When doing a lot of work with spray paint you may find that over time the tips of the spray paint nozzles may get clogged or gummed up with old paint from your last project. This can be remedied and you can still use the paint that remains in that can with just a few simple steps and some added parts. There are a number of methods that can get around this problem, including keeping old nozzles as your paint runs out. You can then clean these and store them for future projects as needed, and prevent having to stop in the middle of a project to clean out nozzles.
Step 1 - Remove the Clogged Nozzle
On the tip of your spray paint can is the small little button you push for the paint to escape, this can get clogged from old paint drying in the valve and leave you with a half used can of paint. Remove the spray paint nozzles and you can place them in a can and let them soak for a few minutes without fear of them melting. Put about a 1/2 inch to 1 inch of thinner in the can and let them soak for a few minutes as you get ready.
Step 2 - Blow Air through the Valve
Take your spray paint nozzles one at a time, and attach a straw into the hole where the paint sprays out. You can use the same size straw as on a WD40 can, and in some hardware stores you can buy them for more detailed spray paint work. Use one of these straws that you have never used paint through and blow out through it into the valve. This part of the spray nozzle does not have a reverse pressure release on it, and will allow you to blow air straight through, pushing the old paint out as it softens from being exposed to the thinner.
Step 3 - Spray Valve Replacement
You can also simply buy new spray paint nozzles and switch them out with your old ones, or even take the nozzle from another can that has run out of paint. The nozzles will come relatively clean from using the thinner and blowing air through the lines, however people that use a lot of spray paint such as auto detailer's and wall mural artists, generally know to keep a few extra nozzles laying around while they work to avoid being interrupted.
Step 4 - Dry the Nozzles before Use
Once they have been cleaned out, be sure to let them air dry before using them to avoid the thinner from causing your paint to streak or run from shooting left over thinner into the paint mixture. You can reuse spray paint nozzles over and over again, and if you keep old ones as you use the paint up, you will soon grow a rather large collection of old nozzles. Simply let the sit and dry after the line has been cleared and the thinner will quickly evaporate leaving a clean nozzle for future use.