# Curve in taping knives - which way to use where?



## dtbingle (Jul 19, 2017)

On these taping / joint knives, many have a slight curve when you look down the blade where the edges stick out a tiny bit.

*When do you hold the knife so that the edges are coming away from the wall and when do you use the knife with the edges pointing into the wall?*

Is it preference or is it recommended to use the knife one way or the other for specific uses?

For example, to skim coat a wall, having the edges pointing away from the wall makes sense to me to allow for easy edge feathering. However, I've also read some prefer the edges pointing in, and with slightly pressure, the blade becomes flat, and makes it easier to get an even coating.


----------



## MTN REMODEL LLC (Sep 11, 2010)

BINGLE...... I'm a GC, and do taping muding for small jobs, but not skim coat.

Are you talking about normal 4 to 14" blades/knives. Mine do not have any bend in their tip.

Are you maybe referring to a butt trowel....made with a slight curve in it for building mud tape coat over a butt joint...but there is only one way to use those.

Maybe larger skim coating blades are made different, (I always contract that if I need that). But heck, I've seen the guys do that with a 14 blade.) 

I'm subscribing, maybe learn something new.

Best


----------



## Nealtw (Jun 22, 2017)




----------



## MTN REMODEL LLC (Sep 11, 2010)

Nealtw said:


> https://www.youtube.com/watch?v=1ZGAnq3G79Q


Yes...That's what I was trying to explain above...thanks Neal.

I did not watch the full thing, but it says "great for a doorstop".

Well the thing works great for me. For guys who do it 4o hours a week, it is probably just as easy for them to use their straigt blades/trowels, but for me, I love the thing.

But you sure wouldn't use it for skimming. 

I watched a little more, I always knew that trowel as a first tape coat for Butt joints. I don't think it was ever intended for how he tried to use it.


----------



## Nealtw (Jun 22, 2017)

MTN REMODEL LLC said:


> Yes...That's what I was trying to explain above...thanks Neal.
> 
> I did not watch the full thing, but it says "great for a doorstop".
> 
> ...


Some one gave me one, we had it in the truck, it was fun to give the new guy when you were trowelling footings. The last one to try it figured out the joke and tossed it in the bush. :biggrin2:


----------



## siffleur (Aug 19, 2013)

dtbingle said:


> On these taping / joint knives, many have a slight curve when you look down the blade where the edges stick out a tiny bit.
> 
> *When do you hold the knife so that the edges are coming away from the wall and when do you use the knife with the edges pointing into the wall?*
> 
> ...


I think I know what you are talking about. Some mud knives are perfectly straight when you eyeball them from edge to edge and some have a slight, even curve that bows out one way and in the other way. Some mud knives are badly uneven and I just pass on those, but I like to have both straight and slightly curved knives in my arsenal. I use the slightly bowed knives with the edges slightly bowed away from the wall when I am trying to feather a skim coat. I rarely use these knives the other way around.

siffleur


----------



## stick\shift (Mar 23, 2015)

I like the center of the knife high (I guess this would be edges pointed down) when patching, as it helps get the edge of the patch close to the same height as the existing finish while allowing just a little room in the middle for the repair.


----------



## dtbingle (Jul 19, 2017)

siffleur & stick\shift,

This is exactly what I'm talking about. Not trowels, but knives. As you described, it seems like you would want edges tipped into towards the wall during maybe first or second coat over a taped joint. With a large enough knife, you could keep the bowed center of the knife near the tape line and the curve of the knife would feather it down to the tipped-in edges of the knife.

But then for a skim coat, you would flip it so that the edges tipped away from the wall to easily feather the edges while moving across the entire wall opposed to feathering outward from a single center line of a taped joint.

Proves difficult to capture with phone camera, but here's an attempt.
On the left is a 4 in wal-pro stainless steel joint knife. Blade is straight.
On the right is a 10 in wal-board stainless steel taping knife. There's a slight curve to it.


----------



## MTN REMODEL LLC (Sep 11, 2010)

I'll be damned....learn something new everyday....!!!!!!!!!!!!!!!!!!!!!!!!!!!

All my blades (except that trowel I love for butt joint first tape) are straight.

I had no idea they made a curved blade.... maybe that's not so strange as I'm a GC and have had the same blades for many/many years.

Seems the above explanations (out for skimming- in for butt or 1st 2ecd passes) makes good sense.

So, when you are using them, how do you keep in mind which curve you have/want.

Is it evedent enough you can just tell, or is the handle different colored or what.

I don't do enough, or expect to do enough in retirement, to probably go find those curved blades......but sure would be interesting to see how they handle.

Is a curved blade identified somehow, apart from looking at it.


----------



## MTN REMODEL LLC (Sep 11, 2010)

Another question, if they are curved, do they wipe off clean in the pan..???


----------



## siffleur (Aug 19, 2013)

MTN REMODEL LLC said:


> I'll be damned....learn something new everyday....!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> All my blades (except that trowel I love for butt joint first tape) are straight.
> 
> ...


When I go to buy a curved blade knife I look at the edge of all the knives on the rack and pick the one with the curve I like best. When the knife is smiling at me I know that I am using the correct side for skimming:











When the knife is frowning at me I know that I am using the wrong side of the knife:









siffleur


----------



## MTN REMODEL LLC (Sep 11, 2010)

siffleur said:


> when i go to buy a curved blade knife i look at the edge of all the knives on the rack and pick the one with the curve i like best. When the knife is smiling at me i know that i am using the correct side for skimming:
> 
> 
> 
> ...



great idea!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


----------



## siffleur (Aug 19, 2013)

siffleur said:


> When I go to buy a curved blade knife I look at the edge of all the knives on the rack and pick the one with the curve I like best. When the knife is smiling at me I know that I am using the correct side for skimming:
> 
> 
> 
> ...


Oops! Here is the side that lets me know I am using the wrong side:









siffleur


----------



## dtbingle (Jul 19, 2017)

Haha that's a neat trick. The wal-board knives have the logo on one side of the handle only, so I use that to keep track of which side is which.

No, they aren't identified in any way.

Yes, they wipe off clean on the pan. When you wipe against the pan, that small amount of pressure is enough to flatten the blade against the edge of the pan.


----------



## jeffnc (Apr 1, 2011)

Nealtw said:


> https://www.youtube.com/watch?v=1ZGAnq3G79Q



Kind of an odd video. At 2:10 he says you can't find curved knives. At 4:50 he says knives have a curve in them. The overlay text says "just the tips". Well, I can't say I know how these things are manufactured or marketed, but I have some that are curved (not just the tips) and some that are straight. I just look when I pick it up.


Now, a curved knife is more usable than a curved trowel, because you can flip it over and use whichever side you want. Also, a knife is more flexible than a trowel. So I find the curved knife is very useful to me in certain situations when I want build up, or want to make sure the tips don't dig in. And it's flexible enough so that I can keep or eliminate the curve depending on how hard I press.


----------



## jeffnc (Apr 1, 2011)

MTN REMODEL LLC said:


> So, when you are using them, how do you keep in mind which curve you have/want.
> 
> Is it evedent enough you can just tell



Yes granted you have to take a sec to look. I never bothered marking them.


----------



## jeffnc (Apr 1, 2011)

MTN REMODEL LLC said:


> Another question, if they are curved, do they wipe off clean in the pan..???



Yes they are flexible enough you can press out the curve.


----------



## Jimmy O (9 mo ago)

dtbingle said:


> On these taping / joint knives, many have a slight curve when you look down the blade where the edges stick out a tiny bit.
> 
> *When do you hold the knife so that the edges are coming away from the wall and when do you use the knife with the edges pointing into the wall?*
> 
> ...


Taping knives should have a curve to them, See: SECRET Drywall Taping Knife Feature
If you knife does not have a curve, here how to create one.


dtbingle said:


> On these taping / joint knives, many have a slight curve when you look down the blade where the edges stick out a tiny bit.
> 
> *When do you hold the knife so that the edges are coming away from the wall and when do you use the knife with the edges pointing into the wall?*
> 
> ...


Your knife should have a curve in the blade. See: SECRET Drywall Taping Knife Feature. So too your trowel: Why is a drywall trowel curved?


----------



## Jimmy O (9 mo ago)

Jimmy O said:


> Taping knives should have a curve to them, See: SECRET Drywall Taping Knife Feature
> If you knife does not have a curve, here how to create one.
> 
> Your knife should have a curve in the blade. See: SECRET Drywall Taping Knife Feature.


For tips on bending knives see: 




See also:
how to bend curve in taping knife - Google Search


----------



## Old Thomas (Nov 28, 2019)

On butt joints, I use a curved 10” knife for the first coat to get build up on the joint. Then on the second coat I use a straight knife to feather out the edges, resulting in a 20” or so wide compound area.


----------



## finisher65 (Apr 7, 2019)

I always held a knife with the same side of the handle against my palm for the life of the knife. Once it breaks in you can feel if you're holding it in the correct orientation


----------



## IcarusTECH (10 mo ago)

I put a lil domed head screw in the handle by the thumb area of the side that is good to use. I can feel it with my thumb when I pick it up without even needing to look...


----------



## Sir MixAlot (Apr 4, 2008)

I did a video about this drywall knife feature.


----------

