Hi Roger H
Paul looked at the rims on my bike that had been “powder coated” some years back. Due to the use of tyre levers to change tyres, which is very frequent and expensive the way Paul rides, the “powder coating was extensively chipped.
As the coating was thick, this left sharp edges of this brittle coating.
Paul noted that he had known this cause punctures.
I looked at it and decided he had a fair point.
For racing, if I have unplated rims, I would in future get them phosphated only.
For a presentable road bike, then two pack polyeurathane done in a commercial spray shop with correct safety gear is good, otherwise there is very little better than the traditional coach paint that can be hot sprayed or brushed.
I am not really a paint specialist, but did run a spray shop as part of our old machine tool factory production.
Happy Christmas and Kindest Regards to all.
Roger

3252 Painting 03-01-06

Hi Roger H
I may be showing my age here! Many years ago, I had a home built camper built from a MB Stuttgart 408 panel van. When finished, I wanted it painted nicely and decided I needed a professional job.
I took it to a traditional coachbuilders. They told me that although there were many two pack paint products available, the best result would be to hot spray coach paint. As far as I understand, consider the following.
The problem with most painting processes is the fact that the paint applied is quite thin and has to be built up in layers.
If you use a traditional coach paint applied by brush, (the name Valspar comes to mind) then you can achieve a good depth of very durable paint.
We have all seen the very remarkable results achieved by a talented and patient man with no more than a brush and a tin of paint.
As explained to me, the same brushing paint is heated till it is then thin enough to go through a spray gun with a biggish nozzle, and so can be applied in this way. Result, thick durable traditional finish with good even cover. I give them full marks, it was a great job and far outlasted the life of the vehicle.
As I explained, I used to have a spray shop, but to paint the machine tools we used to make. I tried many systems to get a good durable finish that would not chip easily and would be resistant to damage.
I found that traditional enamel paints would not stand cutting coolants and were too soft.
Two pack epoxy was a nice finish but was too hard, so that a knock would easily chip it.
I found two pack polyurethane the best as it did not chip easily but kept a good finish.
The preparation is very important. Start smooth, clean and free from grease.
Next a light spray over with polyester spray filler key coat
A light rub with fine abrasive paper dry to remove odd blemishes
Fill in any depressions with polyester filler (Car body filler)
Smooth down evenly.
If you have rubbed through in any place, apply another light spray filler and light de knib
Now you have a good clean grease free base coat, but the secret is that it is porous like coral and the top coat will partially wick into it and achieve a mechanical key.
Be sure to blow down well to remove loose dust
Now apply top coat.
I did bike parts like this and it came out really well, but in truth, the trick is
to get your base coat on correctly first.
This process gave a very durable and presentable job. I remember Ford engineers who had come to pass off machines we made for them remarking “I wish we could get such a finish on our cars”
The finish was better then required or expected for a machine tool in a factory, but then I had another agenda!
The operator would see that he was on the best looking machine in the area and would deem that he had been selected because he was the best operator. Hence his status was linked to the machine. He wanted to maintain his status, so looked after his machine. If it made the slightest squeak, he called maintenance. He checked all lubrication levels regularly. Often the operator would even buy his own polish and clean the machine like a car.
Result. The operator maintained his status.
Visitors to the factory were often taken to see this “example” of their modern plant” by senior managers, who got to know both the machine and also the operator on first name terms, thus further confirming his status.
The reliability of an already very good machine was safeguarded by a vigilant and unpaid agent on the ground, thus its reliability record was excellent and it and it’s makers kept a constant high profile.
They have fancy names for such strategies now, but I call it common sense. Everybody wins! That can’t be bad.

Sorry,polyurethane.

Strangely enough,I went out today and bought my compresser.
It has a 50ltr tank, 8bar, Output 370 lt/min (13.1 cfm), replenishment 290 Lt/min (10.2 cfm) . I am advised that it will all do small sandblasting jobs.
One hopes this is sufficient for bike bits even though it may be too small for cars. As ever, your advice is invaluable.
Regards Roger Hulett

I did my 6 month stint in the paint shop at the fire engine coachbuilders where i work as an apprentice last year and can tell you that for 2 pack paint you must have an air fed mask,though we used to paint by brush
without it,you can thin it down so that no marks are left with the brush.
im not sure what H&S would say though.

Cellulose(excuse if incorrect spelling) is a lot safer and does not require the mask but is till worn in the booth.

Two pack tends to leave a hard brittle finish where as cellulose is softer AND has a longer timespan before polishing is nigh on impossible(the paint hardens and wont buff up.

Ill be honest in thati try to brush or coach paint most of my things if possible,i use a black gloss gargae door paint,suitiable for all metals for exterior use,looks just like the proper stuff at around £3.00 for a large tin.

Stan – There are no moons orbiting Mars….
Phobos and Deimos. Mars is orbited by two satellites, both believed to be captured asteroids. This is because of both Mars’ proximity to the Asteroid Belt and their small sizes and irregular shapes.
Sorry – just saying!