My earlier painting techniques involved various combination of brush, rattle can and air brush - both with and without primers. I am building a new layout and I would like to improve my painting skills at the same time. I am confortable with an airbrush and will lean in that direction most of the time. My biggest question is how different primers (clear, gray, black, white, etc) impact the color or texture of the top coat. I tend to use a gray primer most of the time but I can see where other primer colors might be better for different color top coats.
I have been thinking about making a set of color boards which would have a bunch of the various primer choices applied in strips as a base coat and then add the top coat over the whole set of primer coats to see how the primer impact the appearance of the top coat. To do this, I would make up a bunch of test pieces with the various primers on it and then as I get ready to use a new color topcoat, I would apply the topcoat to one of my primer test strips to see what it looks like when dry. As each test strip is finished, it would be added to my collection of paint test strips for future reference.
Before I launch into this project, I would like the opinions of those who have a lot more experience with painting than I do. Is this a waste of time? Will I discover that the primer type or color has minimal effect on the finished topcoat? I would be very happy to skip this step if forum members can give me enough insight into the answers to meet my needs.
PS: I typically use Vallejo acrylic Model Air or Model Color paints.
This sounds like a good idea and one that should give you some clear choices in primer colors based on the final topcoat color. I know from past experiences in automotive painting that the primer color does affect the appearance of the finished topcoat although not significantly. Generally a light grey or white primer is used for light colors or in some cases ‘bright’ colors like reds or yellows. The darker primers are suited to dark topcoats. The major advantage is that it will take fewer coats of the topcoat color to achieve the desired finish.
I generally use the light grey primer on most of my models because it will work with most colors including the blacks and dark greys; however, I still prefer to use the dark grey automotive primer for dark topcoat colors as any lightly coated areas (where fine details are present on the model) will still show up as the desired color. I don’t know if this makes any sense to you but this is how I like to work with paints/primers/colors on model surfaces.
Since you are working primarily with airbrush finishing, these primer/topcoat combinations should be more obvious to you as you develop a collection of them. Again, I think your approach is a very good one. Let us know how this works out for you.
One other function of a primer is to give a uniform color to the model to start out with. If you add detail parts, they come in differnt colors from metalic colors from cast metal parts to greys and tans for plastic or resin parts. If not primed, these various colors will influence the color of the final coats.
My view on primers - which includes a lot of the previous replies - is:
primers give a solid base for the finish coat(s). By that I mean it covers up color variations on the subject, and provides a good “foothold” for the finish paint.
I would match the primer to the finish coat. The primers I’ve used are white, grey, black, and a boxcar like red. So if the finish paint is very light, I would us white. If very dark, I would use black…and so on.
Using a primer can have a downside. It is generally a bit thicker, and can cover/smooth out small details in the painted object. That said, sometimes its best to not use a primer.
If I were going to do a color panel like you want, I would start out by making 1 verticle line of each primer I had, side by side. Then I would make 1 horizontal line of each color I wanted to use one over the next. Then you would wind up with a screen looking panel with all the visual combinations of primer and color.
That is a very good point. If you are going to use automotive primers, some of them are designed to fill in imperfections in the surface. Obviously you want to steer clear of those if you are modelling.
Great info. As the OP, you bring up several points I had not considered such as the need for multiple coats to get the topcoat to look right. I am primarily focused on structures rather than rolling stock so a thicker primer is not as big a concern for me in hiding details. I think I will go ahead and make up some primer strips like I mentioned and then as I start to use a new color where I am concerned with the final topcoat color, I will paint on a primer strip first and see what works best for that specific paint color. As an example, one color I am concerned about is the yellow on a ATSF wood depot. I think the original ATSF color was called “Colonial Yellow” which was a light creamy yellow. I have seen suggestions for the best way to get the color right but they all involve Polly Scale or other paint combinations I do not want to use. I have seen suggestions that the Vallejo Model Color 70.858 (Ice Yellow) is supposed to be a decent match to the Colonial Yellow. I think this will be my first test strip to see how it looks.
Any of the lighter colors (orange, yellow, white, red) should start with a light gray primer. I use Tamiya primer, it is very thin, and goes on smoothly for a rattle can paint.
It’s really a matter of how many coats of the finish paint you need to cover the primer. With enough topcoats you can cover anything. But if you choose a light primer to go under light colors, a dark primer under dark colors, and red primer under red, your finish coats will cover the primer with only one or two coats. For model painting you want a thin paint job, thin as possible to avoid hiding details. Model painting is not like automobile painting, where you can just keep spraying on coats and rubbing them out.
Most of the time, most of us, want the finish paint color to be the top coat color. In actual fact, the primer color will show thru and give a tint, or something, to a thin topcoat. Sometimes this works out, but more often we want the topcoat color, just like it shows on the bottle of topcoat paint. Which is why gray primers are effective, gray is colorless and doesn’t effect the color of the finished paint job.
I use Krylon or Rustoleum auto primers in rattle cans. They stick to anything (especially metal), they cover anything, and they offer a fine dead flat surface for the top coats to stick to. For that matter, the dark gray auto primer is a fine color for steam locomotives, and the red makes a good boxcar red or brick red.