Brazing: Removing Oil and Grease
Brazing: Cleaning Off Oil and Grease
I had two separate calls today. Both of them involved brazing problems in which cleanliness was an issue. In both cases they were using a solvent as a degreaser.
The tool industry is full of people who work with machinery as though they were born with a wrench in there hand so I’m going to try and construct an analogy explaining grease removal in terms of tools.
Suppose you’re working on a machine and you ask me to hand you a wrench. If you have a set of 7 or 9 or 11 wrenches than the chances of me handing you the correct wrench just on the information given is maybe 1 in 7, 1 in 9 or 1 in 11.
There are different kinds of oils and greases. There are lots of ways to classify them but they are generally put into something like five or seven different classes.
So the oil and grease you want to clean off is like the nut you want to turn. Selecting a solvent to do the cleaning is like selecting the right wrench.
Using a strong caustic solution, such as Easy Off oven cleaner, is like using a crescent wrench or a pair of vise grips to turn the nut. It is not the ideal tool but it is sure to get the job done no matter what size nut you have.
Solvents do not remove oil and grease. Solvents just dilute it. If you put a shot of whiskey in a glass, you can add as much water as you want to and dilute the whiskey but there will still be whiskey. Only the concentration will change.
If you put a little oil in the bottom of the bowl and add water to it, then the oil will float on top of the water. Bowls typically get wider as they get taller, so the more water you added the farther out the oil will spread and the thinner the layer will be.
Caustic solutions saponify oils and greases. Saponify means they actually break down the oils and greases into soap or soap like components. Two things are important here. The oils and greases are actually destroyed. The oils and greases are broken down into components that are easy to rinse off with plain water.
Now that we have covered all that, I do have to admit that every day throughout industry people successfully clean with solvents. The above is important because a cleaning problem from a process using solvents may be solved by switching to a caustic-based solution. I mentioned easy off oven cleaner because it is easy to use, readily available, everybody is aware that it could be dangerous and has special rinsing agents that make it easy to remove. We did a test on different cleaners for saw blades and the most economical and most effective was a gallon jug of barbecue grill cleaner from a local janitorial supply. You can also use straight lye but straight lye is typically straight sodium hydroxide were straight caustic soda. A commercially prepared cleaner will typically have additives to make it more effective and other additives to make it easier to remove by rinsing.
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