# The effect of Sodium Hydroxide on Tungsten Carbide



## Dal300 (Aug 4, 2011)

Big Words.

I keep seeing posts to the effect that Sodium Hydroxide (Lye or Oven Cleaner) will degrade Tungsten Carbide cutters. Usually on saw blades, but we could extend this to anything made with tungsten carbide. This would include most of the carbide tipped band saw blades, drills or moulding and router cutter heads.

My question is this:

Is there any definitive scientific proof that Lye or Oven cleaner, (which isn't all that strong a concentration of Lye), actually hurts the carbide tips of a saw blade or other tool containing carbide or is this just a tale that is told because someone told you it was true.

We aren't speaking of anecdotal or empirical proof here, just hard cold scientific facts.

From what I've read in a few minutes of Googling around the internet, unless there is a caustic soda (Lye) concentration of over 40%, it can't actually penetrate the tungsten carbide enough to cause any real measurable harm. I'm not saying that I did any real in-depth research, just a quick half hour of looking at different scientific treatises on the effects.


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## knotscott (Feb 27, 2009)

Dunno about data on the effect of caustic on the carbide, but I simply found oven cleaner took the lettering off one of my blades and was messier to use than degreaser sprays like 409. I stopped using oven cleaner because other methods were more convenient and as effective.


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## BillWhite (Jul 23, 2007)

Ya ain't gonna see me using oven cleaner in my shop. My blades and bits cost too much to be used in a science project.
No scientific proof to be had here, but I've been doin' it my way for years without any degradation of carbide.
Bill


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## Dal300 (Aug 4, 2011)

Bill, following that logic shouldn't we still be using asbestos to insulate heating systems and wood stoves?


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## Danpaddles (Jan 26, 2012)

Ummmm….. Dallas- about that asbestos thing…......

I think part of the argument about using Easy Off is that is might degrade the braze that holds the teeth on, not so much that it eats the carbide.

I use it, yes, it will attack some lettering. But it takes the resin off the teeth quickly and easily. Yes, it is messy, I just lean the blade on the inside of the laundry sink and spray away, flip and spray some more. Wait 5 minutes, then brush with an old tooth brush (or, I guess a tooth brush belonging to someone you do not like.). Rinse well, since I have heard of this corrosion thing, I rinse very well, and then inspect closely.

I know I get much nicer cuts for 5 minutes work. Saw cuts faster, and their are no saw marks to be seen, right after a good cleaning. So- don't stop cleaning your blade!

You know, sometimes teeth come off blades for reasons other than having to do with the cleaner used.


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## MrRon (Jul 9, 2009)

I haven't had any problems using TSP. Ijust soak the blade for up to an hour, brush and rinse clean.


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## Viktor (Jan 15, 2009)

I doubt that lye (NaOH) would affect tungsten carbide cutters subject to occasional cleaning.

There are two things to consider - corrosion of tungsten carbide (WC) itself and corrosion of the binder (usually Co, Ni, or other alloys). 
The solution pH determines the process. In neutral and acidic environment the corrosion process of WC-Co consists mainly of Co dissolution. In alkaline conditions dissolution of WC becomes more significant:
- Hochstrasser-Kurz S.; Mueller Y.; Latkoczy C.; et al. 2007. Analytical characterization of the corrosion mechanisms of WC-Co by electrochemical methods and inductively coupled plasma mass spectroscopy. CORROSION SCIENCE 49(4): 2002-2020.

Having said that in practical terms WC-Co and especially WC-Ni cutters should have good resistance to bases and less resistance to acids. Many manufacturers corroborate this too. In fact, some studies suggest that micro-abrasion under alkaline conditions resulted in lowered wear rates possibly due to formation of protective film:
- Thakare M. R.; Wharton J. A.; Wood R. J. K.; et al. 2007. Exposure effects of alkaline drilling fluid on the microscale abrasion-corrosion of WC-based hardmetals. WEAR 263: 125-136 
- Thakare M. R.; Wharton J. A.; Wood R. J. K.; et al. 2008. Exposure effects of strong alkaline conditions on the microscale abrasion-corrosion of D-gun sprayed WC-10Co-4Cr coating. TRIBOLOGY INTERNATIONAL 41(7): 629-639

In either case it seems pretty safe to wash the blade in alkaline cleaner for few minutes followed by rinsing. However, oven cleaner may contain other chemicals that could cause harmful effect.

PS. By binder I mean the matrix which holds together WC grains (not the braze). Cutting tips are not solid WC.


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## knotscott (Feb 27, 2009)

Dallas - My question is what advantage does oven cleaner has over other proven methods that have fewer potential downsides?


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## pons (Jan 24, 2012)

Even a dilute sodium hydroxide concentration will have an effect on the carbide over time, but with minimal exposure and thorough rinsing and drying, you shouldn't see any problems. 
If you are looking for a degreaser, a tablespoon of trisodium phosphate(TSP) in a gallon of water will work. That is the stuff the epa took out of laundry detergents a while bacl.

pons


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## Dal300 (Aug 4, 2011)

So far only one response that isn't anecdotal.


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## crank49 (Apr 7, 2010)

Look up stress corrosion cracking.
Also related, hydrogen embrittlement.

Sodium Hydroxide is a caustic which can cause stress corrosion cracking, even in mild steel, but specifically in austennitic steels, such as common 18-8 stainless. which can lead to sudden catastrophic failure.
It is the propagation of fractures along the grain boundries of the nickel and chrome and iron molecules where subjected to cyclic loading.
The nickel silver brazing material used to attach the carbide teeth would be easily attacked.


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## JJohnston (May 22, 2009)

I don't see your point here. If you want to clean your blades with oven cleaner, clean your blades with oven cleaner.

Does anybody know why I shouldn't start popping the clutch on my truck? Honestly - have you ever seen a transmission fall out because somebody popped his clutch?


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## Dal300 (Aug 4, 2011)

Whoa, JJohnston, don't get your panties in a wad. I didn't say that I was going to clean a blade with oven cleaner, I merely asked if there was any scientific evidence to prove the allegations that oven cleaner would harm a saw blade.


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## JJohnston (May 22, 2009)

But you must have wanted to know for a reason, right?


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## Dal300 (Aug 4, 2011)

Yep, I always like to know stuff.
The point of this question is that I keep reading that using oven cleaner will ruin the carbide teeth of a saw blade but I haven't seen any evidence to back it up.

I'm just looking for the evidence.

As for the transmission flalling out from popping the clutch I have to answer truthfully, that no I haven't seen that happen but I have seen transmissions come apart in itty bitty pieces spread all over Sunrise mountain near Las Vegas because a truck with a full load of sheet rock popped the clutch. (Actually, his foot slipped off the clutch).


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## Viktor (Jan 15, 2009)

I just reread my first post and I think I obscured the issue quite nicely there.

While WC, being a composite, is a good candidate for corrosion cracking I would be cautious to make broad generalizations as what could cause it in this particular material. Corrosion cracking is notoriously substance specific. It is chlorides for austenitic steel, NaOH for mild steel and so on. In WC-Co hydrogen fluoride (HF) has this effect and I would imagine other halide ions (chloride) might do the same, albeit less potently.

Experimental studies consistently show that the binder (Co, Ni, etc.) leaching is by far the primary corrosion concern for WC. The leaching rate increases as pH decreases (acidic environment). This is in agreement with HF induced corrosion cracking mentioned above. Of course there is more to NaOH solution than high pH, but I can't think of what else could go on there Na+ related to corrode the substrate.









Perhaps advise not to use oven cleaner (lye) on blades stems from overall caution to avoid household cleaners, many of which do contain chlorine. It is plausible that oven cleaner contains other active corrosive substances, but the original question was specific.

Keep in mind that we are talking about occasional cleaning, not prolonged exposure such as in boiler filled with chlorinated water.

All this was just my humble opinion, but thank you for this interesting and thought provoking question.


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## Dal300 (Aug 4, 2011)

Thanks Viktor, that is interesting.
So, should I infer that Oven cleaner with it's amount of lye moving the Ph upward, there is less chance of corrosion of the carbide itself, but possibly more chance of corrosion of the brazing material?

Years ago I had a friend who had a small machine shop and as a sideline rebuilt cutter heads and blades for a large sawmill nearby. 
The carbide teeth he made himself for each of the different blades the mill used. I remember him brazing the teeth into the round blades and the monster 6" band saw blades with what looked to me like regular old brazing rod. 
Now I look at my blades and that braze I'm sure isn't bronze rod. Is there any correlation or reason behind the change?


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## Viktor (Jan 15, 2009)

My guess would be yes. But don't hold me to it 

Not sure about brazing. I think copper-based alloys are still widely used. Sometimes brazing consists of layers as a sandwich to reduce stress and bronze is simply masked… I'm just brainstorming. Don't know much about that.


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## Bertha (Jan 10, 2011)

This is an interesting debate and I thank you Viktor for the science. If carbide stock wasn't so darn expensive, this would be a pretty simple experiment I do all kinds of awful stuff with chemicals that I shouldn't. I've used oven cleaner on tools before but I'm a TSP freak. I used to work in the brewing industry and we'd use TSP to clean just about everything. OK, I'm rambling off topic now. Carry on!


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## Dal300 (Aug 4, 2011)

Al, 
I once worked for a restaurant supply dealer that would buy and sell used equipment on the side. We would go into a defunct restaurant and clean out all the old stoves, grills, deep fryers, mixers and everything else, take them to the warehouse and spray them down with lye water, let it sit for 15 minutes and clean it off with a steam cleaner. It's amazing how clean it came out!
I never saw any evidence of cracking or corrosion at any of the joints whether it was brazed or silver soldered or TIG welded.


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## crank49 (Apr 7, 2010)

My understanding is the carbide teeth are attached with silver solder. Not solder like lead or tin used for wiring but a silver phosphorus copper alloy. I use this material to repair frames on glasses and working with stainless jewelry, like watch bands. The stuff I use is 55% silver and it loves stainless.


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## BillWhite (Jul 23, 2007)

Yep! No asbestos (cough, cough), and I'll use the Simple Green or A & H Washing soda for my blades. Oh well….I just posted my opinion. Pay me for what it cost ya.
Bill


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## Dal300 (Aug 4, 2011)

Hey Bill… I also use A&H washing soda, not only for cleaning blades but the wife uses it for washing too! I also use it for electrolytic de-rusting of tools and parts.


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## gdpifer (Jan 23, 2011)

I ran a sharpening shop for over 10 years and knew quite a number of other sharpeners. I would say that 99% of us used lye mixed in water in a soak tank to clean saw blades. Over the years I cleaned literally thousands of blades, many of the blades over and over again. Blades would wear out from use over the years but I was unaware of any problems develpeing from the lye. Possibly if the concentration was extremely high there might be a problem but the diluted mix I used would not seem to have been a problem. I do know that there probably wasn't a more effective product around to clean pitch and resin off of a blade. I used the same mix to clean lawn mower blades. After soaking the blades were cleaned throughly with hot water to keep the lye from continuing to work. Just my 2 cents worth.


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## Danpaddles (Jan 26, 2012)

If we look at Viktors graph, and wade thru his discussion, we will learn that ….... our days of college chemistry were almost completely wasted when said knowledge is quantified over time.

Similar to the discussion of corrosion, which also needs to have the element of TIME inserted into our (armchair chemists) harassment of the perfect blade cleaner.

Since my wife bought this can of Easy Off before we bought the self cleaning oven, and in as much as it is just sitting around anyway, I will continue to use it, remembering to rinse well within the hour of application. That should keep me pretty well off the curve pictured above, where results were measured in 1/10 mm/year. And we can't let that can of Easyoff go to waste, now can we.

I recently ran into a somewhat similar discussion of corrosion, where pH is maybe not the culprit. Reverse osmosis water should not be used with an Insinkerator hot water dispenser. The heater tanks will not last very long. Something about properties of ionized water. (I talked her out of making me stick my head under the sink for 3 hours last Saturday to install said Insinkerator, so the argument was worthwhile!)


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## Grandpa (Jan 28, 2011)

I love the argument Dan. 
I think *IF* there were cracking it would be in the weld area. I don't believe you will see that until the carbide hit you in the head *IF* it did indeed crack. I have some blades that appear to have brass on them and others that look like silver solder was used. that process is often referred to as silver brazing so…..it can still be brazed I suppose. I plan to run this past a welding engineer that I know and see what he thinks. Not that present company is lacking between the ears but this man is way smart. He is almost to the point of not being useful. The human IQ seems to go in a circle. You can be smart and way up the curve but when you go over too far you are of little use to other people…..well he is as high as he should go. Has a problem keeping friends. later


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## MrRon (Jul 9, 2009)

Gdpifer; I too ran a saw shop. I used to also use lye [sodiun hydroxide] to clean blades. Some of the blades that came through were so burned that it would take the power of lye to get them clean enough to shatpen. I don't think a short soak in lye will harm the carbide or the binder, but a long soak, like overnight, might have some effect.


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