Painting an Aluminium Chassis

[RoadrunnerOZ]

There are paints designed for use in harsh environments, specifically aimed at aluminium railings - you may need to brush coat rather than spray if there’s too much wind but spraying is preferable - a good clean immediately before painting is essential - there are often surface prep products applicable to the chosen paint that can help. Clean the cured primer surface before applying topcoats. Better still unbolt the railing and paint it out of the wind and salt.

 

[scott2000]

Thanks.. Lots of good info

 

[Gold]

How stinky is aerosol etch primer and automotive primer and paint?

I have a small workshop with a door to the hallway as ventilation. I’m planning on painting a few 7” x 5” x 2” project boxes. I can’t annoy the neighbors too much.

 

[scott2000]

How stinky is aerosol etch primer and automotive primer and paint?

Way up there in the stink . Isocyanates are no joke either

 

[k brown]

If you don't need a high-gloss, super smooth finish, a low-to-no stink/VOC finish is good old fashioned yellow shellac (bonds well to almost anything) followed by acrylic paint (I use artist acrylics rather than house paint), top coated with clear water-based urethane, which is very tough stuff; even recommended for floors.

I stipple on the acrylic coat with a brush, which leaves a slightly bumpy surface that helps resist scratches. Artist acrylics are even available in metallic colors.

 

[Gold]

If you don't need a high-gloss, super smooth finish, a low-to-no stink/VOC finish is good old fashioned yellow shellac (bonds well to almost anything) followed by acrylic paint (I use artist acrylics rather than house paint), top coated with clear water-based urethane, which is very tough stuff; even recommended for floors.

I stipple on the acrylic coat with a brush, which leaves a slightly bumpy surface that helps resist scratches. Artist acrylics are even available in metallic colors.

I bought a small airbrush and small airbrush compressor years ago, kind of in anticipation of this. Maybe it’s time to learn how to use it.

 

[RoadrunnerOZ]

Automotive wheel clear-coat is very tough and is readily available in spray cans - I’ve used the VHT stuff on several products - it resists chipping, cracking, scratching and fading (some clear-coats go yellow with time). This is the high temp engine version:
https://autobarn.com.au/ab/Autobarn...oss-Clear-High-Heat-Coating---SP145/p/DI04794

 

[scott2000]

Always impressed with VHT. A secret weapon for so many things. Their satin caliper paint is like magic and their can spray tips are really nice flowing...

 

[RoadrunnerOZ]

VHT seems to work from the can just as well as a low airflow spray gun. For my detailed work I use a little airbrush compressor, for the bigger jobs I have rigged up a regulator and full air filter with standard air fittings to run off my bigger compressor - I mounted it all in an aluminium tool case about the size of a briefcase, only deeper. You need well filtered air for spraying - no moisture or oil vapour from the compressor. The airbrush compressor fits in the same case with all the tiny hoses, guns and attachments. I can even run the airbrush heads from the larger compressor - I made up adapters to fit Nitto.

 

[scott2000]

For my detailed work I use a little airbrush compressor

How much overspray is there actually with these? I've been tempted to look into an hvlp setup for doing some interior trim spraying if possible. How does the finish lay down??/
any chance to share your small air brush setup?

I just repaired a section of scratched up bath vanity for a friend that obviously wasn't able to be moved to a garage...
The vanity company was secretive about their proprietary "scratch resistant" product and the regular acrylics don't get as black.
I used the VHT satin from a can on it just for kicks... It was pretty good and the color was just about dead on, but spraying inside was a bit nerve racking. They were out of town though.... I thought about just putting an anodized piece of aluminum if things didn't pan out....

To be able to do some trim spraying would be sweet. I can hand paint the hybrid latexes and sand between coats and get it nicer than a lot of guys who spray but it's time consuming....

 

[RoadrunnerOZ]

There is always overspray - for small items I made a little corrugated plastic sheet house - the product is called Corflute. At the back of the little box I put a 150mm computer fan with a particle filter panel in front of it feeding to an aircon tube 150mm dia. Running to the outside world. All available from the local hardware store - although the Corflute I had came as a leftover from a big car show I did the setup for which was used as sign and display panelling. You can cut it with a trim knife and use duct tape to join the panels. The pipe fits to a standard 150mm duct flange fixed to an air box behind the fan. I have pulled it apart and flat-packed in a box for the moment or I’d send you a photo but I got the idea from this:


I used a turntable made from a rotating pot plant turntable base - $7 from Kmart. The fan/flange box was also made from Corflute and I used high brightness white LED striplight for all round illumination.
The airbrush case:

 

[RoadrunnerOZ]

HVLP painting has not as fine a finish as conventional spraying. The overspray and subsequent waste in conventional spraying for small items - items that are narrower than the spray fan for example like railings and any metal strips - this has led to the introduction of the high volume low pressure gravity fed system but the downside is a more orange-peel type finish due to the larger paint droplets. LVLP gives the best of both worlds with a finer atomisation of the paint by using smaller air holes - a compressor with a lower free air displacement rating than the HVLP can be used and the end result is a much better finish.
The high volume and low pressure referred to in HVLP are related to air volume required and pressure at the atomising aircap.
Airbrushing is far more controlled as far as directing the paint/air flow but you still get overspray so air extraction is really advisable (for any spray painting). HVLP gives 65% paint on the job but this leaves 35% overspray losses, same with LVLP, conventional has much lower paint-on-the-job figures. With any sprayer the higher the pressure fed to a gun the finer the spray and more overspray losses. Most guns these days have a pressure regulator to bleed off excess air pressure and paint quantity is controlled by the trigger.

 

[scott2000]

not as fine a finish as conventional spraying

Had to look that up. Not the same as airless. Interesting...

 

[RoadrunnerOZ]

Had to look that up. Not the same as airless. Interesting...

Airless spray systems force paint from a high pressure pump through a tiny nozzle. When the paint jet hits the air at high speed it breaks and spreads into tiny microscopic droplets. Some airless guns use air assisted low pressure side fans to soften the edges of the spray pattern. These units are quick and easy to use but result in a lot of overspray. A good quality professional unit typically feeds paint to the tip at between 1500 and 3000psi, the handheld domestic units without the remote pump system can be between 800 to 2000psi

 

[Gold]

Automotive wheel clear-coat is very tough and is readily available in spray cans -

I ran across that stuff. Good to know. I'm starting to kick around ideas for new faceplates for my console. A different project. They are hand stamped now but that is time consuming and harrowing as one mistake and you are done.

There are $30 sandblast guns on the bay. I think I'll pick one up. I'm thinking beating the crap out of the aluminum with steel grit for texture. Then clear coating it. Then marking it with paint and a vinyl cut stencil. Then more clear coat on top. Might look cool.

 

[Gold]

I ran across this paint brand. 620-1431 Seymour MRO Industrial Primer, Light Gray (17 oz) - Seymour Paint

The primer says industrial strength and low VOC. The enamel doesn't say VOC but I think I might give these a shot. There is a Dark Green which I like.

 

[RoadrunnerOZ]

I ran across this paint brand. 620-1431 Seymour MRO Industrial Primer, Light Gray (17 oz) - Seymour Paint

The primer says industrial strength and low VOC. The enamel doesn't say VOC but I think I might give these a shot. There is a Dark Green which I like.

I don’t think it’s designed for aluminium is it?

 

[RoadrunnerOZ]

I ran across that stuff. Good to know. I'm starting to kick around ideas for new faceplates for my console. A different project. They are hand stamped now but that is time consuming and harrowing as one mistake and you are done.

There are $30 sandblast guns on the bay. I think I'll pick one up. I'm thinking beating the crap out of the aluminum with steel grit for texture. Then clear coating it. Then marking it with paint and a vinyl cut stencil. Then more clear coat on top. Might look cool.

You need pretty good protective gear for using these - we used an industrial sandblaster where I used to work in the auto shop, there were special steel mesh gloves and these were mounted into the lock-down top visor hood of the machine. These things will take you down to the bone and the flying blast particles go everywhere including your eyes. They go through a ferocious amount of blast grit - our machine had a recovery hopper at the base which then fed the grit back into the system. Aluminium will disappear at an alarming rate.

 

[Gold]

I don’t think it’s designed for aluminium is it?

I guess not. It just says metal. The etching primers they have say they are for aluminum. Not VOC though.

You need pretty good protective gear for using these - we used an industrial sandblaster where I used to work in the auto shop, there were special steel mesh gloves and these were mounted into the lock-down top visor hood of the machine. These things will take you down to the bone and the flying blast particles go everywhere including your eyes. They go through a ferocious amount of blast grit - our machine had a recovery hopper at the base which then fed the grit back into the system. Aluminium will disappear at an alarming rate.

I've seen small table top sand blast cabinets. I figured I'd start with something like baking soda in a mostly sealed plastic bin.

 

[RoadrunnerOZ]

Like this one - the holes at the front lead into the gloves: