once dry and it is available in small packages from 60 ml. It is a solvent-free, odorless product and therefore very pleasant to use, with the airbrush or the brush.

This acrylic primer can be tinted in the mass, with transparent or opaque dyes. I tell you about it at the bottom of the article.

Warning: the adhesion primer allows a perfect hold on the glass, but it is still necessary to apply the paints correctly on the primer? And for that, it is necessary to make sure that the paints will adhere to the primer.

This is possible in 2 ways:

1- Cover the primer quickly with paints, before the surface drying of the primer, that is to say during the 'wet on wet' interval.

With the solvent-based primer, drying is very fast. Therefore, you have to cover quickly (before 10 minutes) while with the acrylic primer clearcoat for glass, you can cover taking your time (for 48 hours).

2 - If you want to make decorations, especially complex decorations with adhesive masks, a scalpel and stencils, in this case, it is imperative to let the primer dry completely and then sand it with an abrasive sponge or 500 grit sandpaper.

Don't worry, all these micro-scratches from sanding will disappear completely once the paints or clearcoat are applied.

When you want to paint on glass it is important to choose the right product, especially in terms of its resistance. If you want to paint on glass that will be exposed to the elements for 10 years, or that will be regularly put in a washing machine, you must choose an excellent adhesion primer but also a resistant finish.

This brings us to the resistance of clearcoats for glass.

Professional clearcoats for glass

There are many paints and clearcoats, including different qualities and different levels of resistance. Clearly, avoid at all costs products sold in supermarkets and stores in public. Choose a professional quality product.

Without a doubt, the most resistant products are polyurethane clearcoats, which are two-component clearcoats (clearcoat + hardener) and which harden by polymerization. This creates extremely hard finishes and resistant to all kinds of products, solvents, acids and temperatures (around 250 °).

We offer a clearcoat used by manufacturers to coat glass or ceramics. This can be any type of object, for example wine bottles.

Find the polyurethane clearcoat for glass and ceramics. It is a completely translucent and very shiny clearcoat, which forms a layer of approximately 25 microns when dry. It is recommended to apply 2 coats. This 2C clearcoat allows total and perfect adhesion on all types of glass. It is a flammable clearcoat reserved for professional use.

We also offer the solvent-free HIKARI RC clearcoat, it is a single-component "water-based" acrylic clearcoat, available in matte or glossy, which dries in ambient air very quickly.

Having already used it personally, I was extraordinarily surprised by the level of adhesion produced by this clearcoat, but also by its resistance. It is a clearcoat that is easily usable by the general public, because it is odorless and non-harmful. It can easily withstand years and withstand machine washing with detergents and high temperatures.

Food varnish for glass

A food varnish is a tested, approved and certified product, according to a certain standard, which guarantees the absence of migration of molecules or dangerous substances from the dry varnish to the food.

There are mainly 2 types of food varnish, either for indirect contact, such as a kitchen worktop, or for direct contact. For example, this is a varnish that covers the inside of a food container, such as those in cans.

We offer these two types of food varnish.

These varnishes do not have any particular properties that allow them to adhere to different supports, including a difficult material such as glass. However, they can be used just above an adhesion primer for glass or ceramic indicated in this article.

Tint varnishes for glass

It is possible to color and tint these special clearcoats for glass, by adding concentrated dyes and we then obtain tinted varnishes or even paints.

For example, you all know the stained glass windows of churches, which color the light, thanks to a process of coloring the glass in the mass. It is possible to do the same thing with the dyes in the varnish for glass.

There are translucent and transparent dyes, or opaque dyes (which do not let light pass through).

To color acrylic varnish without solvent:

► Transparent concentrated dyes available in a dozen colors. Dosage at 5-6%.

►Opaque dyes (we offer them on request).

To color solvent-based polyurethane varnishes:

► Here are the transparent concentrated solvent-based dyes

► Solvent-based opaque dyes Dosage at 5-6%

There are many other original tips for personalizing your transparent varnishes, by giving them shine thanks to transparent pearls, or even by giving them a photoluminescent effect, thanks for example to phosphorescent powders. Dosage at 10-20%.

Promote adhesion to glass without primer

Here is a technique that allows you to adhere any paint or varnish to a glass surface, without using an adhesion primer.

Although this technique shows excellent efficiency, I recommend that you use a primer or paint specific to glass in all cases.

This method uses a phenomenon known as molecular adhesion or "covalence". It is implemented with a torch powered by gas. This is a process that is widely used industrially, with plasma torches.

However, the same efficiency can be achieved with a stove or a gas torch.

Simply pass over the surface of the glass, 2 or 3 times with the blue flame, then apply the paint, waiting a minute for the surface to cool. The flame produces a covalence phenomenon at the level of the surface atoms which will be able to attach to those of the paint.

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