SPECIAL PROJECT:
GRINGOTTS GOLD BARS
BASECOAT
Universal Studios Orlando needed hundreds of gold bars for the Harry Potter and the Escape from Gringotts attraction. The beauty of Spectra Chrome is spraying chrome of any color over any substrate – the bars were 3D-printed; and making them look like real gold was right in our wheelhouse.
The raw 3D-printed bars were rough and textured, and had a number of pinholes. To get them ready for basecoat; the bars were first sanded, degreased, primed, and then sanded again; as shown in the Filler and Sandable Primers section. Surface prep can make all the difference in how reflective the final finish can be.
We basecoated hundreds of bars over several days, using different spray gun accessories – some of the bars were sprayed with the Harbor Freight HVLP paint gun and stock hopper, and some were sprayed using the Sagola Disposable Paint Cup (DPC) system. At Spectra Chrome, we use the DPC system all the time. It makes cleanup much easier, and allows you to spray from any angle – even upside down.
After the basecoat was applied, each bar was allowed to air dry overnight in the warm space (with the heater turned off). The next day, the drying process was completed by turning the heater on and bake-drying; as described in the Drying the Basecoat section.
Keep in mind – it is impossible over-dry the basecoat. Basecoated parts can be left for days or even weeks before you apply the silver. However, it is important to keep your basecoated parts free from dirt and contamination. Ideally, keep them in your warm space where they are protected.
SPECIAL PROJECT:
GRINGOTTS GOLD BARS
METAL SPRAY
After the bars have dried thoroughly, it is time to apply the silver layer. We mixed the silvering chemistry as described in the Mixing Metal Spray Products section.
Always spray in a well ventilated area. In the video, we show metalizing in front of our Open-Face Spray Booth (OFSB), which is coming soon.
The day of metalizing, the heater in the warm space was turned on low; so the temperature inside reached at least 75°F (but not exceeding 110°F) and the humidity dropped below 50%.
The “raw” metal spray layer is especially vulnerable to humidity. Pre-heating the warm space allows us to immediately transfer the freshly metalized parts into an ideal low-humidity environment for protection after spraying.
Each part was taken directly from the warm space, and then sensitized, rinsed, metalized, rinsed, and blown dry.
Remember, when spraying sensitizer and metalizing solutions, always “wet” the entire surface area of the part with solution as quickly as possible. The top and sides of the gold bars will be the most visible when displayed – therefore, when sensitizing and silvering, we start the application on the top and sides, then move quickly around to the back. After the silver was applied, each bar was returned to the protection of the warm space.
Although not shown, each bar was then sprayed with a “glossy/frosty” topcoat layer to protect the raw silver until it is time to add the gold color. The “glossy/frosty” bars were left to air dry in the warm space (with the heater turned off) overnight.
SPECIAL PROJECT:
GRINGOTTS GOLD BARS
TOPCOAT
After air-drying overnight, our “glossy/frosty” bars are ready for topcoat. By mixing combinations of Spectra Chrome color tints, you can easily achieve any color – these bars will be tinted to look exactly like rich, 24kt gold.
We prepared two separate mixtures of Topcoat 311 – as outlined in the Topcoat Mixing Procedure section.
TOPCOAT 311 (NO COLOR)
First, we prepared (2) volumes of mixed Topcoat 311 (no color) for use as the final clear. The mixture was poured into a DPC liner and set aside.
TOPCOAT 311 (GOLD COLOR)
We prepared an additional (3) volumes of mixed Topcoat 311 to be used as our gold color. The mixture was poured into a separate DPC liner, and color tints were added. The gold color was created by adding (6) drops of yellow tint, (3) drops of orange tint, and (2) drops of red tint to our mixed Topcoat 311. This creates a beautiful 24kt gold look that perfectly matches the real 24kt gold plating of our sister company, Gold Effects.
In the video, our Open-Face Spray Booth (OFSB) – coming soon – provides the ideal ventilated area to apply the topcoat.
The 24kt gold look is achieved by applying (3) light “dusty” coats of Topcoat 311 (gold color) with no flash time in between. The goal is to build up the color intensity slowly with each additional layer until we arrive at a rich, deep 24kt color. It is important to use multiple light coats applied gradually, to allow for fine control of the color – if too much gold color is applied too heavily, the final appearance may lean toward orange.
Once the desired gold color is achieved, we immediately return each bar to the warm space (with the heater turned off) for protection as they await the final layer of Topcoat 311 (no color).
To complete the finish, we will apply one last layer of Topcoat 311 (no color) as a final protective coating. We swapped in our reserved Topcoat 311 (no color) by following the lacquer thinner spray gun cleaning procedure, as shown in the Topcoating Practice Tiles section.
Failure to clean the residual gold color in the chamber could cause additional color to be applied; and change the resulting karat of the gold finish.
We complete each bar with a final coating of Topcoat 311 (no color). This final layer “melts” any dry-spray areas together. The bar on the top right has not yet been coated with the final layer of clear. Notice how it has a dry “frosty” appearance; which is perfectly normal during the color application.
The bar on the bottom left has received the final layer of clear, and the perfect mirror reflection has been restored. Beyond the aesthetics, this final coat also provides maximum scratch resistance and UV protection; to ensure the vibrant gold shine never fades.
After the final clear, each finished gold bar is returned to the warm space to air dry overnight (with the heater turned off). Wait at least 24 hours before handling your parts. After allowing a few days to let the Spectra Chrome finish fully cure, the completed gold bars are ready for delivery.