Certainly easier
Painting an Aluminium Chassis
- Thread starter cpsmusic
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Have you seen the collapsible crates
For critical paint jobs, like this antique scale restoration, I’ve made a temporary paint booth out of cheap wood and plastic sheeting, mostly to keep dust off parts while drying. Antique Balance Scale Restoration
Nice job on the scale restoration
I spent 5 years working for a company that specialises in restoring luxury Supercars to factory standards. Ferrari, Lamborghini, Aston Martin, Rolls Royce, Bentley, McLaren, De Tomaso, Mercedes, Porsche and many other marques. These standards are exacting and require attention to detail not just in paint finish, thicknesses and composition but also in chassis and body dimensions and components, glazing and trims right down to the bolts and nuts. One of the most rewarding jobs I have had as I was also picking up, assessing, detailing and delivering these cars for the customers while at the same time organising car shows and Concours and doing the audio for them as well.
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I painted the box. There is definitely a lot of room for improvement. I have some rough spots and the coat doesn't seem very even. I think my initial coat was too heavy and it was all downhill from there. One thing I figured out a little late is that the first time you use the can don't point it at the object to be painted. Make sure what's coming out is mixed well and not splattering. I got some splatter and spots that didn't come out. I tried sanding the rough spots and repainting. It worked somewhat but not that great. Hopefully the next one will be better.
Don’t start or finish the spray run on the job surface or you get splatter - starting just before it points to the job edge starts the uniform spray pattern in time for it to be even when it hits.
I always spray L-R, R-L, L-R, R-L in even strokes stopping and restarting the spray for each change of direction outside the job periphery and ensuring the can is vertical for flat surfaces and dropping down for the next run line enough to overlap evenly and ensuring each line is parallel.
If doing a box (5 sides) you need to tilt the can so it’s at 45° down to the top edge for that run and then rotate the can nozzle right to start the left edge and rotate to continue across the face flat-on and then rotate nozzle to the left for the right end - then tilt can again upwards for the bottom edge - its best if the box to be painted has an air gap between it and the spray box back so you don’t get blowback. (It’s not good to spray down onto a job as the paint will stop flowing.)
If you paint edges and face of a box separately the overspray will create a dry dusty finish on the surfaces not being painted directly. For project boxes with a flat lid I do all surfaces of the box section (5 parts) in one set of strokes, then the lid (which for those boxes is the base)
I always spray L-R, R-L, L-R, R-L in even strokes stopping and restarting the spray for each change of direction outside the job periphery and ensuring the can is vertical for flat surfaces and dropping down for the next run line enough to overlap evenly and ensuring each line is parallel.
If doing a box (5 sides) you need to tilt the can so it’s at 45° down to the top edge for that run and then rotate the can nozzle right to start the left edge and rotate to continue across the face flat-on and then rotate nozzle to the left for the right end - then tilt can again upwards for the bottom edge - its best if the box to be painted has an air gap between it and the spray box back so you don’t get blowback. (It’s not good to spray down onto a job as the paint will stop flowing.)
If you paint edges and face of a box separately the overspray will create a dry dusty finish on the surfaces not being painted directly. For project boxes with a flat lid I do all surfaces of the box section (5 parts) in one set of strokes, then the lid (which for those boxes is the base)
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That’s great info. Thanks!
The big difference between airbrush or spray gun and a can is that the airflow that carries the paint can be started before the paint is introduced in a dual action spray gun - the air is already flowing as the paint control needle valve opens so you don’t get “start” splattering - with a can the propellant airflow starts picking up paint immediately so the early part of the flow is droplets until it’s moving fast enough, sufficient to atomise the paint.
When I’ve airbrushed scale model parts I’ve used a tiltable gravity feed pot to enable spray from any angle for awkward 3D parts - the siphon feed requires more air pressure as it relies solely on that flow speed to draw up the paint.
When spraying car panels the first pass I make is usually just air on half trigger to blow any settled dust particles which can settle - even in a negative pressure spray booth after wet wiping the surface with lint-free cloths. The good thing about the booth is the overspray is carried away from the job and doesn’t settle back on the drying paint. Same as a portable box with extraction fan at the rear or top rear.
When I’ve airbrushed scale model parts I’ve used a tiltable gravity feed pot to enable spray from any angle for awkward 3D parts - the siphon feed requires more air pressure as it relies solely on that flow speed to draw up the paint.
When spraying car panels the first pass I make is usually just air on half trigger to blow any settled dust particles which can settle - even in a negative pressure spray booth after wet wiping the surface with lint-free cloths. The good thing about the booth is the overspray is carried away from the job and doesn’t settle back on the drying paint. Same as a portable box with extraction fan at the rear or top rear.
I’ve discovered what you say about spray cans. I’ve had a feeling that using an airbrush is no easier and probably harder to get right initially than a spray can. That’s why I haven’t attempted it despite having the equipment. I might take a pause to play with the airbrush on scrap material. Once I’m up to speed attempt something I want to use.
It’s good to try airbrushing on small cardboard boxes as in jewellery box size bluetacked to a backboard to get a feel for corners and edges on a 3D object.
With all your pointers I’ve worked up the courage to try using an airbrush. After some digging around I was able to get the airbush, regulator/moisture trap and compressor hooked up.
I’m not sure if the regulator was broken when I got it or I did something. I wasn’t getting any airflow through it. I figured out the actuator attached to the screw top wasn’t making contact with the diaphragm that regulates the airflow. I stuck a couple of washers on the diaphragm and put it back together. It’s passing air now but I think it should be more finely adjustable. Good enough to start.
Below is a second attempt at the box. It’s much better. The overspray may offend you but moving further away and starting the spray further away was worth the mess. I’m more concerned with the work piece than the mess at this point.
Attachments
Looks ok - bit hard to tell with reflected light though. How is it dry - even?
It is drying evenly. I had it done and had let it dry for over 24 hours. I picked it up and it wasn’t dry. I got fingerprints on it so I resprayed it. I’m going to let it dry at least 72 hours before touching it. The coat is even on most of it. The bottom and top are even. There are a few specs of dust here and there and on one side there is paint build up in one place.
scott2000
Well-known member
Make sure you're not going astray too far of manufacturer recommendations... Asking for all kinds of trouble with adhesion,pops..etc if messing around with recoat time windows...maybe having to scuff...etc....... May not matter...
The manufacturer recommendation is recoat either within an hour or after 24 hours. Seems okay.
Dry times are always screwed up by ambient conditions - in winter the paint may never properly cure if the temperature is too low until the temperature is raised enough. There are some low temperature cure paints from companies like PPG (used on Ferrari) water based baked at 100° (room temp here on a normal summer day) instead of 150° (65°C) for most paints - it pays to check before applying any heat.
If it’s cold when you paint you can also get surface “frosting” where moisture is attracted from the air and settles on the fresh paint causing it to mar the finish. This is due to the cooling effect of evaporating solvents in moisture laden air.
In the workshop I worked in we used gas heated temperature controlled booths and the work to be painted was sprayed in the same booth with negative pressure - heat turned on once spraying finished.
I also built an IR rail mounted 3D cantilever baking system in a cold booth which uses a wavelength that heats the paint from just below the surface rather than from the surface inward (no paint boiling) with laser targeting and surface temperature monitoring. The amount of emitted IR controlled by the pulse width of chopped high voltage DC - this allowed plastic parts (like bumper bars) to be cured without heating up and warping which happens in a baking oven.
For home baking metal parts a small low speed fan heater can be used - once the surface has properly tacked off to prevent dust being carried onto and sticking to the job.
Radiant coil heaters (unless controlled IR) can get the job done unevenly and cause blistering unless at a distance and will melt plastics.
I have a temperature controlled heat gun that I sometimes use - these were used in the workshop for curing spot paint work - the drying movement pattern the same as spraying.
Be careful with hairdryers if they’ve been used around hairspray - they will carry tiny dried spray particles that will stick to your paint.
If it’s cold when you paint you can also get surface “frosting” where moisture is attracted from the air and settles on the fresh paint causing it to mar the finish. This is due to the cooling effect of evaporating solvents in moisture laden air.
In the workshop I worked in we used gas heated temperature controlled booths and the work to be painted was sprayed in the same booth with negative pressure - heat turned on once spraying finished.
I also built an IR rail mounted 3D cantilever baking system in a cold booth which uses a wavelength that heats the paint from just below the surface rather than from the surface inward (no paint boiling) with laser targeting and surface temperature monitoring. The amount of emitted IR controlled by the pulse width of chopped high voltage DC - this allowed plastic parts (like bumper bars) to be cured without heating up and warping which happens in a baking oven.
For home baking metal parts a small low speed fan heater can be used - once the surface has properly tacked off to prevent dust being carried onto and sticking to the job.
Radiant coil heaters (unless controlled IR) can get the job done unevenly and cause blistering unless at a distance and will melt plastics.
I have a temperature controlled heat gun that I sometimes use - these were used in the workshop for curing spot paint work - the drying movement pattern the same as spraying.
Be careful with hairdryers if they’ve been used around hairspray - they will carry tiny dried spray particles that will stick to your paint.
