Painted outdoor lamps get severely aged from weather exposure. Using a sand blaster and powder coating system, you can easily restore the lamp to its pristine condition. This Instructable shows how we did it. We made it at TechShop and you can too (learn more at http://techshop.ws).
• Sand Blaster (we used a Skat Blast system)
• Powder Coater (we used an Eastwood Dual Voltage Powder Coating System)
• Industrial Oven (we used a unit made by Ted’s Fabrication)
• Sink with hot and cold running water
• Safety glasses
• Chemical-resistant gloves
• Small scrub brush or scuff pad
• Oven-safe glove
• Bare wire (we used 16 AWG copper)
• Cleaning agent (we used TSP)
• Powder Coat Paint (we used Cardinal Paint polyester TGIC powder, T241-BK59)
• (Optional) Spray lubricant (we used Tri-FlowTM)
Step 1: Disassemble the Lamp
Before you begin the project, make sure to familiarize yourself with the basic operation of your equipment and the general safety precautions recommended by the equipment manufacturer.
In order to fully restore the lamp to a pristine state, it must be completely disassembled so that each piece of the lamp can be handled separately and all surfaces are fully exposed. Our lamp was held together with threaded knobs and threaded rods. If your lamp has been weather-aged for a number of years (ours had over 20 years of unprotected outdoor exposure), threaded connections will likely be very hard to loosen due to a build-up of corrosion in the threads. If any threaded connector (ie, screw, nut, rod, etc) cannot be readily removed, spray the connector liberally with a penetrating lubricant and let it sit overnight.
Step 2: Sand Blast the Parts
Like any paint job, the key to a professional-looking result is thorough surface preparation. A sand blaster is a quick and easy way to strip metal parts back down to bare metal. We used aluminum oxide for the sanding media which gave a very nice finely-textured finish while still achieving relatively fast stripping. It took about 2 hours to fully strip the parts.
Step 3: Pre-painting Wash and Bake
Once the parts are blasted down to bare metal, they need to be washed to remove any traces of blast media, finger oils and other contaminants that could prevent the powder paint from adhering. Steel parts can be cleaned with an alkaline cleaner like Tri Sodium Phosphate (TSP). Bare cold-rolled steel will rust quickly when exposed to water, so only work with one part at a time.
• Scrub all surfaces and corners of the part with the cleaning solution using a brush or scuff pad and remember that surface preparation is key, so err on the side of over-scrubbing.
• After scrubbing, rinse the part thoroughly in clean water to remove any traces of the cleaning solution.
• Manually shake off any water pooled along inside edges, then transfer the part onto a clean metal wire fashioned with small fish-hook loops on both ends. Make the wire long enough so you can grasp the wire without any risk of bumping the part with an oven-safe glove.
• Immediately transfer the cleaned part to an oven that has been pre-heated to 375 degrees Fahrenheit and bake for 10-15 minutes to drive off any trapped moisture, oils or other gasses.
Step 4: Powder Coat the Parts
Once the parts have been transferred from the pre-bake oven to the powder coating booth, do one last visual inspection to make sure the parts are truly clean. If you see any sign of contamination, go back and repeat the scrub/pre-bake step –powder will not stick to a contaminated surface.
Step 5: Bake the Parts to Cure the Powder Coat
After all the parts have been powder coated, transfer them to the oven for final cure. Our low-gloss textured black paint specified a 10-minute bake at 340 degrees Fahrenheit.
Step 6: Reassemble the Lamp
Reassemble the lamp and revel in the success of your renovation project!