Ideally, you have purchased a lamp that is in good condition and is ready to be fired up and taken underground. However, this isn't always the way the case. Many lamps are unsalvageable, but there are other lamps that are possible to restore. Often, the restoration is as simple as polishing the reflector a bit, replacing a tip, gasket, and felt, and the lamp is ready to be fired up. However, the lamp may need more serious work. This section will cover hardened lime, replacing the hook, structural damage done to the lamp, frozen bottoms, and leaky valves.
Calcite and corrosion
Many times after you have purchased a lamp you will find a large lump of hardened white lime at the base and sometimes covering the drip stem. If the lime has been sitting long enough, it will have converted into calcite. In some cases the calcite may even prevent the water from dripping. This is a fairly common problem, and it may even happen if you forget to clean out your lamp after a caving trip. The solution is also very simple. The lime needs only be submerged in vinegar. After several minutes of soaking and fizzing, you may want to try using a toothbrush to help persuade some of the lime off of your lamp. A bathroom cleaner "Lime Away" mixed with water may also help. You should mix the solution with 50% water and 50% Lime Away.
Replacing the hook
It may be that you will have to replace a hook because it is either damaged, or you may wish to attach a different style hook. First, you will need to purchase a new hook. Inner Mountain Outfitters carries blade type hooks. Once you have your new hook ready, you will need soldering iron designed for lead or silver solder. First heat the iron and loosen the solder around the old hook. You may also need to remove screws that may be holding the old hook into place. Make sure you cover any screw holes that may be left from the previous hook. Attach the new hook with a patch of lead or silver solder. Do not attempt to use solder intended for electrical wires. That solder is much too soft and will not hold properly.
When a lamp has been damaged it may not be repairable. However, many cavers have been known to remove dents from the inside of lamps. If lamp is dented, one may take a stick or other blunt object, insert it into the water door, and remove the dents from the inside out. If this is impossible, then one may drill a hole in the dented area, and make a small hook with which to pull out the dent. Once you have done this to the tank or bottom, or if they have been in any other way punctured or cracked, you can apply a lead or silver solder to patch the hole.
Occasionally there is significant corrosion on the outside of a lamp. Some cavers have successfully removed the corrosion with steel wool.
Should your lamp have damaged threads or a damaged gas tube, the lamp may not be salvageable.
Occasionally you will not be able to separate the top of the lamp from the bottom. The lamp will not even seem to budge. This happens because the lime from the spent carbide will absorb carbon dioxide from the atmosphere and turn into a crust of calcite. This is damaging to the brass and solder. If this has caused the lamp to become "frozen" then there are ways to separate the two halves.
The first approach will take some time and effort, though you probably already have the materials on hand. You will need to use a thumbtack, knife, or other acute object to perforate the gasket. Next strip the lamp of all visible parts (reflector, tip, wing nut, etc.) Then submerge the lamp up to (but not including) the gas pipe in Diet Coke. It is likely that any carbonated sugar free soft drink will do, however I have only used Diet Coke. It is important that you use a diet drink because sugar will corrode brass. I have tried this approach after being frustrated with a frozen bottom and then hearing a friend discuss how corrosive Coke was and what it would do to various objects. Figuring most drinks are made with carbonic acid (as well as other acids) I decided to give it a try. After two attempts at scraping away the gasket with a screwdriver, the bottom of the lamp was freed. You may want to experiment with other liquids using this method. Other acids such as vinegar and any other carbonated soft drink should work.
The second method is more of a brute force approach. Note that you may end up sacrificing the bottom of the lamp, but in most cases the top is reparable if not spared from harm completely. The procedure has a 50% success rate for recovery of both top and bottom, and almost always the top is salvageable.
First, strip the lamp of all removable parts. Then plug all possible holes, and cover them with tape. Next, thoroughly cover the entire lamp with a good coat of grease. DO NOT FORGET THE GREASE! You must then set the two ends of the lamp in separate beds of plaster. You can do this by using a plyethylene or prolylene freezer container, or cut milk containers. Make sure you carefully set the two ends of the lamp separately. Allow the plaster to set, and slip off the containers. Take one of the two blocks that you have formed, and grip it in a vice. Grab the other and twist. At this point you will have either freed the lamp from its frozen state, or you will have ripped the male threads off the bottom. You may carefully work these pieces of metal out of the top with a pair of pliers and a carefully placed knife. Once the work is done you may use a chisel and carefully break the plaster. Again, the procedure has about a 50% success rate, and some further damage may be done to the top. I.E., the hook may be broken. But, the top will be salvaged, and that is the more valuable part of the lamp.
Leaky water valve
If a lamp's water valve is leaky, then a rather simple procedure can be used. Turn the valve two thirds of the way to full open. Then use a torch flame, and direct it sideways against the valve post. At the same time press downwards on the valve ball until the solder begins to soften. Then remove the flame and wait for the solder to harden again.
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