Looks like a good system.

I like to use Microbrushes for the wheels -- they're plastic handles with foam tips that come in several sizes and are reusable.

To get paint to stick well to plastic trucks, I soak them in a solution of warm water and the cheapest unscented dish washing liquid the grocery story sells. Rinse in warm water and let them dry on a paper towel or newspaper overnight.  This takes off the greasy mold release and vastly reduces chipping.

Rich,

Thanks for the step-by-step!  Even a novice like me should be able to achieve good results using your techniques.

To get paint to stick well to plastic trucks, I soak them in a solution of warm water and the cheapest unscented dish washing liquid the grocery story sells. Rinse in warm water and let them dry on a paper towel or newspaper overnight.  This takes off the greasy mold release and vastly reduces chipping.

I never thought of there being a residue on the plastic.  Makes sense though now that you have pointed it out.  Thanks for the tip!

Could be your freight cars are painted when they arrive, so the maker has already prepped those castings. Trucks also use fairly complex molds, and the casters probably keep them well greased-up, as it were. Both plastic and metal wheels also show up with a coating.

I always clean any bare plastic (or metal) before painting.

Once you have dropped a plastic part into a detergent bath and watched the mold release float to the top, you'll never skip that step again.

Nice. I've found that using wheel masks from American Model Builders, Modelers Choice, or MinitueMan Scale Models help me a ton.

Plastics with low surface energy such as Delrin, PP, TPO are relatively easy to pop from molds so the common practice is to blend the release agent, oftentime wax products, directly into the plastic melt. The release agent is throughout the part not just on the surface in these applications. That makes cleaning so much more important when trying to get good paint adhesion. I suspect trucks are molded with release-mix plastic melts because of their small size, detail, and production cost in volume.

That goo floating in your dishwater soak, look kinda waxy?

LK&O-

Before I get into my question let me first say that you deserve kudos for taking a specialized skill set and applying it so well to our hobby.  Without a doubt you are the person I see on these boards who provides the most unique and helpful insights into issues that other modelers have.  Thanks for being around and for sharing!

Now to my question:  I am prepping another set of trucks and wheels on a hopper car for final treatment and decided to put them in a bath of denatured alcohol to see what it did.  Will this work?  I ask because I have a ton of it, it's cheap, and it's sitting underneath my workbench and doesn't require me to go upstairs and take from the kitchen every time I want to use it. 

thanks again for your help!

~rb

I am prepping another set of trucks and wheels on a hopper car for final treatment and decided to put them in a bath of denatured alcohol to see what it did.  Will this work?

Firstly, thank you very much for the compliment. Being such a noob modeler I feel I have nothing to add to ya'lls train discussions. But when it comes to paint and surfaces to be painted well I know a pinch more about that!

There is an important distinction between detergents (earlier mentioned dish soap) and solvents (your alcohol). Detergents emulsify contaminants while solvents dissolve contaminants. Emulsifying is a relatively slow process hence the reason your wife lets dishes soak before washing them. Solvents on the other hand work relatively quickly depending upon their solvency strength relative to the containment. Therefore, soaking is not as advantageous for solvents.

To muddy up the picture further, solvents are picky about what they will dissolve. Generally they are most effective at removing organics - petrochemical products. An example would be how well lacquer thinner cleans off grease and oil but is almost useless at removing soap scum. This finickiness of solvents makes it challenging to say what solvent will dissolve what containment without testing. And we have no way of knowing what mold release was used in the manufacture of the trucks. Could be wax, could be an oil, could be a silicone. Who knows. One thing is for sure - your plastic trucks are organic (began life as oil) so many solvents will dissolve them as well as the contaminants. Don't soak plastic in any solvent.

Detergents don't dissolve things, they lubricate the mating surfaces of the containment and the object causing virtually any containment to "lose its grip" and float away in the water. Ever notice how slippery detergents are? That is what makes them work. Because detergents lubricate uniformly they are far less picky about what they will remove hence their widespread use as universal cleaners. Only highly hydrophobic contaminants are resistant to detergents (hydrophobic and hydrophillic are another discussion later :))

One of the most universal of all solvents is n-Butyl Acetate (commonly used in paint reducers). It is available at Home Depot and Lowes in their paint department. With it you can dissolve many, many organic contaminants. Alcohols are some of the most finicky of solvents. They clean some things nicely and others not at all. Rubbing alcohol should be avoided at all costs since it contains an oil.

I would suggest the dish soap soak and wash (hot hot water is best), rinsed very well, dried completely, followed by a wet wipe of n-Butyl Acetate just prior to paint as a very effective mold release cleaning process. Another option, and also a very good universal cleaner, is aerosol foaming window cleaner with amonia. These products are both a detergent and a solvent in the same can. Great universal cleaners. 

Thanks for the tip LK&O.  I ended up taking the plunge and soaking my wheelsets overnight in denatured alcohol prior to your reply (no one has ever accused me of being patient) but it doesn't look like I've done any permanent damage at this point.  I'm going to give an application of paint a try and see what happens.  If it works, I'll report back.

That being said I'll follow your advice on the next set of trucks.  Thanks for taking the time to reply!

~rb

Great little tip sheet on solvents and detergents LKO, thanks! Printed this out and put it in my tips and ideas binder. I swear I'm learning something everyday in these forums.

those look great nice job.

I just went thry all my rooling stock about a year ago and added weathering to the stock "gloss black" trucks and "chrome wheels". Hope you dont mind If I can share what I did after a fellow modeler (named Jerome) tipped me off to a fast and easy way to do this with an air brush.

I first took the trucks off of the cars then removed the metal wheels. Painted the wheels with a floquil weathering pen (rust pen) Now paint the trucks floquil grimy black. Then mist the trucks lightly with a rust color. you can also mist the wheels with the airbrush using both the grimy black and rust to give the wheels a 2 or 3 tone color. I think I was able to do about 10-15 cars an hour untill I made my way thru all my 100-120 freight cars.

so many ways to weather and always enjoy seeing new ideas, thanks for sharing!

Regards

Trent