[jshorva65]

MIKE: The Aquadag can be recoated using G-C Electronics part# 10-4807 conductive paint. It comes in a 12-ounce spray can available for about $27 through ACK Radio in Georgia and marketed as an EMI/RFI shielding product. Before recoating, you'll need to remove the tube from the cabinet, remove the yoke from it, clean the tube surfaces with denatured alcohol, and mask it. Discharge the dag capacitance before handling the tube. Use great care to not drop, strike or scratch the tube during any part of the handling of it. The glass construction and high vacuum make for a spectacular and dangerous implosion if the glass envelope breaks since the tube surfaces are actually supporting tremendous atmospheric pressure. The faceplate alone is under more than two tons of pressure from the atmosphere. Set up a "paint booth" in a garage by obtaining an old large-appliance box and cutting it to leave the bottom and three full sides which will define an area where you can leave the tube unattended overnight to dry without it being damaged. The booth will also stop any overspray from getting on floors, walls, etc. Mask the faceplate of the tube with a sheet of plastic and tape the plastic to the tube with a continuous strip of tape that lines up exactly with the edge of the original dag border around the funnel-to-faceplate seal. Set the tube face-down on a thick, soft surface like an old blanket folded into about a 30" x 22" rectangle. Next, wrap plastic around the tube neck all the way up and secure the wrap with electrical tape. Run tape around where the original dag ends to mask exactly along the original border adjacent to the neck. You'll also see a big, circular void in the dag coating at least 4" in diameter (usually close to 6" on those 24" tubes) around the anode connector. Thoroughly clean the glass (again) around the anode connector with denatured alcohol to remove all the carbon trails. Inspect this area with a magnifier if necessary. This will be the most critical region of the tube surface since it's directly adjacent to the anode connector and about 15kV. Mask this circular area with electrical tape, again taking care to follow the original factory border. The clearances are critical and usually specified in the original design drawings of the tube with a tolerance (+/-1/8" to +/-1/4" typically). Verify an ambient temperature between 60-80 degrees Fahrenheit as that's the optimum range for application of the paint. Shake the dag spray for at least a full minute to make sure it's thoroughly mixed. Spray from a distance of 8" to 12" from the glass and keep the spray moving to form a nice, uniform, thin coat. Turn the tube around by rotating the blanket it's resting on if you're having trouble getting to the opposite side of the tube. Once you've got a nice, even first coat, let that dry for 1/2 hour to 1 hour. Spray another thin, uniform coat and let dry. Use a third coat if desired. Turn the "booth" around with the open side against a wall and mark the box "CAUTION, KEEP AWAY", "WET PAINT", etc. Let dry overnight. Again, handle the tube with great care. The structure is very strong to support all that pressure, but tripping over a crack in a driveway while carrying it and dropping the tube will almost certainly shatter it. In my "young and crazy" years, we took "dud" picture tubes into a large, open field on the few extra acres of land my grandparents owned behind the family business where we did our target practice and shot these 12" to 24" tubes with high-powered rifles and shotguns from about 50 yards away. The noise was about equivalent to 1/4 to 1/2 stick of dynamite. It wasn't unusual for the implosion of a 21" tube to hurl palm-sized chunks of glass 20-30 yards from "ground zero" and displace loose dirt leaving a "crater" under the spot where the tube was sitting. Afterward, we vacuumed the area with a miniature version of a street sweeper that was normally used to sweep 6 large driveways and a parking lot on the front few acres. Basically, it was a cross between a lawn tractor and a vacuum cleaner. As I remember, there was quite a mess to be cleaned up after an afternoon of tube-shooting. I've never seen a tube "blow" in a repair shop, but I heard about an incident when a not-too-sharp tech made the mistake of cutting the tension band off of a 25" tube to remove its mounting lugs. Apparently, he heard the glass start to crack just in time to get safely out of the room before it "blew" and found chunks of glass embedded in the walls after the blast. From the oldtimers' telling of that story, it seemed amazing that no one was seriously hurt or killed.

I just re-dagged a 10BP4 for a customer who bought it from an eBay seller who had wrapped it in adhesive-backed bubble wrap which was placed with adhesive directly against the dag. I recommend wrapping CRT's for shipment using an inner layer of non-adhesive bubble wrap and then it's ok to use the adhesive-backed stuff as outer wrap so it won't touch the dag.

JSTOUT: I'm also 38. My son, age 14, will be recapping his first tube radio soon. Tim has been playing guitar for a few years and has a strong preference for tube tone. He's been helping in the shop, mostly on lift-and-carry tasks that require two people like unboxing 630TS cabinet/chassis assemblies to get them ready for "pulling" the chassis for recapping.

I've been "technically curious" since childhood. I've traced everything back to the explosion of the plug of a defective box fan in my hand at age three. Tim's experience is similar, having turned on a large guitar amp while using it to support himself as he was learning to walk and then run screaming out of the room when bumping it caused the reverb springs to bang together and the amp to emit a loud bang and ear-splitting howl. To this day, he remembers that incident.