A few general questions

[BeaSue]

Hi, guys! It has been a long time since I've panted with acrylics (I'm a watercolor painter), and I am kind of rusty. I will be painting a 3-ft x 1-ft wood panel, i.e. cradleboard. There will be a dark background. This painting will be varnished and will be displayed outside, on my front porch, which is covered overhead, but open on 3 sides.

1.  I do know I have to gesso and sand my board. Is twice enough?

2.  Should I add a medium to my paints?

3.  Should I paint the background first or last? I'm assuming that if I used, say, indigo for the background, it would be better not to paint the entire board with indigo and then paint my lighter colors on top of the indigo, right? I want those colors to be nice and bright.

4.  Is there a particularly good varnish you'd recommend for a painting that will be outside?

Thank you so much!!! 

[nolan]

For an outside sign you want to seal the wood really well.
Sealing - Two to three coats of gesso will seal the wood itself, make sure to coat the sides very well.
Once dry you may need to wait a few days for the gesso to cure - you don't want it to be tacky.
Background - It depends how dark the background is. If it is very dark then try to mask off the foreground area before painting it. If the background is light to mid you should be able to paint the whole background no problem.
Medium - If you need to thin the paint down, just add water.
Varnish - at least two, preferably 3 coat of varnish will do. The type of varnish to use - chat to the salesman at the hardware store he will guide you. You will want one that adds uv protection if the signs will be exposed to direct sun.
Paints - If the sign will see direct sunlight, use good quality paint otherwise the sign will face very quickly
 

[BeaSue]

Nolan, thank you so very much for taking the time to answer my questions. You have given me sound advice...and confidence!   

[Annie.]

Hi Sue,
I used marine varnish (it has UV protection and is used for boats).  I went to Home Depot and explained what I need it for.  I did a test, left one sample indoor and put the other one outside in snow, brutal summer sun, and temp ranging from -35c to +30C.  After 2 years there is was no change in color and the wood (3/4 in plywood) remained healthy.

Let me see if I can send photos...

[BeaSue]

Hi Sue,
I used marine varnish (it has UV protection and is used for boats).  I went to Home Depot and explained what I need it for.  I did a test, left one sample indoor and put the other one outside in snow, brutal summer sun, and temp ranging from -35c to +30C.  After 2 years there is was no change in color and the wood (3/4 in plywood) remained healthy.

Let me see if I can send photos...

Thanks so much, Annie! Really useful information.