What grit to sand down balsa strop?

[Tea-bott5000]

I have an old chunk of balsa that I had some diamond paste on for knives years ago. I just ordered some some chromium oxide and iron oxide pastes to augment my stropping game, and I wanted to re-use that piece of balsa. How fine should it be sanded if I want to start over?

Thanks

 

[Slash McCoy]

Will you be using it for knives, or razors?

If for razors, be sure to glue the balsa to a base that positively will not flex and will not warp and is light enough to hold in hand. That basically means 3/4" thick acrylic. After assembly, depending on what shape the balsa is in, you might try 200 grit, then 400. If the balsa is very thick you might first saw off the top 1/8" or so on a bandsaw or table saw. The paste tends to load up the sandpaper and so if it is practical to avoid sanding on the pasted surface, then do so. If it is really grungy start with 100 grit just to get down into virgin balsa, then start progressively lapping. Again, for razors, glue a whole sheet of sandpaper to a very flat surface, preferably cast acrylic plate or a verified to be flat sink cutout from a polished granite countertop or a verified flat polished granite or marble floor tile. Ceramic will definitely not be flat enough. Not wood, either. And I would MOST HIGHLY recommend diamond paste, not the old red and green. See the pasted balsa strop thread.

For knives, most likely you can just wing it. Not so critical. But it doesn't hurt a thing to get particular about the details. You will likely get incrememtally better edges. Me, TBH I do not like to go finer than a 1k grit stone or sandpaper or 15u lapping film, for knives. I find the toothy edge with a well executed bevel gives me very good cutting power, and taking the progression out to 12k and then pastes does nothing for most knives. Specialized sushi/sashimi knives being the main exception.

 

[Tea-bott5000]

Thank you for the detailed reply. In this case the balsa is for razors. I'm just learning how to hone my own, and have so far taken some completely edgeless ebay razors to 'meh' shaving quality on a Naniwa 10k. Thought I'd add some green and red to the mix to see where that goes. My hope is that once I'm technically sound enough to get a decent shaving edge from 10k + pasted balsa I'll think about adding a finer stone.

Knives I take between 3k and 6k, depending on their function.

 

[Slash McCoy]

Thank you for the detailed reply. In this case the balsa is for razors. I'm just learning how to hone my own, and have so far taken some completely edgeless ebay razors to 'meh' shaving quality on a Naniwa 10k. Thought I'd add some green and red to the mix to see where that goes. My hope is that once I'm technically sound enough to get a decent shaving edge from 10k + pasted balsa I'll think about adding a finer stone.

Knives I take between 3k and 6k, depending on their function.

Then see this thread and all of the linked threads, read them beginning to end. If you can follow detailed instructions to the letter, your days of meh razor edges will be over for less than the cost of a good finisher.

Newbie Honing Compendium

I find myself often linking just a few threads rather than give a long winded explanation that takes me 15 minutes to type on my phone. So, here are my favorite threads to suggest that newbies read if they are interested in making their razors sharp. Lapping film, try it. Setting the Bevel...

www.badgerandblade.com

 

[RumpleBearskin]

Just did the annual lapping if my pasted balsa set. Sanded with 220, then 320, then 400 on a granite slab. Silky smooth and flatter than a pancake.

 

[steveclarkus]

I do a few laps with 80 grit to get it flat quickly then 220 and a few on 400.

 

[dsteidtmann]

I use a balsa strop progression as described in the balsa strop thread. When I re-flatten my balsas, I use 80g grit to remove the gunk, then 220, then 400. Higher than that hasn't seemed useful to me. I use a brass bristle brush on the 80 because the old grease and stuff tends to clog the sand paper quickly, and the bristle brush cleans it right off. One thing I would recommend is sanding your finest diamond paste balsa all the way through all the sand paper grits first, then take the next finest diamond paste balsa all the way through the sand paper grits. For me, that means I take my 0.1um balsa strop through the 80 grit paper, then the 220, then the 400. Then I brush off all the sawdust and do the 0.25um strop. My thought is, that if I get smaller diamonds on a coarser strop it's no big deal, but getting a bigger diamond particle mixed in with smaller diamonds probably isn't great.

 

[Levue]

80 - 180 - 400 it's what I used.

 

[rbscebu]

I use an 80 to get the gunk off then 180 and finally 320 (the finest non W&D readily available to me) to finish off. I'm happy with the results I get.

 

[davidjohnwalter]

Just did the annual lapping if my pasted balsa set. Sanded with 220, then 320, then 400 on a granite slab. Silky smooth and flatter than a pancake.

I USE A GRANITE WITH WET DRY PAPER TO LAP MY STONES THE FLATEST..DAVE

 

[smithabrian]

Just did this today on some 1/2” balsa planks. 400 grit paper allowed me to watch the mill saw marks slowly disappear as I sanded using a flat glass plate underneath. I found it helps to look at the wood at an angle under bright lights.


Sent from my iPad using Tapatalk

 

[Tomo]

I’ve set up a lapping progression on a large terrazzo floor tile 240, 600 and 1200 grit. I use the rolled sandpaper sheets. They are long and wide enough that the whole strop is always in contact with the sandpaper. I suggest cutting the rolls to size and weighing them down to flatten them before gluing to the tile. Selleys Kwik Grip contact spray adhesive on the back of the paper sticks them down well but allows them to be removed later. Works a treat. This might be over kill but everything worth doing is worth overdoing right?

I lap my 0.1u strop once a month. At this point the strop has seen 1,500 laps and is starting to darken a little. I’ve never used the 0.5 or 0.25 strops since initailly setting up my razor. I always notice the edge is a bit sharper after lapping. It cuts the hanging hairs that little bit quieter.

The only 0.1u diamond paste I could find is 50% concentration and it’s super thick and quite hard. I cut this with mineral oil on a plastic sandwich bag mixing it in with my finger. This makes it thin and spreadable and allows you to smooth out any clumps and chucks. I then use three fingers and dot the mixture all over the balsa. I then take a foundation makeup brush to pick up the last of the mix and gently spread in all of the dots. Once it’s even, I rub it in very gently with my fingers brushing off any little clumps. I then take a soft t-shirt rag and wipe off any excess. I leave this to sit for a few hours as the mineral oil soaks in. After that it is wiped clean again by hand and then a soft t-shirt rag.

It sounds like a lot of work but it’s probably only ten or fifteen minutes. I just finished this bad boy today. Smooth as silk and dead flat. I probably started with too thick of balsa but it’s slowly wearing down. This guy will probably go for a few more years.

 

[Slash McCoy]

I’ve set up a lapping progression on a large terrazzo floor tile 240, 600 and 1200 grit. I use the rolled sandpaper sheets. They are long and wide enough that the whole strop is always in contact with the sandpaper. I suggest cutting the rolls to size and weighing them down to flatten them before gluing to the tile. Selleys Kwik Grip contact spray adhesive on the back of the paper sticks them down well but allows them to be removed later. Works a treat. This might be over kill but everything worth doing is worth overdoing right?

I lap my 0.1u strop once a month. At this point the strop has seen 1,500 laps and is starting to darken a little. I’ve never used the 0.5 or 0.25 strops since initailly setting up my razor. I always notice the edge is a bit sharper after lapping. It cuts the hanging hairs that little bit quieter.

The only 0.1u diamond paste I could find is 50% concentration and it’s super thick and quite hard. I cut this with mineral oil on a plastic sandwich bag mixing it in with my finger. This makes it thin and spreadable and allows you to smooth out any clumps and chucks. I then use three fingers and dot the mixture all over the balsa. I then take a foundation makeup brush to pick up the last of the mix and gently spread in all of the dots. Once it’s even, I rub it in very gently with my fingers brushing off any little clumps. I then take a soft t-shirt rag and wipe off any excess. I leave this to sit for a few hours as the mineral oil soaks in. After that it is wiped clean again by hand and then a soft t-shirt rag.

It sounds like a lot of work but it’s probably only ten or fifteen minutes. I just finished this bad boy today. Smooth as silk and dead flat. I probably started with too thick of balsa but it’s slowly wearing down. This guy will probably go for a few more years.

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Your method is pretty close to The Method. Little wonder that it works for you. Yes the balsa is a bit thick but it's not a dealbreaker. You would be slightly better off with a thicker plate and thinner balsa because the balsa can swell unevenly even though it cannot warp because of the rigid plate to which the balsa is firmly attached.

I don't bother going finer than 600 grit but it isn't hurting anything to go finer. Just takes a little longer and adds a small amount to your sandpaper expenses. No biggie.

If that's what blows your skirt up I say it is just fine. From where you are, further refinement is approaching the point of diminishing returns closely enough.