I used to use a commercial blade cleaning product with the no-nonsense name of “Saw Cleaner” to remove pitch from my circular saw blades. It did a great job — you just sprayed it on, let it sit for a few minutes and then wiped off with an old tooth brush and warm soapy water, followed by a final rinse. The blade always came out spanking clean. In spite of this product’s proven effectiveness, I eventually decided to explore a more user and environmentally friendly alternative. Perhaps it was the warning on the Material Safety Data Sheet (MSDS):
Inhalation is the primary source of exposure and may cause severe respiratory irritation, nausea, dizziness, fatigue, confusion, unconsciousness. Severe skin contact may cause irritations and burns. Possible skin absorption. Eye contact may cause severe or permanent damage.
Pretty scary, eh? It turns out that the active ingredient in this product is sodium hydroxide (NaOH), also known as lye, caustic soda, or just caustic. And it is indeed caustic as so succinctly put in the MSDS. Sodium hydroxide is also the main ingredient in many spray-on oven cleaning products. If you’ve ever used them, you know how brutal the fumes can be. And there are other nasty chemicals in some oven cleaning products. Like ethanolamine, a solvent that can cause coughing, headache, shortness of breath, sore throat, and asthmatic reactions. Or ethylene glycol, which has been implicated in causing birth defects with long-term exposure.
In addition to the toxic effects on our bodies, oven cleaner and saw blade cleaning products with caustic ingredients can potentially damage saw blades. The folks at Freud recommend against such products because they attack the binder in the carbide and the brazing used to secure the teeth to the blade. Personally, I have never observed such blade damage but I never leave cleaning compounds in contact with the teeth for more than a few minutes. (Freud ran a test where a saw blade sat in a caustic solution for 24 hours). Still, the possibility of tooth failure from caustic ingredients is a cause for concern.
What Other Woodworkers are Using to Clean Saw Blades
In researching an alternative to caustic cleaning agents, I came across a slew of ideas from various woodworkers on the Internet. Here is a sampling:
Acetone – Does a good job removing pitch (and paint). Potential fume issues and not clear what effect a long soaking would have on non-stick coatings.
Baking soda – Mix with water and let the blade soak for awhile (one person leaves his blades in solution for 8 hours). Cheap and non-toxic.
Coffee – Soak blade overnight in a strong coffee solution and the pitch will be gone by the morning. Interesting…
CMT Blade and Bit Cleaner – Safe for the hands, non-toxic, and reportedly works.
Dawn soap – Soak blade in a soapy solution using Dawn (or other dishwashing product) and then brush off with an old toothbrush. Works best on fresh pitch.
Denatured alcohol (DNA) – Reportedly dissolves resin in about 5 minutes to where it easily wipes off with a rag or using a soft bristle parts brush for the worst spots. Doesn’t damage the factory coating or paint on the blade.
Electric fry pan – Insert blade, cover with water, turn on heat and let soak for “awhile”. Follow with a quick scrub using a brass brush. I am not making this up.
Formula 409 – Several people indicated that it works well plus there are no fumes or mess. At least one woodworker follows up with a spray coating of Boeshield t-9.
Greased Lightning – The name says it all. One person says it’s the best and cheapest thing he has ever used (he mixes 1 part cleaner to 1 part water in a spray container).
Kerosene – Soak overnight in a vented container and brush or wipe clean the next day. Recommended by at least one blade manufacturer.
LA’s Awesome – Get it on the cheap at the Dollar Store. Spray on, let steep for a few minutes, and then brush off.
Paint thinner – Works well at removing pitch but produces flammable fumes and will remove painted stenciling on the blade.
Trisodium Phosphate (TSP) – Mix with water and let soak for an hour or two. Cheap and works well. Typically used as a toilet bowl cleaner.
WD-40 – Commonly used as a post-cleaning spray to prevent rusting but some also use it to help dissolve pitch.
Simple Green – A popular and effective cleaning agent that is reportedly non-toxic, biodegradable and all that good stuff. Typically involves a 5 to 15 minute soaking followed by a light brushing and a water rinse.
Sudsy ammonia – Soak it for a few minutes in an old pizza pan and presto. It is a bit harder on the nose than the Simple Green, but it works well.
More on Simple Green
It seems that many woodworkers are using Simple Green and are pleased with the results. A typical post: I applied some Simple Green using an old toothbrush with the blade in an old pizza pan, then rinsed off with water. Coated the blade with WD-40 and wiped clean… Worked well. It’s not entirely clear why Simple Green has become so popular but some likely reasons are that it’s been around for 30+ years, is relatively inexpensive, has no caustic ingredients, and it gets the job done. However, a word of caution is in order here. Do not leave blades immersed in Simple Green for extended periods of time because the active chemicals in it will damage the carbide. Here is what Carol Chapin from Simple Green has to say on the matter:
“Simple Green has been successfully used by many woodworkers over many years as a good spray-wipe-and rinse cleaner for saw blades. When pitch is fairly fresh (within a 12 hour period of deposit,) it is fairly easily removed by Simple Green. Older, dried out pitch is much more difficult to remove. What we do not recommend is long-term soaking of cobalt/carbide blades in Simple Green. Long exposure like this can possibly cause cobalt leaching that will, in turn, effect the integrity of the carbide. Shorter term “spray/wipe/rinse” applications do not pose that kind of problem. We would recommend dwell times of full-strength Simple Green upon cobalt/carbide steel to be no more than about 15 minutes.
As mentioned in my earlier email, if you have a blade that has an older, tougher buildup of pitch, try soaking the blade in strong coffee overnight. Several folks have told us that this does work.”
Sounds like good advice to me… (but I wonder what brand of coffee works best?)
What the Blade Manufacturers Recommend
I came across a quote from one Charles McCracken of Freud Inc in regards to cleaning saw blades:
“Definitely avoid oven cleaner and other caustics. They attack the cobalt binder in the carbide and can lead to carbide failure (translates to tiny missiles of carbide at 100+ mph). Also, Freud and some other brands of blades have a tri-metal brazing foil that uses copper alloy for a cushioning layer. The copper can also be affected by these cleaners (translates to larger missiles of carbide). We recommend soaking overnight in kerosene in a vented container and using a stiff nylon bristle brush to clean. Teflon coated plates will clean up with a soapy cloth (except for the teeth as mentioned earlier). There are commercial blade cleaning products that are not caustic but we don’t officially sanction them. I’ve personally used Simple Green concentrate with good results.”
Forrest also suggests soaking blades in kerosene to remove “gooey pitch” followed by a light spray of WD-40 to prevent rust.
I came across some interesting material about cleaning saw blades at the website of Carbide Processors Inc., a company that provides a variety of saw blade services including brazing of carbide teeth. An article titled Can Cleaners Hurt Saw Blades indicates that their research has not shown that caustic solutions damage Freud saw blades or blades with other grades of carbide. The author concedes that “there may be a bit of an effect but too small to be of practical concern. ”
Another page on the Carbide Processors site contains feedback from a number of professional saw shops in terms of what they use to clean saw blades prior to sharpening or brazing operations. Of interest here is that many of these shops are using a sodium hydroxide / water solution in a soak tank. Some heat the solution to speed up the pitch softening process. Most of the respondents do not list soak times although one does say that after a 5 minute soak in the heated tank, gummed saw blades are easily cleaned.
This same page includes results from saw blade cleaning tests conducted in house by Carbide Processors. These tests indicated that a cheap sodium hydroxide based oven and grill cleaner from a janitorial supply store was far and away the best cleaner followed by Easy Off oven cleaner, then two citrus based cleaners (Orange Fresh, Orange Clean). Simple Green and 409 were not as effective and Brakleen was the worst at cleaning.
It would seem that it’s hard to beat a caustic cleaning solution when it comes to cleaning pitch from saw blades in as short a time as possible. If you run a commercial saw blade repair/sharpening business where time is money, one can certainly grasp the business rationale for using a caustic solution. If you don’t run such a business and only need to clean saw blades on an infrequent basis, I think a sound argument can be made for not using, or at least limiting the use of, caustic solutions given the safety issues associated with them.
What I Now Use to Clean Saw Blades
This is a work in progress… I have backed off from exclusively using a sodium hydroxide based product for cleaning saw blades and now mostly use Simple Green or 409 or other spray on products of that ilk. These products all seem to work well when the pitch is fresh — it’s usually a matter of spraying on, letting soak for about 5 minutes and then brushing off with an old toothbrush and warm water. Followed by a final rinsing and drying of course.
For older, more stubborn pitch, I will occasionally reach for that can of saw cleaner with the powerful, but nasty, caustic ingredients. In spite of the fumes, it is convenient to use and works fast. Real fast. However, I’m weaning myself from the stuff and experimenting with other cleaning agents, including kerosene and denatured alcohol. Possibly even baking soda or Pinesol. I hope to report on the outcome of these experiments in a future article.