Fiberglass insulation killed my knife

[Seminarian]

Am I an idiot for not knowing that cutting attic insulation with my Kershaw JYDII was a big mistake? I now am in the market for a sharpening system, because at the moment I am not sure my Kershaw will cut butter.

 

[Rat Finkenstein]

Knives get dull, Period. Anyone who has a knife needs a way to sharpen it.

 

[sodak]

No, you're not an idiot, if you need to cut something, you cut it. Fiberglass insulation will dull any knife faster than almost anything else I can think of, except for maybe drywall. Rat has it right.

 

[Seminarian]

Good reminder. I guess I should be somewhat glad that my knife took one for the team by doing what it was meant to do. I am just a bit surprised how fast it went from being dangerously sharp to seemingly worthless.

 

[Troop]

:thumbup: Learn to freehand sharpen on a benchstone; you won't regret it. It just takes A LOT of perseverance.

 

[Peter_E_Ryt]

:thumbup: Learn to freehand sharpen on a benchstone; you won't regret it. It just takes A LOT of perseverance.

However, you'll want a cheap knife to learn on. If you want instand gratification with quick, easy, and mostly uniform results the first try, go for the sharpmaker.

 

[Cougar Allen]

Welcome to Bladeforums!

 

[yablanowitz]

Guess what? Fiberglass fibers are harder than steel. They eat up edges in a heartbeat, kind of like cutting sandpaper from the abrasive side. Next time, you'll know. I made a really ugly knife long ago just for cutting fiberglass insulation when I was doing a lot of that, just to save my good knives.

I agree that learning freehand sharpening is a worthwhile undertaking. No knife stays sharp forever if you use it.

 

[Esav Benyamin]

Get a Sharpmaker. Learning how to use it with the DVD will teach you a lot about what sharpening really means. It will also provide you with a quick and effective device for maintaining a good edge on your knives.

Once you've mastered the Sharpmaker's upright V, take the rods out, turn the base upside down, and lay the rods in the grooves. Voila -- instant benchstone.

For a knife that's been through what yours has, a benchstone is best, especially a diamond stone. But it takes time to learn to do it right.

I suggest practicing on old paring knives, or pick up a couple of cheapies, like Moras or Sodbusters in high carbon steel.

 

[_habit_]

However, you'll want a cheap knife to learn on. If you want instand gratification with quick, easy, and mostly uniform results the first try, go for the sharpmaker.

He could just send his knife to Kershaw and have them sharpen/replace it (free, you just pay shipping there), while waiting for his benchstone to arrive

 

[me2]

A very coarse hone may be beneficial. I've heard of people using Old Hickory knives and files to sharpen them for cutting insulation. The knives done last long, but they cut a bit longer with the coarse edge, and are cheap to replace.

 

[Esav Benyamin]

The right tool for the job ... nothing wrong with using a beater for rough work, as long as it will get the job done.

It can be a bit of a shock the first time a good knife goes dull. Get used to it. Any knife will dull eventually with use. I've sharpened a few Sebenzas, one of them several times, because I use it a lot, and sometimes on coarse materials.

Even using expensive knives lightly, you should still know how to put different kinds of edge on each. It's easy once you learn how.

 

[Cliff Stamp]

A very coarse hone may be beneficial.

Yes and get the edge very thin, 0.005" thick or so is a huge benefit. The standard polished very thick and obtuse edge you will find on such knives as noted in the above will only make a few cuts and then be next to useless. Also don't cut on concrete flooring, a lot of people do that as well when cutting insulation.

-Cliff

 

[Troop]

He could just send his knife to Kershaw and have them sharpen/replace it (free, you just pay shipping there), while waiting for his benchstone to arrive

But, that would be cheating! No fair.
Sending your knife back to the factory is for neophyte Zen-Sharpeners! In fact, upon more careful examination of this matter, sending your knife back to the factory wouldn't even allow you entrance past the monastery gates of the Shaolin Sharpening Masters Temple. You are unworthy.

 

[siguy]

It can be a bit of a shock the first time a good knife goes dull.

this is true. though i have been using knives for some years now, and sharpening them to actually be sharp in the last year or so, i had never really dulled a knife before earlier this week. i was building a handle out of some purple heart wood for an old knife i am fixing up. i used my SAK to shave a little bit off of the block to take it down in size. i really hardly even used the blade, and after when i checked it for sharpness, i found that i had actually flattened the edge where i had cut. before this the knife could shave hair.

i was shocked, but i am over it. i started carrying a "beater" knife a few weeks ago, for abusive tasks that would dull my cutting knives. the cutting bevel is thicker and stronger than my knives that are ground for cutting. this is the knife that i would use to cut holes in coffee cans for emergency cooking pots. i would never do that with any of my other knives.

keep a knife for cutting things that you don't want to ruin your other knives, and keep a knife for cutting things that won't destroy the edge.

or learn how to sharpen, fast.

 

[T. Erdelyi]

To cut attic insulation use a 2"X4" on a piece of plywood and a Stanley Razor Knife, razor blades are cheap and you don't risk ruining the edge on your EDC.

Also learn to sharpen freehand and you'll never be without a sharp knife.:thumbup:

 

[Bigfattyt]

Fiberglass is just that....glass pulled into long, thin strings of actual glass

alumino-borosilicate glass in super thin strands.


It will kill any edge quickly.

 

[Alberta Ed]

Olfas are great for cutting fiberglass and can be resharpened.

 

[Obsessed with Edges]

(Realizing this thread is nearly 15 years old, but it's still pertinent...)

I sort of look at the 'initiation' of a knife's edge in fiberglass as a perfect lesson in abrasive wear and a rite of passage in sharpening. It really opens the eyes to the concepts of material hardness and how different materials relate in that way. Once seen, some of the pieces of the sharpening puzzle begin to fall into place. My 'lesson' came in using an inexpensive double-edged 'duct knife' to cut some pink insulation - and it produced the same results. But it's a good way to force one past the fears of learning sharpening. It's certifiably dull now, and it MUST be fixed.

 

[catspa]

I’ll be cutting drywall today with a Stanley 499, but for glass batts I often use a beater 8” kitchen slicer sharpened with a file. Reaches through an R30 batt, I don’t care about cut quality.

Parker