Harbor Freight Black Compound

[Rennd]

Do you guys know what grit it is supposed to be? I would guess 3um, but I'm not sure. Also, what is the abrasive agent? SiC?

 

[HeavyHanded]

You can almost guarantee the abrasive is aluminum oxide. Very few compounds use silicon carbide - is generally used more for lapping, and cutting where it can be applied to a wire etc.

Binder is almost certainly stearin - a vegetable (and possibly animal) based tallow.

Grit size would need to be checked with a microscope but is probably in the 30u range - at least the Ryobi, Dico, and older Sears blocks were all about that size. The tube looks a lot like the stuff that Sears is currently selling (I tried to find it on their website but the search function is dreadful) but with a different label.

I have zero personal experience with the Harbor Freight stuff...

 

[Rennd]

I've used it on balsa and the resulting edge is near mirror, so it has to be fairly fine. 5-8000 grit jis, I'd estimate.

 

[HeavyHanded]

I've used it on balsa and the resulting edge is near mirror, so it has to be fairly fine. 5-8000 grit jis, I'd estimate.

The others I mentioned all leave a satin finish, even on a fairly soft backing. To be near mirror I'd say your first guess is close, 3u or so.

 

[Bill DeShivs]

As a rule, black compound is emery-a coarse, cutting compound.
Green, white, or red will be much finer.

 

[Rennd]

As a rule, black compound is emery-a coarse, cutting compound.

Green, white, or red will be much finer.

Don't worry, I know that, haha. I'm trying to figure out if I have something in the 3um range.

 

[Obsessed with Edges]

I've used it on balsa and the resulting edge is near mirror, so it has to be fairly fine. 5-8000 grit jis, I'd estimate.

The others I mentioned all leave a satin finish, even on a fairly soft backing. To be near mirror I'd say your first guess is close, 3u or so.

Don't worry, I know that, haha. I'm trying to figure out if I have something in the 3um range.

Those descriptions very closely mimic what I've seen in the black 'Emery' compound I've been using, from Ryobi, and labelled at 1-3 microns. Works very fast and leaves a very near-mirror finish. I've used it on leather and paper-over-wood, with similar results (faster on harder backing). I don't know if it's even available from them anymore, as the Ryobi that HH has mentioned in the past sounds coarser, and Ryobi's packaging (at least) is different nowadays. I recently picked up a tube of Sears' black, and it does seem coarser in finish, maybe approximating the 'satin' described by HH. Interestingly, when reading this thread and looking online at Harbor Freight's online listings, their packaging (plastic tube) looks identical to the stuff I found at Sears, sourced from China, as I assume the HF stuff is. Priced about the same, too. Makes me wonder if Sears and HF may be sourcing it from the same supplier.


David

 

[HeavyHanded]

Those descriptions very closely mimic what I've seen in the black 'Emery' compound I've been using, from Ryobi, and labelled at 1-3 microns. Works very fast and leaves a very near-mirror finish. I've used it on leather and paper-over-wood, with similar results (faster on harder backing). I don't know if it's even available from them anymore, as the Ryobi that HH has mentioned in the past sounds coarser, and Ryobi's packaging (at least) is different nowadays. I recently picked up a tube of Sears' black, and it does seem coarser in finish, maybe approximating the 'satin' described by HH. Interestingly, when reading this thread and looking online at Harbor Freight's online listings, their packaging (plastic tube) looks identical to the stuff I found at Sears, sourced from China, as I assume the HF stuff is. Priced about the same, too. Makes me wonder if Sears and HF may be sourcing it from the same supplier.


David

I have some of the newest Sears black and its plenty coarse. They have a next kick up that is more of a pale grey and its probably in the 3u range. Those tubes do look similar but I can't imagine they're the same thing. It doesn't take much to have some stuff formulated - when I spoke to Dico the salesman told me a minimum $1500 order could me a custom formulation. Sears and HF could easily be having their stuff mfg by the same outfit to different specs.

Am glad I have access to a strong microscope - takes a lot of the guesswork from figuring what goes into some of these materials.

 

[dkb45]

I have the HF black and it is finer than 6k. It has worked wonders for me refining my edges. I have since moved on to a black compound from Menard's, and it works even better. It may be a more uniform grit size, because it works faster and gives a sharper edge.

Bottom line, if you can't afford/don't want to buy the expensive diamond compounds, using the black from HF is perfectly fine. Only problem I had was that the binder made it extremely tough to apply, but heat may be able to fix that.