I WAS IN THE PAINTERS UNION FOR 20 YEARS. I PAID IN $16,000. I haven't been in the union for 20 years. I quit because the business was slow,no work.Can I still withdraw my pension or do I have to wait till I'm 65, if so How do I do this?

It really depends on which union you joined, was it AFL-CIO or what. Many funds will allow you to withdraw everything you put in with a one lump payment. They also can allow you to collect benefits when you reach their specified retirement age but at a much reduced rate since you did not work the 20 years that they apparently require. Best bet is to call your penion fund manager which can be googled.