Monday, March 12, 2012

Tools of the Trade - Working with Vallejos Polyurethane Primer

Hey guys,

after reading on DakkaDakka, that some of you have had some problems with Vallejos Polyurethane Surface Primer, I wanted to share my experiences with the product.

For this, I wanted to talk about the Primer itself, how to use it and most important, how to clean your airbrush afterwards.

The Product

The line of Vallejos Surface Primers comes in many different colors. As I wanted a more neutral tone for my minis, I opted for the grey variant. This product is specifically made for applying via airbrush, although it can also be used with a brush.

The Vallejo Homepage states: "Acrylic-Polyurethane Primer. Apply directly without diluting with airbrush or brush. Leaves a mat, self-levelling coating of extraordinary strength and completely resistant to further manipulation, which does not leave imprints nor hide minute details. Ideal for surfaces like plastics, brass, resin, etc."

Especially the "extraordinary strength"part, has been questioned by many posts I've read in the last few weeks. To this I have to say, that my experience has been quite good. I used the Primer on metal, resin and plastic resin and never had a case, where I could peel the Primer right off the model, as many others have had. My guess would be, that if the primer rubs off so easily as some have experienced, either a bad batch of product, or some leftover mold release agent could be responsible.

Using the Primer

Before I prime a model, the first step is to give it a bath in warm and soapy water. This, and a thorough scrub with a soft brush makes sure, that all the mold release agent is gone. If you skip this step, there's a chance that the Primer and all subsequent paints will have a problem sticking to the model.

I mostly apply the primer by airbrush. Before using it, I give the bottle a very good shake, till the liquid is a uniform grey color. I usually prime with my compressor set to 2 bar (around 30 psi).

The the priming begins. Use only small amounts of Primer in your airbrush at any given time. Only so much, that the part you are priming at the moment can be finished. I've found, that you often overestimate the amount of Primer you'll need. Also, less is more when using this product. You'll only need a light coat of Primer. There's no need, to cover the whole model in a thick mantle, because this will only obscure the details. Just a few passes with the airbrush should be more than enough.

An important thing to remember when using the Polyurethane Primer is to always let it cure for a bit, before you start painting. I've had very good results with waiting at least two hours, sometimes more, before I began working on a primed piece. If you take your time, the Primer will set on the model for a very durable coat.

Cleaning the airbrush

The most important part. I've learned the hard way, that Vallejos Surface Primer doesn't like to play nice with all cleaning products.

I use three substances most of the time, to clean my airbrush. Vallejos Airbrush Cleaner, Honsell Art Clean Airbrush Cleaner, and distilled water. I wouldn't recommend tap water, as the minerals in there can build up in your airbrush over time and damage it in the worst case.

I had the best results in using the following steps for cleaning my brush:

First up, you should spray out any leftover Primer you still have in your airbrush.

Now it's time for the cleaner. As I said, the Polyurethane Primer can have weird reactions with some cleaning products. Sadly, this also includes my Honsell Art Clean Airbrush Cleaner. I filled my paintcup with this and all the Primer left on the sides and inside of my airbrush turned to gunk. Which was a nightmare to clean up. I had to disassemble, clean and reassemble my airbrush three times, before I got everything out. So a big no on this cleaner.

Why it has such a weird reaction, I can only speculate. The Art Clean product is very mild and doesn't contain ammonia as an active ingredient. Maybe this is the reason, but as I said before, I can only guess.

Never use this.

The Vallejo Airbrush Cleaner on the other hand works like a charm. The Primer residue just melts away when it comes in contact with this product. Just use a few drops in your cup and scrub with a brush and you should be good to go. The cleaner works so well, that you won't even have to disassemble your airbrush, because the interior will be cleaned that good. Just shoot the cleaner through the gun when you are finished cleaning the cup and you should be ok.

Best Cleaner I've used so far.

As a last step, I use distilled water and a brush to clean any leftover cleaner out of the brush. Just rinse and shoot the contents of your cup out, and you should be good to go. A trick I picked up for cleaning is this. Cover the cap of your airbrush with the palm of your hand. Then press the lever so the air starts flowing and gently pull back. The air will take the only way out it has and blow back into your cup. This can clean up any residue left in the gun, but should be done very careful, because you will make a big mess otherwise.

My selection of additives. Distilled Water included.

And that's how I do it. If you have any questions, be sure to leave it in the comments, I will try to answer them as best I can.

As always, enjoy and have fun!


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