This post was prompted by a newbie posting a question about fix a leak in a compression fitting he'd installed. He installed the compression fitting cuz he didn't know how to solder. And, he'd tightened that compression fitting so much he was scared that further tightening was gonna do more harm than good, but the leak wouldn't stop. So, he couldn't go forward or backward. I'm just gonna explain the basics of what you do here because what to do is the easiest part of it. It's the WHY you're doing it that I'm probably gonna spend more time on because that's something that not everyone knows. And if anyone has any questions, please post cuz others probably have the same questions. Also, would the experienced plumbers in here PLEASE put in their ideas too. EVERY newbie eventually learns to solder, and in my view, the sooner the better so they don't have so many compression fittings to replace once they start soldering. 1. The Torch: You wanna buy a propane torch that mixes the propane with air in a short tube before burning it. That much is a "must", and all the other bells and whistles like a piezoelectric lighter built into the torch is OK to have, but it's really not a necessity like mixing the fuel and air before igniting it. The famous "bunsen burner" in your high school chemistry classes used this basic principle of mixing the fuel and air before hand to generate much higher temperatures than you can achieve with a "pencil tip" torch (so named because it doesn't mix the air and the fuel before ignition, and the resulting bright blue flame inside a faint blue flame looks like the sharpened tip of a pencil). You want the flame on your torch NOT to have that pencil tip shape inside the flame. Also, try to get a torch with a curved nozzle so that when pipes are close to a wall (or whatever) you can sneak the torch tip behind the joint you're soldering. That way, by heating the back of the fitting with the flame pointed toward you, and applying the solder to the side of the fitting in front of you, you know that when the solder starts to melt at the front of the fitting, the rest of the fitting that's closer to the flame (which is all of it) is hotter and you'll fill the whole joint with solder. There won't be any cold spots where the molten solder doesn't flow into. Also by appling the flame behind the joint and the solder in front, you can more easily see when the solder starts to melt and better anticipate when the joint is going to start taking solder. So, having a curved tip on your soldering torch is an advantage to getting the torch in the best possible location for successful soldering. I should mention MAAP gas, I guess. I think every torch that burns propane can also be mounted on a MAAP gas cannister. MAAP gas stands for methyl-acetylene - propadiene, meaning that MAAP gas is a mixture of two gasses; methyl-acetylene and propadiene. Acetylene is easy to understand: It's HC|||CH where ||| is meant to represent a TRIPLE carbon-carbon bond. (I just can't make any such thing on my keyboard.) If you replace one of those hydrogens on the end with a methyl group, you have methyl-acetylene, or: HC|||C-CH3 Propadiene is similar to methyl-acetylene. If you move one of those bonds in the triple bond over to the other side, and balance everything properly, you get propadiene: H2C=C=CH2 (so, both gasses in MAAP gas have the chemical formula of C3H4, and if truth be known, it would make more sense to call the stuff C3H4 than to call it methyl-acetly-what-ever or MAAP for short.) It's the breaking of those double and triple carbon-carbon bonds where the lion's share of the heat comes from, so both C3H4 gasses burn hotter than ordinary propane (which is H3C-HCH-CH3). If you burn pure acetylene in pure oxygen (so that you don't waste heat warming up all the nitrogen in the air), you get a flame hot enough to easily melt steel. So, even though you can use MAAP gas in your propane torch, and many if not most plumbers do do that so they can work faster, I'd discourage it because the fluxes you're using might not tolerate the higher temperatures, and that could lead to some bad solder joints. Put MAAP gas on the back burner until you get proficient at soldering. I'm gonna post this for the time being cuz my computer's been crashing lately and I don't want to retype it all. Next post: what you do.