Wow... I gotta say this is a good topic for new guys to read. As getting the wrong paper realy SCREWS up the outcome of the image.
Those of you that are getting your paper from Walmart, Please be weary of what you are getting. I have searched every store around and the only place I can find the correct paper is WalGREENS.
The crap that WalMART has is not glossy. What your looking for in your poster board is the paper NOT to absorb the paint. It needs to stay on the surface of the poster board.
I have bought and tried from walmart, hobby lobby, office depto, office max, pamida, dollar general and the only place that has the good stuff is WALGREENS. This is such an issue that I buy them out when I go. Last time I bought 78 22x28 sheets.
To those of you that are not sure... turn your peice over when working it and see if you can see bleeding paint... make sure you dont... if you do then your working to hard for a painting that isnt goingt to turn out.
Any one want.... I can buy and cut up the poster board, and send it out to you guys..... for a small fee..lol