TOPCOATING PRACTICE TILES
In the previous section, we applied an initial protective “glossy/frosty” topcoat layer to seal in the raw silver. We will now proceed with applying topcoat colors; as well as the final topcoat layer over the glossy/frosty tiles. Adding colors provides a custom look, and the final topcoat will restore the perfect mirror shine.
Before spraying the topcoat, ensure that your spray gun has been adjusted to the settings specified in the Topcoat Gun Settings section.
When spraying Spectra Chrome products, ensure that your work space is well ventilated; and always wear appropriate safety gear.
For this demonstration we will be using two different tint colors — yellow and blue.
Pour a few ounces of your mixed Topcoat 311 (no color) into two separate mixing cups; and add your desired color tints. We recommend starting with a ratio of (4) drops per ounce of Topcoat 311. As explained in the Tinting the Topcoat section, adding more drops of tints makes the formula stronger, and will produce a deeper topcoat color in fewer coats.
Stir the tints with a craft stick until the mixture is uniform in color.
Remember that your parts will always require one last layer of Topcoat 311 (no color) as a final protective coating. Be sure to set aside a few ounces of Topcoat 311 (no color) in a separate DPC cup, and reserve it for use as your final clear coat after your color coats are complete.
Topcoat 311 (blue color) is sprayed over the practice tile that has the “blue hue” caused by an over deposit of silver. We chose this specific tile to demonstrate the forgiving nature of the Spectra Chrome finish — if your silver did not deposit perfectly, a darker-colored topcoat can often hide and conceal the imperfections.
The topcoat application technique is very similar to basecoating:
- Hold the tip of the spray gun nozzle approximately 4 to 6 inches away from the part at all times.
- Position each pass of the gun so that 50% of the spray pattern overlaps on top of the previous pass.
- Ensure the speed and distance of the spray gun is always held constant with respect to the part.
With practice, you will develop an intuitive understanding of the ideal distance and speed to use when applying the topcoat.
Immediately after spraying, place the freshly topcoated tile into the warm space (with the heater turned off) to keep it protected while the topcoat solvents flash out. Allow 3-4 minutes of flash time before applying the final topcoat.
On the next tile, we will demonstrate applying a simple two-tone gradient. Begin by spraying Topcoat 311 (blue color) over the bottom half of the tile only.
The Spectrum UPS / Sagola DPC makes it quick and easy to swap between multiple colors of topcoat:
- Disconnect your spray gun from the air hose.
- Turn the gun upside down, and squeeze the trigger to allow residual paint to flow back into the attached DPC cup.
- Remove the attached DPC cup from the spray gun.
- Position the gun nozzle over an empty mixing cup, squeeze the trigger down, and pour lacquer thinner through the adapter on the top of the gun to flush out any remaining blue tint from the gun chamber.
- Keep pouring additional lacquer thinner through the gun until the stream exiting the nozzle runs clear.
- To change color, attach your DPC cup containing Topcoat 311 (yellow color) to the top of the gun.
- Reconnect your spray gun to the air hose.
- “Purge” the residual lacquer thinner from the spray gun by pointing it away from your workpiece and squeezing the trigger. Never spray directly at your part immediately after cleaning — any leftover lacquer thinner inside the gun chamber will negatively affect your topcoat layer.
Spray the other half of the tile with Topcoat 311 (yellow color). Notice how the overlapping areas between the blue and yellow tint produce the color green (blue + yellow = green).
On the third tile, we demonstrate what happens when the Topcoat 311 is applied too fast and too thick, with no flash time in between coats.
The bottom half of the tile is sprayed with several heavy layers of Topocat 311 immediately in quick succession. Notice how areas near the edges of the tile appear darker and raised due to excessive topcoat accumulation. This raised edge is called a “meniscus” — and it is an indication that your topcoat layer is too thick.
After a few minutes of flash time, a rash of “champagne bubbles” form in the topcoat layer. This is caused by excessive solvents in the Topcoat 311 reacting with the basecoat layer, creating gas bubbles. It is easily visible under a high-powered LED light.
To achieve deep topcoat colors, it is extremely important to gradually apply the Topcoat 311 in thin coats; allowing 3-4 minutes of “flash time” in between each coat.
To complete the finish, we will apply one last layer of Topcoat 311 (no color) as a final protective coating. Swap in your reserved Topcoat 311 (no color) by following the lacquer thinner spray gun cleaning procedure above.
Spray the Topcoat 311 (no color) using the same technique as used on the color layers. Make sure to spray the Topcoat 311 so that it wraps around the edges to the back of the part for complete coverage.
This final topcoat layer “wets out” any dry-spray areas, and brings out the glossy shine and maximum reflection. It also serves as an ultra-durable UV-protective layer for your finished workpiece.
Immediately after spraying, place your completed tile into the warm space (with the heater turned off) and allow to air dry for 24 hours. After thoroughly drying, the parts can be safely handled.
