Do you really need to Prime models?

One of the biggest questions I always see when people start painting their models is why do they need to prime. I mean the usual argument is that it requires equipment and buying a primer which costs more money. Much like the clear coat, primer is also important in the painting process.

If you don’t prime your models, the stickiness of the paint will be severely decreased. The leads to imbalanced paint in the finish or paint not sticking to the model which can cause bubbles. Furthermore, the primer protects the model itself from the oxidation of metals.

In this article, we are going to talk briefly about what happens when you don’t prime. Also, we will talk about what happens if you don’t prime plastic and diecast models before painting.

What happens if you don’t prime?

What happens if you don’t prime is that the paint’s adhesiveness will be decreased. This leads to lots of imperfection in the finished product including lines and bubbles made by the paint. This in turn makes the quality of your models look bad and costs you a lot more work than necessary.

Priming helps paint layers’ adhesiveness to the miniature model’s surfaces.

You will not get the same results in the absence of priming your models.

For tons of individuals within the modeling industry, priming models are taken into account as a requirement and a must-do act before applying any paint layer.

They know very well the after-effects without applying the prime layer.

But one must be vigilant to employ a skinny layer rather than a thick layer for creating the model base more robust and sturdier.

If you are not using primer on your miniature models, the paint will form a shell around your painted model and it will not be in a highly cohesive fashion.

This suggests that primer acts as intermediary support between your miniature model and paint layers.

If your painted model will get dropped from a particular height, you are going to see cracks, easily visible due to the paint layer’s bad adherence level onto the model’s surface and it also can peel off in chunks instantly.

Once the primer will be used on your miniature models, it will help the highest layers of paint to strengthen stickiness, and the paint layers will set better onto your primed model.

Your sales will be at high risk if you are not priming your miniature models because the customers might return your product after a bad experience or they even do not come later.

Priming will help your model’s appearance to be better and it will also look great after the primer job.

If you consider the competition in the plastic model industry, without using prime, your model will look terrible.

Primer establishes a strong relationship between the model’s surface and the layers of paint for which the survival period increases.

Additionally, the greasy material on any model can be easily escaped for better paint grip utilizing the prime’s teething characteristic onto the model’s surfaces.

To know more about the scientific side of priming, you may check out this article I’ve made. It talks about priming in a much deeper way going on its link between the paint and the models. Here is the article: Is priming necessary before painting?

But one question we need to ask ourselves is that what will happen if we don’t prime plastic and metals? We’ll find that out in the next section.

What happens if you paint plastic without primer?

If you don’t prime your plastic models, what happens is that the paint will have a hard time sticking to the model. The thing about plastic is it is not really good with adhering to paint. That’s why it is necessary to primer plastic models since it will act as the bridge between the plastic and paint.

We can find plastics everywhere around us. A lot of items can be found to be made out of plastic such as furniture, mobile phones cases, decoration pieces, mugs, and others.

Although there are different types of plastics used in making these things. It is really hard to find yourself in an area where there is no such thing as plastic or plastic-made items in your locality.

However, it is not an easy job to customize plastic material and give it a paint job compared to other materials such as wood, metal, and others.

Mostly, the paints will not stick to the plastic materials properly and there are high chances that the paint layers will crack off or peel off in just a short while.

This happens because there is nothing to support the plastic material to grip the paint layers.

Another important concern in painting plastic materials is the expected discolorations. So confusing!!! Then, what to do if you want to properly paint plastic materials and permanently?

Generally, primers are used to give plastic materials a good holding power for paint layers.

If you want to avoid primers, what option do you have?

There is this Rust-Oleum spray paint which is widely used for plastics to stick well and it is highly recommended by industry professionals.

However, you cannot use this spray paint on every type of plastic material since different plastics behave differently to paint jobs.

It is good enough for various kinds of plastics except for Polyethylene.

One can identify Polyethylene plastic as it is usually written on plastic materials in an arrowed triangle as “PET” in the middle with capital letters.

There will be no sanding or priming required to do this type of paint job on plastic materials but you have to ensure that these plastics do not move or bend so that the paint layer(s) can be easily applied.

Even saying that, the first and only thing which is the most important in preparing your plastic model’s surface by properly cleaning it to become feasible for a spray paint job.

Also, as you already know the importance of a primer. Don’t settle with any primer you can find. Find a good primer because as we will also discuss later, it protects the insides of your model from oxidation which is the white or green portions you’re going to see in a very old model.

if you want my recommendation, the best is the Tamiya primer which I find to always work like charm. You can find it here.

What happens if you paint metal without primer?

If you paint metal without any primer, what happens is that the metal in your model will be susceptible to oxidation. Oxidation happens when metals are exposed to air causing white or green deposits. Furthermore, the primer acts as a bridge between the model and the paint which enhances paint quality.

Moisture is the biggest enemy for all types of metals whenever they come in contact with it. It is always suggested to use a primer before continuing any paint job onto any metal surfaces, though it is not considered as a pre-requisite.

There is also a corrosion characteristic of the metals and an additional metal i.e., Zinc is added to them to develop anti-corrosion elements in primary metals.

Since untreated metals are more likely to get oxidized and rusty, a primer will be required to save them from any unexpected event before applying paint layers.

In case you do not use primer, the oxidation process will start and the tentative decay and rust will be evident on the metals afterward.

Additionally, the chemical composition of paint compared to the primer makes it vulnerable to flake off easily if there will be no supporting prime layer underside.

For metal, indeed, painting alone will not serve the permanent coating purpose.

There is also a greater chance that if the paint will be applied directly onto the metal, it will unwrap very soon.

Therefore, a primer is used to prevent this from happening.

A primer is somewhat similar to paint expect it is intended to fill in the minuscule gaps available on the material’s surface and also stick to it steadfastly.

Then applying paint over primers will adhere much better due to its high-binding characteristic with the primer.

It could also be possible that any metal might not require a primer before paint job as in the case of stainless steel which already holds the anti-oxidation properties.

There are other metals that don’t oxidize i.e., Tin.

It is widely used for metal coatings as an oxidation repellant or evasive material.

However, in the case of aluminum metal, the surfaces do not grip paint well in the absence of primer.

The aluminum metal also gets oxidized if it is not sealed accurately with primer.

I’ve talked about oxidation and how you can remove these deposits in a separate article. You’re going to find them here: Can you wet a diecast model?