Friday, 15 November 2013

Pedantically Painting Parts

Painting takes a long time you know. I certainly don't claim to be an expert coach painter but I do admire their old ways of doing these things. About a hundred years ago I painted a few vintage motorcycle petrol tanks using some of these techniques. The results made an impression on me and when an antique bike requires painting, I use the same method. Incidentally, I need to state that I much prefer to leave the original finish intact if possible. Indeed if the bike is Victorian and has any original finish, I will leave it alone. It's a judgement call of course and you may like the wet, shiny look of modern clear coat on your antique bikes. I don't and I'll explain why. The only suitable paint for an antique bicycle is enamel. Not acrylic, cellulose, two pack, clear coat or powder coat. All of those finishes can be excellent and I own bicycles with all of them, but they are all much younger machines where the finish is appropriate. Enamel has the one major advantage over these finishes, it is possible to cut the finish back and polish it to a deep lustre without any loss of colour or fear of breaking through the clear coat. Coach painters, proper coach painters will spend more time taking the paint off than putting it on. The only trouble is that it is getting harder to get proper coach painting enamel due to valid concerns about VOCs. However saying that, Resene have just introduced a new low odour (read low VOC) formulation for their enamel and it is excellent, I'm genuinely impressed by it.

Painting is all about preparation, it's a little like plating in that the finish you get is entirely depending on the substrate finish. Clean and free from rust, dust, oil and other contaminants.

These following steps are the way that I paint, it's not necessarily the best way or the easiest to get right but it works for me. It's certainly not quick but then I've already spent over two years on this so a couple more weeks won't hurt.

first step is to fill any pits or depressions, I use a modern two part epoxy system and slap it on quite liberally, you don't need to spent too much time at this stage as most of it is coming off again anyway. Then when quite dry, use a block and sandpaper to remove the excess so that the blemish is gone. I only needed to apply a small amount of filler at the cut and welded splits on the lower fork legs and backbone. The actual amount used was tiny. You're aiming for a feather edge that when painted will not show through. You can repeat as necessary.

Next step is to mask off all the bits that you don't want to paint, in my case this was all the bits that have been plated and all the larger threads that I don't have taps for.

Next I apply a coat of primer with a spray gun, this is just flashed on to get an idea of highs and lows.

I don't spray in the workshop, I just hang bits up to dry.

When dry, it is rubbed down to key for the next coat, more filler can be added to any lows remaining. For these initial coats I use Scotch pads rather than wet and dry paper, these pads come in a wide variety of grades.

Some Scotch pads, yesterday.

Then apply another coat of primer and repeat the rubbing down. At this point I would normally apply an undercoat but this new formula of enamel doesn't require one so it's straight to the first topcoat. This can be either brushed or sprayed on, it doesn't matter since the finish from the brush or spray gun isn't the final finish. Leave this for few days in the sun to harden then cut it back with a scotch pad, you don't want to break through to the primer or undercoat at this stage.

This is black but rubbed down.

Then apply the first final topcoat candidate. I say candidate because bicycles are tricky things to paint and any undetected runs will need to be sorted out properly and another coat put on top. If you do get runs, wait until very dry for a week or more and use a block to remove the run, this may break through to the lower coats requiring another topcoat.

It's not a garage darling, it's my spray booth.

I like to let my freshly painted bits dry for a day or so in a dust free environment, then hang them in the sun for a week.

Hanging out to dry.

At this point, I then cut back the finish very carefully. I use 1200 grit wet and dry paper which has been rubbed on itself to make it even smoother, you want to remove as little paint as possible. Then using lots of water and a bar of soap rubbed on the paper, very gently and carefully go over the entire finish. This takes time. You are trying to remove as little paint as possible whilst achieving a flat surface. You have to be very careful about contamination of the paper as any grit will cause swirl marks in the finish. I also do it entirely by hand as the paint is still young and relatively soft. Then hang it up for another couple of days to cure this new outer surface.

Finally polish with a gentle, very mildly abrasive polish. T-cut is too much and you'll tear through the paint with it. Take your time and do it in good daylight. The finish will be a deep, smooth lustre. Of course this is almost impossible to photograph successfully so you'll have to take my word for it. The paint will continue to harden over the next few months so treat it carefully.

Mmmm, shiny.

Mr Middleton berated me once for having 4 molecules of paint out of place, it won't happen again I tell you.

Next week, I'll paint some pinstripes on it.

In other news, I am very pleased to announce that the deck is finally done. All that remained for me to do this week was to apply the final coat of stain. In sharp contrast to the care taken to apply the paint to the bike, I just slapped the stain on with a big fat brush. It was excellent and I now have stain all over myself and a cat that was a little too curious.

In more other news, this week I celebrated my birthday. We went out for dinner to the children's favourite restaurant, Tutto Bene. I think the kids like it because it's a loud, lively very Italian restaurant and I can't tell them off for shouting. The food and service were excellent btw.

1 comment:

  1. You only have to look at the top picture to know, for a Fact, that that deck is photoshopped.