I have tried chromium oxide on balsa and leather (paddle strop surfaces) using the Hand American "semi-paste" solution. In both cases, I have noticed that at first the surface seemed relatively smooth when stropping, then followed later by a more undulating surface felt along the length while stropping, after repeated (although not excessive) use. At first I thought it was the crox reacting with tannins in the grain of the balsa wood, but the effect with leather seems similar. What is the cause of this? It doesn't seem to occur with other pastes. And following this, why is crox so often recommended with balsa rather than other surfaces? Is it related to this effect?
Crox Questions
- Thread starter Alum of Potash
- Start date
You applied too much paste. Handamerican uses an agent in their compounds to keep their pastes from drying out. The moisture retention swells/raises the grain in the balsa and leather. More in the places it has been applied heavier.
CrOx is recommended for balsa because first the balsa provides a relatively flat surface and you're less likely to convex your edge. CrOx particles also have a less aggressive and jagged structure than diamond. They can sit closer to the surface (balsa) rather than embedded deeper on a cloth strop without cutting as aggressively as diamond would. A CrOx pasted cloth strop would be slightly less aggressive than a balsa strop and more likely to convex your blade edge because of the increased flex.
CrOx is recommended for balsa because first the balsa provides a relatively flat surface and you're less likely to convex your edge. CrOx particles also have a less aggressive and jagged structure than diamond. They can sit closer to the surface (balsa) rather than embedded deeper on a cloth strop without cutting as aggressively as diamond would. A CrOx pasted cloth strop would be slightly less aggressive than a balsa strop and more likely to convex your blade edge because of the increased flex.
- Thread starter
- #3
Thanks. I had thought that it might be too much paste as well, but I did try to use a light, even application in both cases, for what it's worth. Still, it may have been too much. Assuming it was at least even in application, the augmented moisture retention in places would then be due to surface (or chemical) irregularities in the wood and leather, no?
Assuming it was applied evenly then certain parts of the strop would be more absorptive than others for whatever reason.
If the undulations are not severe then, at worst, you would get a very slight convexing of the blade edge.
You could try flattening the leather strop with a bottle on a flat surface. To get the balsa even you would have to give it a few weeks from application of the paste to dry out completely and then sand/lap it flat.
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- #5
Thanks again. I rubbed my finger over the leather surface trying to smooth out and remove excess crox in this way (thoroughly washing my hands off afterwards) and this seems to have helped things in the short run. What I am noticing is that the undulating sensation coincides with a build up of swarf in certain areas, which again may be related to too much crox. I would try the bottle method on leather, except the other side of the paddle has suede with T-I alox/diamond and I don't want to mess this up with too much pressure from the other side. I have been using the paddle like this for several weeks and have had no detrimental issues with the edge afterwards, just the weird sensation. Perhaps a light application of a moistened sponge, or sanding and re-pasting of a lighter amount of crox might be preferable.
Yes, too much I find 2in x's work best and allow the surface leather, wood or nylon to polish the edge, wax on wax off. If you just want to experiment, a 5 gallon paint stir stick and a Chrome ox crayon... the 5 min chrome ox strop.
WD40 wil remove the chrome ox if you want to start over. Chrome Ox and nylon works best.
WD40 wil remove the chrome ox if you want to start over. Chrome Ox and nylon works best.
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- #8
Thanks. I've been thinking a moistened rag might do the trick.
Here is a video of my CrO on balsa technique.
Enjoy,
Gammaray
Enjoy,
Gammaray
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- Thread starter
- #10
Thanks, the presentation is quite clear. Seems like there is a lot of crox on your surfaces, compared to what I gathered others were saying. I have tried spreading crox on balsa like you show, and a lighter coat on leather glued to maple, and both cases, there is the irregular surface sensation of which I mentioned in my OP. My problem has to do with the surface and how much crox should be there.
The samples you see in my video are at varying levels of age and use. About once per year I lap my balsa on 2000 grit sandpaper atop a certified granite plate. This is probably overkill for balsa, but it is is the same setup (dry of course) that I use to lap my waterstones. The thin, small sample I introduce at the beginning of the video is on leather, which was glued under the pressure of the same granite plate for a couple of days. Balsa gets truer and flatter each time I do this. You will notice the block sample actually reflects light when I hold it at an angle because it is so flat and slick.
Lapping does not remove all the CrO. After lapping I reapply with a brush in liquid form, allow it to dry, and then start stropping. This process, repeated over time, embeds the CrO into the first mm or two of the balsa creating the deeper, darker look than when applied to a fresh piece of balsa.
CrO is self regulating on balsa as it will shed any excess during stropping as a green dust until it is fully embedded into the balsa.
I hope this offers some explanation to the appearance that you described.
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