Prototyping a product is an iterative process, and the result of most prototyping activities is rarely an aesthetically pleasing model. However, once the product is ready to be revealed to the world, whether through a crowd funding campaign, to an investor, your product idea submission, or photo shoot, the prototype needs to look like the finished product to get the serious attention it deserves. Pre-production prototypes of most products are made from 3D printed or other materials that are in a raw color and they need to be painted to give the product the desired look and feel. Here are the techniques and tips that the Edison Nation product design team uses to give our products a great paint finish.
Painting a prototype in the Edison Nation shop is only done in the latest stages of the process. It can take from a couple of days to a week or more depending on the material being painted, the number of colors, and the number of components to be painted. Since the time commitment is so high, painting is only done at the end of the process. Painting prototypes too early in the process is also risky in the sense that paint buildup can ruin part fit tolerances and jam mechanical mechanisms. So it is best to wait as long as possible to paint a prototype.
Before doing any painting, there needs to be a proper place to do the work. Painting should always be done with proper ventilation and respiratory protection. The Edison Nation shop is equipped with a paint booth with filtration and an exhaust fan and the team always uses respirators when shooting paint. This system may be outside the budget for most individual inventors, but there are plenty of plans for low cost Do-It-Yourself (DIY) booths on maker websites. Alternatively, painting can be done outside during nice weather. In either case, investment in respiratory protection that fits the paint being used is a must. It is also smart to use rubber gloves to prevent paint from getting on your skin.
In addition to a good place and proper safety equipment, the painting area needs to be outfitted with preparation and cleaning supplies. Sand paper is a must for preparing models, and a selection of paper from 100-800 grit is perfect for most applications. A way to hang up the pieces being painted will help to cut down on imperfections. The Edison Nation paint booth has a wire and a set of S-hooks to hang the painted parts while they are drying. Clothes hangers and binder clips are also helpful in this regard. It is also important to have cleaning supplies in the painting area. Paper towels are a must have as well as paint thinner or other solvent to remove the paint from your applicators after you are done.
Successful painting is all down to preparation, and this means creating a smooth and clean surface to apply the paint. Some materials need to be prepped more than others. Machined metal or plastic prototype pieces may only need some light finish sanding for a smooth finish. Models made from a 3D printer typically require more work as they have small steps in the surface from the layers created in the build process. This usually requires heavy sanding of the layer marks with a low grit sand paper and further sanding to smooth the surface with progressively higher grit papers. In most cases, it is not worth going to a finer grit than 600 for most painting.
There are many ways to deliver paint to a model, and the savvy prototyper knows which and how to use each style to create a great looking finish. There are three main delivery techniques that get used in the EN shop: spray paint, air brush, and paint brush. The main considerations when choosing one of these methods is the amount of area that needs to be covered, the speed at which it needs to get done, the desired surface finish, and the choice of colors. Spray cans have the best coverage, fastest drying time, zero setup and cleaning time, and a decent choice of colors, so they get used the most in the EN shop. When we need to do fine detail work, or lay down translucent paints where coverage thickness is crucial, the air brush is the desired tool. Paint brushes only get used if we are doing really fine detail or touchup work where a propelled paint solution will not work.
For a typical spray paint job in the EN shop, the work flow is pretty standard each time. The part is prepped by sanding out the rough edges and imperfections. Then the part is cleaned with Bestine thinner, and a coat of matte grey primer is applied. This gives the first indication of the surface finish. If there are any pits or grooves left, they are filled with a modeling putty and re-sanded. The part is re-primed and left to dry. The primer fills the rest of the small gaps, and it gives the paint a good surface to grip to. When the primer is setup, any areas where paint is not wanted is masked. The part is cleaned with Bestine again, and the paint is applied to the part. Each time paint or primer is applied it is done with broad sweeping strokes that are applied about 8 to 12 inches from the part to slowly build up the paint without causing a run. The first coat of paint is light, further coats are applied heavier to get a uniform color on the part. Once the color is left to dry for a day, the parts are given a clear coat. The clear coat gives the part a wet looking mirror finish that is usually a good representation of an injection molded part, and it gives the paint job some protection from getting dinged during use. The clear is applied light for the first coat and heavier in subsequent coats until the desired finish is achieved.
One of the keys to using spray paint effectively is to find a brand that has the colors that you need for the project and stick to that system of primer, paint and clear. The EN team has found that automotive spray paint like Duplicolor Perfect Match is great system that dries fast and is durable. However, it is only available in automotive colors that match a specific model of car or truck. When a wider selection of colors is needed, the Montana Gold and Montana Black line of artist spray paints is used with their clear coat.
At some point, the object of prototyping a product is to make a looks like, works like model to use to get investors, make a crowd funding video, or send to a factory for sourcing. The best way to get a product prototype to look great is to give it a professional looking paint job. While it may take upwards of a week to get it right, the tools and equipment need not be expensive and it can make all difference in getting your invention idea sold.