I can't remember where it was or who I was talking to that the word "Gesso" came up. [jes-oh] Gesso is simply the name of art quality paint on primer. It provides a good painting surface and goes on even smoother when mixed with a little water. A spray on primer will still be more even than a paint on one, but gesso is still great for touch ups and other times you don't want to spray.
Update: Reader Deadmeat points out that primer can become useless in heat extremes as well.
- A single thick is enough for things that aren't very detailed. Gesso is usually thick though, so for detailed miniatures you'll want to paint a couple layers, each thinned with water.
- I've found White Gesso can be a little streaky, affecting the quality of your base layer. To avoid this, make sure you use long even strokes with a wide brush rather than a pointed one. Another way to avoid the streaks is to thin your gesso even more and use many layers.
- Depending on the paint you'll be layering first, you may not need a perfectly white base. The important thing is to create an even, non-streaky surface that won't come off easily and paint applies nicely to.
- If your first layer is going to be Citadel foundation paint, there's a really good chance you'll be fine with a thin layer of gesso.
- If you're working with lighter colours like yellow, it becomes more important to create a nice, even, strong white undercoat.
2 layers of gesso, thinned with water, to prime pewter.
Gesso is white and will cover even black just fine.
As with the rest of my art store products, I use Liquitex. I'm sure there's other fine brands out there, this is just what's available locally. http://www.liquitex.com/Products/surfprepgesso.cfm I'd recommend either ordering online or finding a local art store and seeing what they have. This is one of those things that you're better off going to where you'll get the better product - art supplies from art stores and tools from hardware stores rather than hobby/craft stores. (a bad primer can ruin your entire model)
+ Something gesso has over primer is you won't get a too thick base coat, since you're the one painting it on.
+ You also won't end up with a rough surface like you can get from spraying primer on in dusty environments or when it's too cold.
- Takes a few thinned coats.
- Can be streaky if you're not careful.
- As there's no chemicals, you can use it on problem surfaces such as styrofoam. (since the chemicals in spray on primer eat styrofoam for breakfast, second breakfast, elevenses, luncheon, tea, dinner and supper)
- Liquitex also carries a clear gesso which would allow you to paint or tint clear surfaces (clear or coloured film / plastic from audio stores, overheard paper, etc) for things like windows and stained glass. (Although overheard paper labelled to be used with inkjet printers already have a slightly rough absorbent side.)