Handling and Cleaning

RP patterns have a range of handling and cleaning issues specific to the particular material type. Proper techniques are critical to a quality outcome in the casting process. As a general rule, the following methods apply:

Solidscape: These are the most fragile of the pattern types evaluated. Due to the material’s tendency to oxidize, which can result in a breakdown of the surface quality, it is best to cast within one to two weeks and, where shipping is involved, to pack very carefully to avoid even minor pressure on the model. Wax tree assembly using models with thin walls can be very challenging, but can be overcome by an experienced assembler. Cleaning should be done only with a citrus cleaner such as D-Limonene or PC 205. Light filing or scraping with a blade can also be done, although caution should be used on the build lines, where breakage is more likely to occur. The use of alcohol or acetone should be avoided, as either will dissolve this material.

3D InVision: Designs produced in this material are fairly strong and require only typical packaging, as might be used with carving wax. This material is relatively new on the market and good hygroscopic data (i.e., how readily it absorbs moisture) is not available, so it is best to avoid moisture during shipping and storage. Cleaning should be performed only with a citrus cleaner such as D-Limonene or PC 205. Hand cleaning can be performed with the same tools that one would use on carving wax patterns.

Envisiontec Perfactory and 3D Viper: These are the strongest materials of the group, requiring only minimal caution during shipping and assembling. Though durable, these materials are also hygroscopic; in order to maintain good dimensional stability it is best to ship and store with desiccant to prevent moisture absorption. Cleaning should be performed with industrial grade alcohol 95 percent, followed by a rapid rinse with a citrus cleaner such as D-Limonene or PC 205. Hand cleaning can be performed with the same tools that one would use on wax patterns.

Visual Inspection 

Visual inspection of patterns is a critical step in the casting process. As is the case with wax patterns, small voids and cracks can cause investment to break down (particularly in the vacuum process), later combining with the molten metal and resulting in non-metallic inclusions and/or surface pitting in the casting.

Table 1: click to enlarge

The best surface for inspection is a matte finish pattern with a medium to light color, such as is found with Solidscape. Clear patterns or those with a glossy surface are the most problematic for visual inspection. It is a good idea with these materials to incorporate finish sanding to facilitate inspection. Table 1 shows the visual inspection characteristics for the experimental group