Tuesday, August 22, 2006
SANDING AND PRIMING THE FRAME AND FORK, AT LAST!
Ok, I decided to follow my own advice for once. I was about to start my first bicycle repaint job in many years and on top of it, I was going to try a new primer. So i decided to start with the fork, which I usually keep for last. My goal was to prime the fork, post about it and do the frame later.
WELL, I liked the end result so much that I primed the entire thing! That fork looked like a piece of candy after I had finished priming it. That white krylon primer works great. So naturally I was curious of how the frame would look, so I went ahead and primed it as well.
I started by cleaning the fork with paint thinner and then did a once over with 320 grit sandpaper to dull the paint. I then went after the dings and scratches to eliminate them all. After I was satisfied, I applied the primer.
Always start with the interior of the legs and the little nooks and crannies first. The exterior of the legs are the ones that are easier to paint because they are the obvious thing you see first and they are easier to reach. You don't want to start shooting primer to fill those little spots you missed after a perfect shot of primer on the most visible area. This is a perfect way to ruin it with overspray. I usually do small sanding touch ups after priming and then apply a second coat. But in this case I was satisfied with the end result. I put the fork in the sun and headed for the frame.
Before I started, I had to remove the fender brace on the seat stays. I'm going to put in 20 inch wheels and fenders on a 24 inch wheel frame. There would be one ugly looking gap in between. I know that this will affect the rigidity of the frame, but I don't really care. I started by cutting most of the brace off. I though that I could break the welds off, I though wrong! So I went to the grinder for the biggest chunk, went to the Dremel tool for the medium part, went to the metal file for the small part and finished it off with putty and sandpaper. I did sweat a bit, because I was afraid I was going to go through the frame, but I didn't. The result looks great. I then used thinner and my nails to remove the last of the sticker glue on the seat tube(lighter fluid didn't work). I could now finally clean the entire frame with thinner and start sanding.
I had so much fun with the metal file, that I used it first to take out dings, scratches and some original defects out. I then finished the frame with 320 grit sandpaper by hand. I then used an old fork in my retired work stand(which is for sale for anyone in Montreal interested) and just dumped the headtube of the frame in it upside down. Yes, upside down. Always start with the bottom of the frame and all those little nooks and crannies. Same principle as in painting the fork.
Start with light passes until you build up a decent coverage. Keep a small rag to clean up the nozzle of your paint can every 2 passes. Paint builds up on the nozzle and you end up with paint spatters all over your paint job. Once you are satisfied with your handy work, turn the frame over and do the top. Once you are all done, wait not more then 20 minutes and do a second coat. Leave the frame in the sun for the primer to bake.
Paint takes time to dry. Even when it is dry to the touch, it's still not dry underneath the surface. You should wait 24 hours until you apply the color coat. Go over your frame and do little sanding touch ups if needed and apply another coat. This has to be done within 20 minutes. The primer won't be really dry and will still react to the thinner in the primer and will blend perfectly.
I don't have a garage, so I work outside. If you're stuck like me, you know that you need a nice warm sunny day. Keep in mind that dust, bugs and all kinds of foreign matter can end up on your perfect spray job while it is wet. Take note of the wind direction and vulnerable objects close by like the family car or your spouses favorite gnome! Paint travels with wind and were it lands...it stays.
Whatever you use to paint your bicycle, may it be a brush, spray can or a professional spray gun set-up, remember that the quality of your paintjob is totally dependant on your preparation work. Cleaning and sanding before you shoot one drop of paint or primer is as important as the paint job itself. Take your time.
Until then, keep your hands dirty.