Paint Chips

[Illaveago]

A little while ago I was asked how to get a paint finish that would be a bit more resilliant to knocks. I have like many other people I assume have painted their bikes only to have large chips fall off from the slightest of knocks.
I thought I'd ave a go and do a bit of experimenting.
I carried out 2 tests on two pieces of steel. One piece was a piece of angle iron the other was on a piece of sheet steel. The angle iron was rubbed down to key the surface slightly, cleaned with brush cleaner and sprayed with a coat of Upol Etch Primer. Once dry I sprayed a couple of coats of aerosol base coat and then a couple of coats of acrylic lacquer once that had dried.
The sheet steel was treated slightly differently in that I gave it a couple of coats
of primer which I flatted back slightly. I then applied 4 coats of aerosol cellulose paint and allowed that to dry.
Both pieces were given a further process of warming once all of the paint smell had gone.
I subjected both samples to hammer blow treatment. the sheet steel I also tried using a wood chisel to scratch test it.
I think that the paint stood up quite well considering the treatment I gave it.

 

[Globalti]

So which one do you rate best?

 

[Illaveago]

So which one do you rate best?

I think that using extra layers primer tends to make the finish softer, a bit like a soft centred sweets. If you look at the original paint finish on a lot of older bikes there is hardly any primer and some cases none at all. The original paint is also a lot thinner. I will have to try another sample using less primer or flat it back further.
The base coat and acrylic lacquer test was on a thicker piece of steel which was less likely to give or buckle but the paint has stuck well. You can see the marks left by the hammer. I am a bit wary of single pack acrylic lacquer from previous experience as it used to have a tendency to craze due to sunlight.
There are a few more experiments that I need to try but I am thinking of spraying one of my bikes using one of these methods.
I have sprayed 2 pack air dry paint before and it hasn't been as hard as the paint finish I achieved in this test.

 

[screenman]

The crazing is solvent block, where you have applied normally another coat of laquer to quickly.

2 pack air drying? most 2 packs cure in time but heat will accelerate the process. I am yet to see a single pack as hard as a twin pack, which is why they are seldom used when a hard finish is required.

 

[Drago]

Surprised you can still buy cellulose in rattle cans.

 

[screenman]

Surprised you can still buy cellulose in rattle cans.

A lot of small bookshops have not swapped over to WB, despite all the empty threats.

 

[Illaveago]

I know of some garages that have gone back to solvent based paints due to the ease of use as opposed to using water based paint.

I am not too sure of the actual make up of modern aerosol paints. They call them cellulose but they don't have the same effect on plastic as they used to in the 70s, also the smell is different.

The use of water based paint seems meaning less when you consider the fact that the primer is solvent based and so is the lacquer. The only bit that is water based is the middle bit.

 

[screenman]

I use wb primer and basecoat, then followed by twin pack. Saves on more than half the solvents, I also find it blends easier.

 

[Drago]

Modern aerosols tend to be a polyurethane acryllic base.

 

[screenman]

Modern aerosols tend to be a polyurethane acryllic base.

And can give a good finish, just not very durable. Tip, use them warm and the spray pattern will be far better. Mine stand in warm water for a while prior to use. I have often used them then twin pack over the top.

 

[Illaveago]

The crazing is solvent block, where you have applied normally another coat of laquer to quickly.

2 pack air drying? most 2 packs cure in time but heat will accelerate the process. I am yet to see a single pack as hard as a twin pack, which is why they are seldom used when a hard finish is required.

The crazing is due to UV, as with modern headlights eventually they will break down.

The hardness of the paint is surprising as I can't dig my fingernail into either finish but I could if I was to try on the bike in my avatar which was sprayed over a year ago i

And can give a good finish, just not very durable. Tip, use them warm and the spray pattern will be far better. Mine stand in warm water for a while prior to use. I have often used them then twin pack over the top.

 

[screenman]

The crazing is due to UV, as with modern headlights eventually they will break down.

The hardness of the paint is surprising as I can't dig my fingernail into either finish but I could if I was to try on the bike in my avatar which was sprayed over a year ago i

Crazing has been around a long time before plastic headlights. However we do not know for sure that it is UV that is breaking up the UV coatings applied to new headlights, in lab tests we are finding heat has a big factor.

I import and distribute a coating for headlamps and is also WB works extremely well.

Now if you want to convert a wb to touch up talk to me as I have a long lasting solution for that as well.

 

[Illaveago]

In the late 60s early 70s a lot of the commercial paint finishes on lorries were painted using the hot spray method. The paint was a synthetic enamel and the paint would be heated to near boiling point with a small amount of thinners added. The reason why hot spraying was used, was to save time and materials. By heating the paint, the paint would become thinner allowing you to spray without the need of thinners. The fact that thinners were not used meant the actual amount of paint going onto the job would be greater, less to evaporate , less coats needed.

 

[Illaveago]

A word of warning to anyone else thinking of heating paint do not heat up cellulose as it has a low flash point. The synthetic enamel was an oil based paint similar to what you would find inside your house.

 

[accountantpete]

I had a few chips on the white paint of my Ribble and used some bathroom sink enamel repair stuff that was lying around. Primer first and then top coat.

I was very impressed with the results - real good quality finish and hard wearing. I shall have to try introducing a bit of colour to do a few other chips.