Diamond paste

[steveclarkus]

If it works for you Kirk great. But my understanding is it's what gets embedded in the balsa that polishes the edge not what's rolling around on the top of the surface. I may be wrong though my misses tells me that often

Very true.

 

[Biltong & Boerewors]

I am in Scotland and after getting by with sub-standard balsa strops decided to bite the bullet and do it right. Very happy with the results.

Here are some links to get everything you need in the UK:

Acrylic substrate:

I ordered the 15mm A3 size. When you check out there is a section for comments to the seller. In this section I asked them to cut it length-wise into 4 equal strips.

CUT TO SIZE Clear Acrylic Perspex Plastic Sheet Greenhouse Glass Replacement | eBay

• Greenhouse Windows. Clear Acrylic sheet has unique physical properties and performance characteristics. Clear Acrylic sheet – PMMA – uv stabilised. • Protective Film Covering Both Sides. Minimum width of cut is 75mm.

go.skimresources.com

This is how they arrived:

I presume you have the diamond paste, if not here is a link to .1 micron paste (on their site it is called 1/10 micron paste) which is the difficult one to find:

RS PRO Grey Diamond Paste 1/10μm Grade , 10ml Bottle | RS Components

go.skimresources.com

Here is a cheaper one from Japan, but I can't vouch for it, as I didn't use it:

Japanese Diamomd Lapping paste 10g, Micron 0.1- 40 Abrasive Polishing High end | eBay

It is of very high quality Japanese made. The results that can be achieved are superb. These pastes when applied to leather give great results. 0.25 micron 0-1/2um 100000#. Below is a list of sizes in micron and equivalent grits.

go.skimresources.com

Balsa wood is plentiful, but go for a thin, 5-6mm thick size, the thicker, the more likely it will be to swell.

Get some heavy duty spray adhesive to stick them together, works a treat and its easy to use.

The most expensive part is the acrylic, but it should last you a lifetime, and if you have to replace the balsa you can re-use the acrylic.

 

[rbscebu]

@Biltong & Boerewors if you find your balsa strops a bit thin (being about 20mm thick in total) you can glue some balsa to the underside of the acrylic. I painted my underside balsa with a coloured acrylic paint. That helps to protect the underside balsa and prevents me mistaking it from the stropping surface.

 

[Biltong & Boerewors]

@Biltong & Boerewors if you find your balsa strops a bit thin (being about 20mm thick in total) you can glue some balsa to the underside of the acrylic. I painted my underside balsa with a coloured acrylic paint. That helps to protect the underside balsa and prevents me mistaking it from the stropping surface.

My strops feel good in the hand, I still have all my fingers. My balsa is a bit thicker, 10mm if I remember correctly, but I am aware of the risk of swelling, so I will lap them whenever I get a suspicion of swelling, or routinely after refreshing them for a third time.

So far only the .1micron needed refreshing once. They are about 4 months old.

Something else to add, my .1micron strop tended to get sticky, and yes I tried using less diamond paste, as advised, but I suspect it's the suspension oil in the paste that oxidises and becomes sticky. I found a solution that works for me - when I apply the paste I make a solution of paste and clean mineral oil, and then apply the thinned solution. Seems to give good stropping results and it doesn't get sticky.

 

[rbscebu]

My strops feel good in the hand, I still have all my fingers. My balsa is a bit thicker, 10mm if I remember correctly, but I am aware of the risk of swelling, so I will lap them whenever I get a suspicion of swelling, or routinely after refreshing them for a third time.

So far only the .1micron needed refreshing once. They are about 4 months old.

Something else to add, my .1micron strop tended to get sticky, and yes I tried using less diamond paste, as advised, but I suspect it's the suspension oil in the paste that oxidises and becomes sticky. I found a solution that works for me - when I apply the paste I make a solution of paste and clean mineral oil, and then apply the thinned solution. Seems to give good stropping results and it doesn't get sticky.

I re-lap my balsa flat each time I re-paste it. Re-lapping then only takes off a fraction of a millimetre. After about 6 re-laps (once every 3 or 4 months), my 8mm thick balsa is down to about 7mm thick. It should last me another 10 or so years at current usage rates.

I thin my paste down with alcohol before applying it to the balsa. My 5g tubes of paste are now down to about 4g. Looks like I will need more diamond paste in about 2030.

 

[Tony Miller]

I can relate to the "sticky" issue. When I used to offer pre-pasted paddle and bench strops the paste I used was water based and dried within hours. The supplier later changed the formulation (but swears they did not) and it felt oily and never truly dried and left a sticky surface. The manufacturer also made oil based abrasive and I questioned repeatedly if there was a mix up or issue and they said no change, no mistakes. I really did not like the sticky feel and stopped using their materials.

 

[Biltong & Boerewors]

I can relate to the "sticky" issue. When I used to offer pre-pasted paddle and bench strops the paste I used was water based and dried within hours. The supplier later changed the formulation (but swears they did not) and it felt oily and never truly dried and left a sticky surface. The manufacturer also made oil based abrasive and I questioned repeatedly if there was a mix up or issue and they said no change, no mistakes. I really did not like the sticky feel and stopped using their materials.

In my case the strop is fine just after pasting, but becomes sticky within a two to three week period. That's why I think the oil base changes with time for whatever reason, probably reacting to air.

Another possibility can be that the tallow residue left on the razor from the shaving soap is rubbing off on the strop. If it gets sticky again I should maybe try giving it a rubdown with alcohol which will remove any fatty/oily deposits, but won't remove the paste that is imbedded in the balsa.

Problem with stickiness is that when you do the very light stropping the razor starts jumping.

Thinning it with mineral oil seems to do the trick, maybe just provides some lubrication. I leave it for a few hours, give it a good hand rubbing, then wipe all remaining oil/paste off with a paper towel. In most cases you just have to trust there is enough diamond paste on it, because it barely leaves any visible sign of it.

 

[Darth Scandalous]

Interesting, I've noticed my .5 strop gets a little sticky. It also loads up with swarf much sooner than the others. I got my pastes from Tech Diamond Tools.

One other variable is the actual balsa. One of my pieces is tighter grained and a little harder than the others.

 

[Biltong & Boerewors]

Interesting, I've noticed my .5 strop gets a little sticky. It also loads up with swarf much sooner than the others. I got my pastes from Tech Diamond Tools.

One other variable is the actual balsa. One of my pieces is tighter grained and a little harder than the others.

Same here the .5 and .25 builds up swarf much quicker than the .1.

Considering the .1 sees daily use and the others very occasional use, I hardly see any swarf on the .1.

That is to be expected to some degree as it's finer, but he lack of swarf has made me doubt the quality of my .1 paste, so I bought from another supplier, but find the same. The stickiness, unfortunately is also the same, but much improved after diluting with mineral oil.

Found the same with the balsa, different grains, but in my mind the looser grain allows the paste to settle in the grooves, so it should be a good thing.

In the end regardless of my doubts, and small issues, it works, and it works very well.

 

[JPO]

There is a blog which i am not allowed to refer to. He indicates that at some grit level the substrate is more important then the particle size. Is there any point in using finer grit then 0.25 micron on balsa, or do you need to apply finer stuff on other substrates. I have only tried CBN spay on balsa, 0.25 and 0.1 micron. I did not see/notice any improvement with the 0.1, but when i sprayed it on a leather strop things changed. The edge got a little smoother, but to sharp for my taste. An Hart steel 7/8 razor was at that time a little to much for me with that type of edge.

 

[Darth Scandalous]

There is a blog which i am not allowed to refer to. He indicates that at some grit level the substrate is more important then the particle size. Is there any point in using finer grit then 0.25 micron on balsa, or do you need to apply finer stuff on other substrates. I have only tried CBN spay on balsa, 0.25 and 0.1 micron. I did not see/notice any improvement with the 0.1, but when i sprayed it on a leather strop things changed. The edge got a little smoother, but to sharp for my taste. An Hart steel 7/8 razor was at that time a little to much for me with that type of edge.

I think it makes a difference. .25 balsa is not a comfortable shave compared to finishing on .1.

In terms of sharpness, it may not be much different, though. I don't see much if any change in HHT results between the .25 and .1. To my mind, the .1 balsa is there to make the. 25 edge tolerable.

 

[rbscebu]

Of course everyone's shaving experience is different but I find that shaving off a 0.1μm balsa strop is smoother and more comfortable than either 0.5μm or 0.25μm. Just find what you like best and use it.

As for paste "stickiness", I experience that towards the 3-month daily use mark with my 0.1μm balsa strop. It is then about time to re-lap and apply new paste. I haven't had a lot of new blades over the paste year so my other balsa strops don't get a lot of use.

 

[JPO]

I think it makes a difference. .25 balsa is not a comfortable shave compared to finishing on .1.

In terms of sharpness, it may not be much different, though. I don't see much if any change in HHT results between the .25 and .1. To my mind, the .1 balsa is there to make the. 25 edge tolerable.

Maybe i need to revisit my balsa strops. They seem to work good on harder steel. Have anyone compared CBN against diamond?

 

[rbscebu]

Maybe i need to revisit my balsa strops. They seem to work good on harder steel. Have anyone compared CBN against diamond?

All of my blades work well from diamond pasted balsa. They vary from soft (about 56 RHC) to very hard (close to 70 RHC). It was including short X strokes that was the game changer for me in shave comfort.

I believe that a few have compared diamond verses CBN, but not me. None, to my knowledge, have noticed a discernible difference.

 

[Tomo]

It was including short X strokes that was the game changer for me in shave comfort.

^^^^ +1

A totally different edge after short cross hatched x-strokes to finish.

 

[BDF]

This is the first time I have heard anyone mention balsa varieties, and it does varies quite a lot between pieces. It ranges from nearly white, with no grain to medium dark (about the color of oak) with a significant grain. The lighter it is the softer and less dense it is. I find the best balsa for use as a pasted strop is hard balsa. It seems like the abrasive paste gets lost or buried in very soft balsa.

Some may find this interesting or not.... but it is free Balsa is graded into densities before it is sold for uses such as building model airplanes. It comes in three grades usually, soft, medium and hard. All have their uses; soft balsa is easy to plane, carve and sand. Hard balsa is the strongest but also the heaviest. Hard balsa does not bend well as it usually splits. That is where medium balsa shines when trying to get it to conform to some shape, such as wing skins.

<snip>

One other variable is the actual balsa. One of my pieces is tighter grained and a little harder than the others.

 

[rbscebu]

@DBF I agree with you that the type (grade) of balsa can affect the pasted balsa stropping. Unfortunately, most hobbyshop vendors don't appreciate the difference and their stock is not graded. I just have to select by eye and comparing the weight of the pieces available. My preference is for about a medium grade balsa, the best (or worst) of both worlds.