I have to paint some wardrobes, they are made of Contiboard, stained then varnished,I think with polyurethane. They look horrible. I am going to use water based eggshell for a finish, but will obviously need to prepare first. I have washed them down with Sugar soap (Nicotine removal!) , and sanded over to try to give a bit of a key. I don't want the final paint finish to chip. What would be best to use for a primer, Bin or Bullseye? or any other suggestions. Thanks in advance.