An Hypothesis About Camera Painting

[ruben]

Now that I am reassembling my shooter Kiev, something of interest perhaps has happened, concerning camera painting.

My shooter has a front black plate purchased from Alex, while the top and bottom plates I painted myself. The winding knob was replaced at the time by one belonging to an Olympus RC.

To shorten the story I will just say that I want to paint again the top plate and the RC rewinding knob. And I mean taking out the previous black painting and premier layer (*).

The top plate was originally painted and backed at my kitchen oven at a temperature of approx 40 centigrades for some six or eight hours. But the rewinding knob, due to a mistake of attention, after getting the premier, was put in the oven for one hour before the black paint, but at 250 centigrades.

So when I took it out at the time, the premier looked as an overcooked cake, with some small stiff bubbles and an overall heavy creamy colour. In spite of it I preceeded to black paint it as I was short of time.

Now that I immersed both the top plate and the RC knob into thinner, both the premier and the black of the top plate went out easily. But the premier of the RC knob remains as stiff as rock.

This leads me to the speculation that if instead of overnight backing at low oven temperature, I leave the parts for 24 or 48 hours, this may strengthen both layers of paint.

Or in other words, that the "secret" of permanent painting is very much in the way of the drying. Time and temperature.

Cheers,
Ruben

(*) The "premier", is a type of paint sold everywhere paint is sold, that interfaces between the outer paint (black for example) and the sleek chromium of the camera.
When you go to purchase a paint for your camera you will look obviously for paint designed for metals. But all paints designed for metals don't really get fixed to the sleek chromium of a camera, and hence the need for the premier to interface

 

[TVphotog]

What may have happened is thus: the higher heat, caused the metal to expand and opened small fissures. The paint then melted into these fissures. Once the metal cooled the fissure shrunk back and the paint was permentally attached to the part. I usually use an inexpensive food dehydrator to 'bake' my parts with. Temps usually stay around 100-110 degrees F. This is warm enough to both quickly dry the paint and smooth out the finish a bit. It is also cool enough to leave the part there indefinitely and not cause any problem. The dehydrators can be found at just about any big box store for 20$ USD or less. Another plus is that you can use the dehydrator to warm the paint for better paint flow as well. I have yet to have a can of paint explode from being left in the dehydrator too long... Notice I said yet??

 

[ruben]

What may have happened is thus: the higher heat, caused the metal to expand and opened small fissures. The paint then melted into these fissures. Once the metal cooled the fissure shrunk back and the paint was permentally attached to the part.

The big question I ask myself is if controlling and refining this proceeding may be the propper way to a more long lasting paint.

Cheers,
Ruben

 

[mike goldberg]

Ruben... who's paying your electricity bill, or is is a gas oven?
Cheers, mike 😀

 

[ruben]

OK, today was PAINTING DAY !

I am trying two new things. At the begining, after the premier, I doubled my customary low temperature, from around 40 centigrades to around 80 centigrades. This doesn't work, because paint dryies very fast, leaving the traces of paint instead of disolving them. So I had to go back to the 40 centigrades.

For those not used to centigrades, let's say that 40 centigrades is not only the minimum my oven can control but the maximum heat you can still touch most of the parts without burning your fingers. The parts inside the oven accumulate more heat than that the oven intends to. Backing oven, not grill nor microwave - have I remind it ?

The other change has been entering into the oven each part as soon as i finished black paint for it, instead of waiting with the parts outside the oven until all of them are painted.

Now I am going to try leaving the parts for more time than my customary overnight. I guess it will be until my wife looses her patience, and starts with the electricity bill....

Cheers,
Ruben

PS
Painting cameras is lovely relaxing. Due section at the Kiev Project.

 

[radiocemetery]

Factory car painting, home camera painting

Factory car painting, home camera painting

Hi Ruben,
I used to work in a car factory. We built Mitsubishis. The last four years that I worked there, I was working in the paint shop. After the car bodies arrived in the paint shop they were dip washed in a detergent to release oils and greases from the body shop, then the bodies were rinsed in water, then dipped in an etching tank, rinsed again, dipped in an etching primer in an electro deposit process. Well, now the car bodies went to the first oven where the primer was baked. Bodies remained in the oven about 17 to 20 minutes at 350 degrees fahrenheit. then a "surfacer" was applied. Surfacer is a high build primer. Baked again about the same amount of time and temp. then color coat and clear coat were applied and back into the oven go the bodies again same amount of time and temp. It was HOT in the paint shop.
Anyway, I tried to fake this process at home with a camera top and bottom plate. I had pretty good results. As you said the paint does get harder, but you can shift the color if the oven part of the process is overdone, we even saw this happen with car bodies if for some reason the bodies were stuck in the oven for too long. I experienced the bubbling that you mentioned. This is "solvent pop", which happens when the paint is forced to dry too quickly. The solvent in the paint does not have enough time to migrate to the surface so it "pops" and leaves a small cavity. Solvent pop usually occurs on the edge of a part where the paint film is thicker due to the film sagging, especially on a vertical surface. Hopefully the paint film is thick enough that these cavities can be sanded out.
The next time I paint camera pieces, I will allow more time for the paint to air dry, say thirty minutes and then force the rest of the drying by baking the paint at around 200-300 degrees for 15 or twenty minutes. Also, when using enamel paint, or any other paint for that matter, if the piece still smells like paint then that paint is not fully cured and has not yet become fully hardened. With enamels I have used this will sometimes take more than a week even if the paint has been baked. Paint will cure faster in a warm dry environment. Here in Illinois we do not have a dry environment most of the year so curing takes longer. I am sure conditions in Jerusalem would allow a faster cure. Hope there is some information here you can use, would be happy to answer other paint related questions.

Regards, Steve

 

[Bluesman]

Hmm...maybe it deserves mentioning that car painting shops mostly use infrared heating for baking (which is quite different from a baking oven, since the heat is applied to the paint layer/surface in a different way) and that they have huge ventilators sucking out the solvent fumes. I wud be very careful/reluctant baking paint - especially the etching primer you mention that can contain phosphoric acid - in a household oven. Yes, I know - these objects are small and cannot hold too much solvents, but still. And there´s this business with the flame point, where solvents and their fumes can self-ignite at surprisingly low temperatures if the mixture of fumes+oxygen is just right. Be careful out there. Ah yes, pre-heating the paint in the oven in a closed container is downright dangerous, and doesn´t work for all paint types either. Use a controlled water bath for such exercises, much safer.

Cheers /Richard, ex car painter too

 

[ClaremontPhoto]

I used to work in garage.

When we bought secondhand office furniture we sent it to our car body shop for painting.

I wonder if they would also paint small camera parts?

 

[payasam]

I suspect you mean primer, Ruben.

 

[ruben]

I suspect you mean primer, Ruben.

Correct, payasam, I thank you wholeheartedly since I very much need to learn technical terms to be able to express myself with more accuracy.

Thanks again
Ruben


Ps
And I invite all folks to follow payasam expample, which was well intended and accordingly phrased.

 

[Never Satisfied]

Hi Ruben, I'm another ex-spray painter and will add a few more things for you to consider in your painting project.
I would speak first to somebody at your point of purchase before you start to 'force dry' any of your paint. As a matter of course, all paint drys by some form of chemical reaction weather it is a solvent evapoative process as with nitro celulous lacquers or air dry enamlels of a chemical addative such as an Isocynate hardener as with 2 pak paints.
Although you may speed up the drying process as you've already found out with the afore mentioned 'solvent pop' not all paints like to be force dried.
You are not really up against a time deadline as in a body shop to get your job finished, so find out what the ideal application temp and drying temps are and stick to them.
Causing paint to dry too quickly can cause huge issues with loss of gloss and can cause solvents to become trapped in the substraits only to come to the surface later on and ruin your whole party. IMHO anyway, cheers Andrew

 

[ruben]

After trying to double my usual low temperature, I noticed the paint dries too quickly but the paint doesn't disolve, leaving traces of paint.

Therefore I repainted the few unfortunated parts and all others went to my usual low temperature, but I triplicated the time to full 24 hours. Apparently the paint has catched strongly than at shorter times, but as we all know, the real truth I will notice after a month.

Cheers, and Thanks,
Ruben

 

[radiocemetery]

Hi Bluesman,
Mitsubishi's paint ovens are gas fired, and yes vetilation is a huge factor. If I do small parts, I use a little toaster oven on it's lowest setting and do it outside. The system at the factory does more than 500 hundred car bodies in an 8 hour shift. I just try to adapt, have some fun, learn and refinish a previously cosmetically challenged camera.

Regards, Steve ex autoworker