The disposal fees of most solvents can be greater than their original purchase price. They can also add an additional 10 to 15% to the cost of your finishes. It would make sense that controlling your waste would help your bottom line.
Post catalyzed products like conversion varnishes normally can not be reused once the catalyst has been added and they reach the end of their pot life. Wasting a quart a day would result in about a 5-gallon pail a month or a 55-gallon drums worth in a year. At about $30 a gallon purchase cost and $350 a drum disposal fee, that 1 quart a day will cost you about $2000 a year.
Earlier we talked about how poor scheduling can boost your solvent consumption because of the increased number of cleanings required by additional change-overs. The type of spray system that you have will also affect the amount of solvent required to clean it out.
|Spray System Type||Clean-Up Solvent Required|
|1 Quart gravity feed cup gun||4 to 6 oz|
|1 Quart siphon feed cup gun||8 to 10 oz|
|Air Assisted Airless pump – 20’ hose||16 to 24 oz|
|Pressure pot – 20’ hose||64 oz or more|
The quantities listed are for clean-up after a clear finish.
Clean-up after paint could require 2 times the volume of solvent.
Solvent Recovery and Conservation
- Pour off solvents into smaller marked containers for dispensing. They are easier to control and less likely to spill. Squeeze bottles with a spout work well for flushing out quart cups.
- Re-use spent thinner for heavy cleanup chores, like washing out a pressure pot. After initial wash use new thinner for final cleaning.
- Invest in an automatic gun washer. The washers can be used to clean conventional and HVLP spray guns and cups.
- Some have attachments for cleaning material hoses. The solvents used in the cleaning process are recycled and re-used. The better washers have filters that remove the contaminants from the solvents so they don’t get diluted and lose their cleaning power.
- Washing guns by hand is labor intensive and can generate significant quantities of solvent wastes. Automatic gun washers reduce the amount of labor and the amount of solvent used for cleaning.
- When compared to manual gun cleaning, the solvent waste generated can be reduced by up to 80% because of the solvent recycling. Since automatic gun washers are sealed units, worker exposure to hazardous materials during solvent handling is also greatly reduced.
Food for Thought
Let’s say you spent 5 minutes and 10 ounces of thinner cleaning a spray gun and you cleaned a gun 9 times a week. Based on a shop labor rate of $60 per man hour, $8 per gallon of thinner, and $350 per drum disposal fee; you will spend almost $2400 per year on cleaning.
Every finishing operation generates waste. How you dispose of it can be a major issue, especially if you get an EPA audit. You will have to provide information as to how many gallons of finish you purchased, so they know that there is going to be a certain percentage of waste. The question is, “what did you do with it?”
If you are a very small user there is always the temptation to just dump your liquid waste in the trash. Don’t do it. It is this type of action that brought on the environmental regulations in the first place. Not only are you polluting, but the consequences, if you are caught, can be severe. The cost of proper disposal can often exceed the original purchase cost of the solvents involved, so it suits you well to tighten up your cleanup and other waste-generating factors in your finish room.
You are responsible for the chemicals that you purchase from “invoice-to-grave”, so the method by which you dispose of them could have an impact on your business years down the road. My understanding is that a special waste hauler that incinerates your waste is one of the safest options. You get a manifest that states that your material was destroyed, so you are no longer responsible for it. This is opposed to a company that will store your hazardous material. 20 years from now if they come across a drum at a toxic waste site and your name is on it, and then you are responsible for its disposal. It doesn’t matter that you had already paid someone to dispose of it and that they did not do it properly.
A Few Tips:
- Store your waste in a sealable 55 gallon drum
- Have a label on your drum that states that this hazardous waste
- List the date that that you started pouring off your waste into the drum
- List the date that you filled the drum
- Don’t keep too much waste sitting around. There is a maximum that is allowable to have on your site