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Guy Thomas

Getting back into thyngs and PAPRs

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Posted (edited)

So, I am determined to get back into making. I want to learn more about blacksmithing (tongs, hammers... and bottle openers too, lol) and learn more about and make Viking Age utility and belt knives, particularly piled construction or butt welded wrought/steel combinations. These relatively simple knives (more like deceivingly simple knives) fascinate me. Massive amount of shop clearing going on, thrown out huge quantities of crap (and in the course discovered things I have no idea why I bought a decade ago, like why do I have a two lb. bag of powdered yellow ochre???) It's kind of like Christmas, uncovering neat stuff I forgot I even had!

 

As part of this I have boxes of Kaowool that pesky rodentia got into that I need to salvage and seal up in better containers as well as a 55 gallon drum heat treating forge that was never coated that I need to make safe (at the time Don posted about making these on his original website it was commonly believed that ceramic fiber in this type of construction, with little risk of mechanical damage, was relatively safe). I definitely need to coat this now, it's an invaluable tool for heat treating and it needs to be safe to use. Fortunately it was only used three or four time and it was outside in the open.

 

Great! As a bearded individual I started researching PAPR filter masks, tons of great information here in the forums on them and I had decided on the 3M Powerflow as it was only a bit more expensive than the Tend Airshield Pro. Enter Covid 19, you pretty much can't buy any 3M systems now unless you are a front line Covid 19 responder. Looks like I will have to go with the Trend Airshield Pro after all. (I can't even begin to number the problems this pandemic has caused for us but I know they pale in comparison to the health risks and ultimate prices paid by others.) Stay safe all.

Edited by Guy Thomas

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Posted (edited)

The ochre was probably to use as solder block? As in, paint it on where you don't want solder to stick.

 

Research has actually shown uncoated kaowool is harmless as any other dust, see the thread up in Videos called "future lung cancer spokesman" for links.  No dust is great to breathe, but kaowool is not asbestos or silica.

 

Edit:  https://www.cdc.gov/niosh/docs/2006-123/

http://www.htiwcoalition.org/asbestos.html

 

Finally, I know what you mean about 3M stuff.  I have one, and it needs a new charger. They are available, but worth their weight in silver. At least I have a few (two)  N95 cartridges for it. Those are worth their weight in gold, if you can find them at all.

Edited by Alan Longmire
added links

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Thanks Alan, that first document will take a while to fully digest but a brief review seems to indicate that the common sense measures we take are more than adequate. I do need to check and see if the Trend Airshield Pro meets the 100 series filter recommendation. I do feel better about the drum forge at least as it was used for a limited amount of time and only up to 1450 degrees but I do want to consider coating. A process that when I get around to it I am going to be asking advice on just how to approach (i.e. using a stabilizer product, or not, wetting if needed, applying a thin saturation of satanite that soaks in, if it will soak in after being "fired" so to speak, or maybe skipping the satanite and only using a thin coating of one of the IR reflector products like Metrikote, I have some of that coming as my forge does need recoating and I really need to build a forge more dedicated to welding.) It also helps that I built a small blown blower for it that is very gentle.

 

I may have missed it but was there discussion about the changes ceramic fibers undergo as they are heated in furnace/forge situations?

 

You know, I "think" the ochre may have been intended for use perhaps as a polishing compound trying to bring out activity in hamons. I know I was screwing around with that at the time too. Trying to get back into this after an extended lay off is nearly as hard as starting all over again as if I were a beginner.

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I'd think the metrikote alone would be fine.  Larry Harley used a thin coat of Satanite, and that was a right bugger to keep the wool from collapsing until it was fired (picture me with a weedburner torch while Harley stands back with a long stick yelling "heat it there while I hold this!" "Hey, my stick's on fire!" and so on).  But it worked!  

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Posted (edited)
2 hours ago, Guy Thomas said:

I may have missed it but was there discussion about the changes ceramic fibers undergo as they are heated in furnace/forge situations

There are a few opinions about this.  A friend of mine once looked at some Kaowoll fibers under a microscope (electron?) and said that they looked just like asbestos fibers after being subjected to temps ~2100 F.  He's an ABS  MS, not a scientist, so I can't speak to his methods or how he compared the two.  


Here's a few excerpts from the CDC criteria that Alan referenced above that I feel are worth noting:

- According to Table 2-1 the diameter of post-production RCFs is 1.2 μm – 3 μm.  Cheng et al. [1992] analyzed an air sample for fibers during removal of after-service RCF: (RCF that has been subjected to greater than 1,800 F (~1,000 C) and has partially converted to the silica polymorph cristobalite) and found fiber diameters as small as  0.5 μm (Pg 15-16).

Longer and thicker (>3.5 μm in diameter) fibers are preferentially deposited in the upper airways. . . and are generally cleared via the mucociliary escalator (blowing your nose and coughing up phlegm). Thinner fibers tend to maneuver past airway bifurcations into smaller and smaller airways - (Pg 91)

- NIOSH concludes that RCFs are a potential occupational carcinogen. Furthermore, the evidence of pleural plaques . . .observed in persons with occupational exposures to airborne RCFs is clinically similar to that observed in asbestos-exposed persons after the initial years of their occupational asbestos exposures – (Pg 108)

- NIOSH concludes that on a continuum of fiber toxicity, RCFs relate more closely to asbestos than to fibrous glass and other SVFs and should be handled accordingly. – (Pg 111)

- increased exposures to airborne fibers have been linked to pleural plaques, small radiographic parenchymal opacities, decreased pulmonary function, respiratory symptoms and conditions (pleurisy, dyspnea, cough), and skin and eye irritation.  Many of the respiratory effects showed a statistically significant association with RCF exposure after controlling or adjusting for potential confounders, including cigarette smoking and exposure to nonfibrous dust. – (Pg 89)

- the RCFC (Refractory Ceramic Fibers Coalition) recommends that workers wear respirators whenever the workplace fiber concentration is unknown – (Pg 96)

At a minimum, use a half-mask, air purifying respirator equipped with a 100 series particulate filter (this respirator has an assigned protection factor (APF) of 10) – (Pg 119)
- Respirators should not be used as the primary means of controlling worker exposures. Instead, NIOSH recommends using other exposure-reduction methods, such as product substitution, engineering controls, and changes in work practices. – (Pg 118)  

 

I read the last point above to suggest that coating the RCF with castable refractory (would that be a change in work practice or engineering control?) is better than relying on a respirator to protect yourself.

Stay safe and have fun.

Edited by billyO

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4 hours ago, billyO said:

Th

At a minimum, use a half-mask, air purifying respirator equipped with a 100 series particulate filter (this respirator has an assigned protection factor (APF) of 10) – (Pg 119)
- Respirators should not be used as the primary means of controlling worker exposures. Instead, NIOSH recommends using other exposure-reduction methods, such as product substitution, engineering controls, and changes in work practices. – (Pg 118)  

 

I read the last point above to suggest that coating the RCF with castable refractory (would that be a change in work practice or engineering control?) is better than relying on a respirator to protect yourself.

Stay safe and have fun.

 

Thanks billyO, out of curiosity where did you find the APF rating on the Airshield Pro? I'd been searching with little luck.

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1 hour ago, Guy Thomas said:

where did you find the APF rating on the Airshield Pro

Unfortunately, I didn't. 

 

If you're referring to:

6 hours ago, billyO said:

this respirator has an assigned protection factor (APF) of 10

that's merely what i quoted out of the CDC link Alan gave on Pg 119.  Sorry about the parenthesis, I guess that made it look like I inserted that info.   I read that as a P100 filter is equal to an APF10.  

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Thanks for sifting through all that, Billy.  It shows that a topcoat is still a good idea!

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16 hours ago, Alan Longmire said:

I'd think the metrikote alone would be fine.  Larry Harley used a thin coat of Satanite, and that was a right bugger to keep the wool from collapsing until it was fired (picture me with a weedburner torch while Harley stands back with a long stick yelling "heat it there while I hold this!" "Hey, my stick's on fire!" and so on).  But it worked!  

 

I can just see that! Sure wish I could have met him.

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Posted (edited)
2 hours ago, Alan Longmire said:

Thanks for sifting through all that, Billy. 

Not a problem, Alan.  Thank you for providing the link to the resource.  I've been relying on anecdotal evidence when trying to convince folks to treat RCF like asbestos, regardless of what the industry says, now I have the documentation to back up my warnings.   

(as an aside, while going through that, I was taken back to my college days and reminded how much I enjoyed going through research papers...now if only that were a critical industry)

Edited by billyO

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18 hours ago, billyO said:

would that be a change in work practice or engineering control?

That would be an engineering control.  They are recommended/required because they are passive, meaning you can't "forget" to use them like you can PPE.  

 

2 hours ago, billyO said:

I've been relying on anecdotal evidence when trying to convince folks to treat RCF like asbestos, regardless of what the industry says, now I have the documentation to back up my warnings.   

The more I read on them the more I am convinced that they are nothing like asbestos and people should absolutely not equate the two.  It is important to remember that it is virtually impossible to prove a negative result when it comes to health things.  When you see phrasing like:

18 hours ago, billyO said:

NIOSH concludes that RCFs are a potential occupational carcinogen.

That should probably be read like "we can't find that it does anything too bad, but we can't prove it is safe either".  In contrast, asbestos is more along the lines of "Well, this is clearly really bad for you.  Stay away at all costs!"  

 

It is also worth noting that every time NIOSH (or any group like that) are commenting on it, they are generally referring to people that are going to be working with the material for 40 hours per week.  Generally speaking, that doesn't apply to the things we do.  This is noted in the CDC paper on page 108:

 

The risk estimates incorporated multiple assumptions, including a human breathing rate of 13.5 L/min (considered light work) and multiple criteria for defining the length of time a worker could be exposed to RCFs over a working lifetime. Higher risk estimates could be expected if the assumptions more closely represented those used by NIOSH and OSHA: (1) a human breathing rate of 20 L/min and (2) a worker exposure duration of 8 hr/day, 5 days/wk, 50 wk/yr, from age 20 to 65 with the risk calculated beyond age 70 (e.g., to age 85).

 

Also on page 108:

Insufficient evidence exists to document an association between fibrotic or carcinogenic effects and the inhalation of RCFs by workers in the RCF manufacturing industry though these effects have been demonstrated in animal studies.

 

Where the animal studies were from a single high exposure:

Although the lung cancer risk estimates derived from the rat data are reason for concern, estimates of human risk for mesothelioma from the high incidence (41%) of mesothelioma in hamsters cannot be appropriately modeled since only a single exposure was administered in the study.

 

And from their conclusions section on page 110:

Studies of workers exposed to airborne RCFs show no evidence of excess risk for lung cancer or mesothelioma.

 

And from page 112:

Recognizing that RCFs are carcinogens in animal studies and given the limitations in deriving an exposure value that reflects no excess risk of lung cancer or mesothelioma for humans, NIOSH recommends that every effort be made to keep exposures below the REL of 0.5 f/cm3 as a TWA for up to 10 hr/day in a 40-hr workweek.

 

REL means Recommended Exposure Limit and TWA means Time Weighted Average.  0.5 fibers per cm^3 is A LOT.  If you are being exposed to that much for 40 hours per week then you are definitely doing something wrong.  They note that the REL for asbestos is 0.1 f/cm^3.  The OSHA PEL for Cristobalite is 20 million particles per cubic foot of air.  

 

So, if you are exposed to a lot of particles hanging in the air for 40 hours per week, 50 weeks per year, NIOSH thinks there is enough uncertainty in the safety of it that you should wear a respirator.  Common sense says if you are exposed to that much of ANY particle in the air you should wear one.  

 

In looking into this I found that zinc oxide fumes (you know, the stuff that comes off when heating galvanized steel) is 5.0 mg/m^3, which is really hard to compare to fibers / cm^3, but since we're talking about it and this is another common thing we see, I thought I'd share for informative reasons only.  

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I'll also add that all insulation wool should be coated to protect the wool.  No sense letting it wear out faster than it needs to from poking or abrasion (or rodents).  In normal operation of a forge (even with un-coated wool) there is certainly not enough exposure to worry about.  The potential problems are when lining, and even more so tearing out an old lining.  So limit your exposure there by wearing a respirator when doing that, and reduce the times you do that by coating your wool.  

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Posted (edited)

I'm not arguing with anything you say about what's in the report, Jerrod.  And will readily admit that I picked out the most damming statements about RCFs in the report, because I'm one who would rather err on the side of safety. 

But let's not flush the baby with the bathwater, so to speak, and I'll re-highlight:

20 hours ago, billyO said:

 NIOSH concludes that on a continuum of fiber toxicity, RCFs relate more closely to asbestos than to fibrous glass and other SVFs and should be handled accordingly. – (Pg 111)

On another forum, someone said something to the effect that if it were dangerous, the CDC, FDA, NIOSH, etc wouldn't allow it to be sold.  Really? What about cigarettes?  the Boeing 737 Max? and I could go on....

I guess I don't have as much faith as many that our regulatory agencies have as much control over commercial interests as I feel they should.  

 

 

Edited by billyO

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7 minutes ago, billyO said:

On another forum, someone said something to the effect that if it were dangerous, the CDC, FDA, NIOSH, etc wouldn't allow it to be sold.  Really? What about cigarettes?  the Boeing 737 Max? and I could go on....

 

But you didn't read that on THIS forum, because we're usually smart enough to realize this. :lol:  Common sense is not that common, but we seem to have an abundance of it around here. B)

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