Painting models with hardware store spray paints.

As usual, this is an opinionated site, these are my views. you don't have to agree with them.




We have all seen the posts on various forums and Facebook groups.


Help i don't know what happened to my paint? I used brand X paint and Brand Y clear and this is what it looks like.


The pictures normally go on to show a finish that has lifted the undercoat and makes the surface look like a dried lake bed. At this point the original posted is normally bombarded with 50 different replies, some of them actually trying to offer good advice as to how to avoid things like this in the future. The others feel a need to comment from their Godly positions and inform others that ' Brand X is garbage' or ' that's not made for models'.


All of these comments are simply stated, Horse shit.


Paint is paint, its pigment with a carrier or solvent. From dollar store rattle cans, to 50 cent craft paint, to nail polish, all the way to model specific brands aimed at the hobby. It all serves the same purpose, cover something with the color of your choosing.


For some, the cheaper option is more viable to them as they try to make ends meet and also continue with their hobby. Those of you with unlimited budgets or getting paid to build via commission jobs can continue paying the higher priced hobby specific manufacturers and there is nothing wrong with that. This article is for those that don't want or cant afford that extra money layout and still want to build decent finished models.


I will tell you now, the most common reasons for 90% of the failed ( lifting ) paint jobs i see can be boiled down to 3 different problems.


Product incompatibility:

If you are using two different types of paint, ie: Rustoleum enamel color coat and a clear coat that is acrylic lacquer. The Xylene in the acrylic clear is 'hotter' than the thinner in the enamel, this will cause the clear coat to soften the color coat all the way down to the plastic and crack ( or lift ) the finish.

You can prevent this by making sure the products you use are both from the same paint family. Enamel color + enamel clear= happy times, Acrylic enamel color+acrylic enamel clear = happy times

Now there are two caveats to the above. The first is 2k automotive clear. This is harder to find in spray can form but it does exist. You can spray 2k clear over basically any color coat and get an awesome shine and gloss. The problem is, it is expensive compared to other spray clears and once you activate the hardener in it, it has a very short shelf life. sometimes as little as a week. The second caveat is Future/Pledge or whatever else they decide to call it this week. Now is normally the time that the paint Gods start throwing lightning bolts again because, how dare i recommend a floor product to use as a clear coat, in 10 years it will yellow, it should be used on floors and not models. Yeah whatever....the bottom line is that its been used for decades in every genre of model building. It has made its way into countless issues of Scale Auto Enthusiast, I personally have used it for over a decade ( still have not seen this yellowing they harp on about ) . It is self leveling, It can be sprayed, brushed or even dipped to offer a budget high gloss shine without worrying about what it will do to the color coats.


Not knowing the recoat window:

Pretty much every paint manufacturer lists what is called the recoat window on the directions right on each can.

example:

DRY & RECOAT Dry and recoat times are based on 70°F (21°C) and 50% relative humidity. Allow more time at cooler temperatures. Dries to the touch in 20 minutes, to handle in 1 hour and is fully dry in 24 hours. Apply a second coat or Clear Coat within 1 hour or after 48 hours
So what does that tell you?

Providing your base temperature is at least 70f and your relative humidity where you paint is below 50%, You would be able to touch the part within about 20 mins ( but not handle it ) after an hour you can actually pick it up and handle it and after 24 hours it is sufficiently dry enough to work on. BUT....the paint is not fully cured yet. The paint is not fully cured until after the 48 hour mark under ideal circumstances. Now for the last line of the instructions...this is the important one where so many screw up because either they don't read or they are in a hurry and try to cut corners. If doing either more color coats or adding a clear coat, you can do so either within 1 hour of the last coat of color, if you miss that hour, you will have to wait until after 48 hours to either add color or clear. during the time in between, the paint is vulnerable as it is in a 'partially cured ' state. the addition of more paint or clear will disrupt this curing and soften the underlying layers of paint resulting in disaster.


Each manufacturer has different instructions for recoat times, read your cans before you begin so you have a solid plan in place to have the best chance at success.


Topcoat applied too heavily:

Lastly, Learn to apply your top coats or clear coats by building up lighter mist coats until you get the depth you want. It does take more time but it also eliminates the risk of flooding the underlying paint with excess solvents that are in the upper coats, thus cutting down on the amount of problems you are likely to have.


Avoid the 'wet coat' syndrome that used to prevail in the hobby. ( we all remember the 2 mist coats then 3 wet coats and cross your fingers to hope it does not run ) If you are using a spray can, you can get the same high shine finish with 6 mist coats as you can with 2 mist and 3 wet. the key is to actually turn it into a continuous paint session. If you start with the main body give it a good mist coat shooting for about 50% coverage, set it down and go to your other parts like the hood, doors or whatever else you are painting, as soon as you are done with them, pick up the body again and start the process over. after 5-6 50% coverage mist coats, you should have even coverage and depth. if it is not shiny enough for you then feel free to add a few more rounds in the same manner.


I will tell you outright, i have not used a spray can to paint a model in years, but i have used all of the above listed paints. I frequently decant them into cups and shoot through my airbrush which gives me more control over the amount of both air and paint that is released at any one time. Same principal, different vehicle to get there, that's all.



Now for those of you that have read through the entire article, Thanks for taking the time.


The next time you see someone say ' That paint is garbage' or 'throw that paint in the bin' . Remember they only have their views because they could not figure out how to make that brand do what they wanted. Take it as a personal challenge to figure it out and do better.