When painting anything in any way (regular brush, spray nor airbrush) you have to follow certain rules to keep your art look great as long as possible.
The process depends on used material surface. Wood, paper, textile, plastic, leather, rubber, metal, etc. All of these materials need special approach to preparation. Some of the preparation methods are easy to follow and don’t require much time to get us ready and some are more difficult and take probably more time than painting itself.
First thing you should think of is
how to prepare surface that paint will stick to very good without loosing the original look of that surface?
Last time I posted an article on How to Paint a Car where I covered the process of preparation for painting and now I decided to cover more and include a preparation for airbrush. For now we’re going to look at metal surface that has base and clear coat applied already. Later on I want to add other surfaces too to make a complete guide on preparing surface for airbrushing.
Metal Surface Preparation for Airbrushing
Cars and bikes are probably the most common stuff to see on Internet in airbrush galleries and they all have similar surface which is metal.
Many people having wrong knowledge about this process are doing way more that is required and some people not knowing enough about this process are just stripping the whole coat off the car leaving bare metal surface. Here I recommend the golden middle (take off enough of clear coat but not too much as the coat is very thin anyway).
Do not take off all the coat. It’s a big mistake, you have to make surface matt
In painting there is a term Adhesion, which is an ability of paint to stick to surface. Bad adhesion will cause paint to split off after some time. Because of that we have to make on our surface micro scratches and allow paint to catch.
I’ll show three different methods and compare them. As an example I use one engine hood which I have separated to three areas with masking tape.
So, this hood has base coat on and a few layers of clear coat. To achieve maximal adhesion we have to get rid of “the gloss” and make surface matt. This can be done with abrasive sandpaper or Scotch-Brites. They are going to make micro scratches on the surface and the paint is going to hold thanks to that.
The right side of the hood is going to be processed on dry and for that I’m using abrasive sandpaper with grit P800 (for dry sanding!) and Scoth-Brite UltraFine (abrasive sponge) from 3M.
Left side of the hood will be done with abrasive sandpaper P1000 for wet sanding.
There is two types of abrasive sandpaper – for dry and for wet sanding, so be sure to get the one for wet sanding
Middle part of the hood is going to be done with Scoth-Brite Multi-Flex and matt-gel 50018 Scuff-it. Here we’ll use water too.
Abrasive Sanding Paper and Abrasive Sponge
This method is the easiest and probably the most comfortable. The positive thing of using sandpaper and sponge at the same time is that we cut the time of preparing and consumptions of materials.
We can use only UltraFine abrasive sponges but this will take much more time and we will be forced to use much more of these “not cheap” sponges.
Time to start sanding. In this step we have to do really good job which is almost chaotic but regular across the surface. First we use abrasive sandpaper P800 until we loose the glossy look. Actually the paper could be enough but scratches after this grit are too rough so we have to use finer paper or in our case UltraFine sponge. If we leave rough scratches, it will be visible after painting.
During sanding we have tendency to make circular (rounded) movements where the center is sanded more than border of the circle. Take care and take your time to make it equal.
When we reach required matt effect with P800, finish it with UltraFine sponge one time across the surface.
Be very careful, especially if you do car body as the layer of clear coat is very thin. If you sand the clear coat through to the base coat this will look like a stain after you apply your painting. To cover this up is possible only with very thick paint.
In case if you planing on painting smaller surfaces (phone, laptop, PC case) than use just UltraFine sponge.
Wet Sanding With Sandpaper P1000
In this case we have to use sandpaper for wet sanding (sometimes it has mark Wetordry). The process is very easy too as all you need to do is make the surface wet while sanding.
Here the most of beginners get into trouble as it is a bit difficult to understand if the surface is ready or not. So, to see the result of our effort we have to wipe it dry from time to time.
Scotch-Brite Multi-Flex and 50018 Scuff-it matt-gel
Here we’re going to rub special matt gel (50018) onto surface with special sheets (Multi-Flex). At the start we squeeze a bit of gel onto surface and spray it with water. Then we mull it in the way like trying to rub the gel into the surface but not with really big effort. After all, the surface should look like this.
To check if the surface is matt enough we have to wipe dry a small part.
Here is finished surface after all three methods and in my opinion they all give almost exact same finish, so the only thing to consider is cost or comfort of the particular technique.
If you clear coat it again or just polish the surface, it will get the previous glossy look and you will not see the scratches. The thing is when preparing the surface the proper way is to be able to bring original surface look back without the hassle (if you’ve changed your mind).
What about bare metal surface with no coat?
Well this is easy. If there is no coat on your piece of metal that you want to use for painting you have to give it one. Depends on your airbrush paint (acrylic, nitro, urethane nor water color, etc) just sand it with sandpaper P800 and give it some base and clear coat. Wait until it’s dry and use one of the techniques I’ve described above.
If you know about any other techniques that I did not mention here, please leave a comment or send a message trough my contact page. Otherwise don’t forget to like it, tweet it or give it a plus.