Getting the best from a 3D print - Frosted Ultra Detail (FUD) material

3D printing has been getting an increasing amount of attention in the modelling press recently, however, there are two issues that commonly get raised. These are the stepping effect inherent in all 3D printing and the apparent inability to get paint to adhere to the model.

As with any model the first stage is to clean the surfaces due to the wax residue remaining from support structure they are built around (imagine scaffolding around building site). For this I use an ultrasonic bath filled with water and a few drops of washing up liquid. I normally run three or four cycles of the bath before removing the model and leave it for 24 hours to dry. If you do not possess an ultrasonic bath a light scrub with an old toothbrush and luke warm water will work as well (do not use hot water as the FUD material will warp!).

Once dry the model can be primed - for this I use a light coat of Halfords 'Grey Plastic Primer'. You will immediately be able to see the stepping effect on the surface of the model as per the picture below. Occasionally you may also find some areas where the wax residue has not been completely removed. In this case carefully remove the primer in this area and repeat the cleaning stage.

 

Once the primer coat has dried it is time to smooth any surface areas that show 'stepping'. For this I use various grades of wet and dry paper, usually starting at 600-800 grit and finishing with a much finer grade later. To gain good contact between the model and the paper I use small rubber blocks (taken from old silicon rubber moulds but a soft pencil eraser will work as well) and wrap small pieces of wet and dry around them. This method is particularly good for boilers and cab roofs. A series of scrapers will also be useful for getting into those hard to reach areas. Small flat blade screwdrivers and scalpel blades work well here. Try and hold the scraper as upright as possible, do not try to chisel away material as you will mark the surface - for the same reasons do not use files for this process!

Once you've completed your initial sanding, prime the model again. This will show how successful you have been in your initial attempt. I usually need two passes at the sanding stage before I obtain a surface finish I am happy with. Once you are satisfied with the surface finish it is time to paint your model in your choice of livery.

 

As can been seen above the stepping effect has been completely removed providing a smooth surface to apply the livery. 

A second finishing method is to apply a coat of Halfords 'Clear Lacquer' after the first priming stage. This will often remove the worst of the stepping quickly without sanding but at the expense that the fine details are not a crisp as with the sanding method. Also the sanding method has an additional advantage that you ensure that 99.9% (if not all!) of the wax residue has been removed before you apply your final paint finish.

Hopefully this short article has been useful to you in showing how to get the best from a FUD 3D print.