Filling Pitted Round Knife with Epoxy for refurbishing

[AlamoJoe2002]

I have an CS Osborne, Newark NJ,  Round Knife due in which will be my 1st round knife. The metal blade is pitted. Hopefully I can work on the blade without removing the handle. I would like to remove the rust using electrolysis by suspending the blade into solution and adding current to remove the rust. Then instead of removing material to the lowest pitted level, I propose to fill in the pitting with a metal epoxy, then begin profiling the blade by hand using various grits of sandpaper.

Do you have a few words of guidance for the electrolysis rust removal? 

How about products for filling in the pitted metal?

How do I protect the manufacturing stamp when I begin to sand down and profile the blade? 

I also like the idea of reworking the #70 Blade into a more custom knife similar to the Terry Knipschield non-symmetrical Round Knife.

Then again, I want my first knife sharp, shinny, and a pleasure to use as it will be mine!

Joe

[mike02130]

  Good luck.  Make sure to show us the result.

[AlamoJoe2002]

I found this product which is sold as a metal epoxy designed for pitting.

https://www.belzona.com/en/products/1000/1151.aspx

I have no idea the cost...

Joe

[Tugadude]

The Belzona material will be very expensive.  You could buy a Knipshield knife and have money left over probably.  

[YinTx]

I've used belzona in industrial applications before.  Some versions are machineable, etc.  They typically require special metal prep to ensure proper adhesion, and heat treatment to cause the polymer to crosslink for strength and other desired properties in industrial uses.  It is expensive, I would presume prohibitively expensive for use on a knife. (as in one unit of material will cost more than a knife will).  If the pitting is in the blade edge, I don't think you'd be able to get belzona to sharpen and hold an edge for cutting purposes.

A cheaper alternative would be something like JB Weld if you wanted to experiment with the epoxy based fillers.

YinTx

[fredk]

imo the pitting is part of the history of the blade

To remove the corrosion - a conservator at the RAF Museum, Cosford showed me how just leaving the metal in a weak solution of citric acid for a long-ish period removes the corrosion. He showed me before and after examples of aluminium alloy, brass, copper, steel and iron. 

I've used the technique using lemon juice in water and leaving an old rusted up tool in it for a couple of months, renewing the solution periodically though.

Cleaning the blade back to shiney metal - various grades of wet & dry grit paper, starting with rough, 320 grade, thru to 2000 grade then polishing with toothpaste

2nd vote for JB Weld - if you really must

[Mulesaw]

If you want to do the electrolysis rust removing, here's what I have tried with success:

Mix water and soda (natrium carbonate) in a bucket
Put a piece of metal in the bottom of the container where you will be doing the electrolysis. I use an old piece of steel  netting.
Connect the positive terminal from a car battery or a battery charger to the metal in the bottom of the container.
Pour in the water/soda mixture
Suspend the rusted item in the mixture, it must not touch the metal in the bottom.
Connect the negative terminal from the battery or the charger to the rusted item.

After a bit of time (depending on voltage, concentration of the system etc), you will see bubbles and something like a layer forming on the surface above the rusted item. 
I let it sit for a day or so. Then remove the electrical connections and take the de-rusted piece out of the solution.
There will be a black layer on the surface that I normally remove with a scotch brite pad.

Note that some electronic type battery chargers won't work, presumably because they can't see any voltage at all and hence won't start. (I bought a charger from Lidl that did just that).
 

I have also de-rusted plane irons by immersing them in regular household vinegar over the night. Again the rust turns into a black powder that is removed with a scotch brite pad.
For smaller items such as a knife blade, I'd go with the vinegar.

I doubt that any of the epoxies such as Belzona or Wencon etc. will work for sharpening. I have used them for repairing worn shafts that would sit in a bearing, or pitted pump housings, but they are not metal, so I would leave the pittings and look at them as character of that particular knife.  

Bgrds

Jonas

[chuck123wapati]

8 hours ago, fredk said:

imo the pitting is part of the history of the blade

To remove the corrosion - a conservator at the RAF Museum, Cosford showed me how just leaving the metal in a weak solution of citric acid for a long-ish period removes the corrosion. He showed me before and after examples of aluminium alloy, brass, copper, steel and iron. 

I've used the technique using lemon juice in water and leaving an old rusted up tool in it for a couple of months, renewing the solution periodically though.

Cleaning the blade back to shiney metal - various grades of wet & dry grit paper, starting with rough, 320 grade, thru to 2000 grade then polishing with toothpaste

2nd vote for JB Weld - if you really must

after that final toothpaste polish he will be able to do one handed push ups lol

13 hours ago, AlamoJoe2002 said:

I have an CS Osborne, Newark NJ,  Round Knife due in which will be my 1st round knife. The metal blade is pitted. Hopefully I can work on the blade without removing the handle. I would like to remove the rust using electrolysis by suspending the blade into solution and adding current to remove the rust. Then instead of removing material to the lowest pitted level, I propose to fill in the pitting with a metal epoxy, then begin profiling the blade by hand using various grits of sandpaper.

Do you have a few words of guidance for the electrolysis rust removal? 

How about products for filling in the pitted metal?

How do I protect the manufacturing stamp when I begin to sand down and profile the blade? 

I also like the idea of reworking the #70 Blade into a more custom knife similar to the Terry Knipschield non-symmetrical Round Knife.

Then again, I want my first knife sharp, shinny, and a pleasure to use as it will be mine!

Joe

i wouldn't use electrolysis at all i use vinegar fast easy cheap and non toxic lol and works as well as anything. I would leave the pits alone and leave the patina you will never make a new knife out of an old one just one that is cobbled up looking. if the edge is pitted then no filler will fix that you will need to regrind the edge and that will take some power tools and alot of water not to ruin the temper. Any collector value is long gone if its that rough if there ever was any so you can do about anything you want to the blade shape. Good luck and post some pics when you get finished.

Edited May 29, 2021 by chuck123wapati

[chuck123wapati]

a prior thread that might help also.

 

[Bant]

Some pictures of the knife would, in my opinion, would be nice to see where the issues are.  I've never done the electrolysis, but I've used vinegar, which has worked, but the soak time varies. Two other possibilities; 1)  Contact Osborne and see if they might be of assistance and 2)  Seek out a pro who might be able to help.  From my perspective, if the cost of going that direction is affordable to rectify the situation, it may well be a good approach.

With the later, take a look at Bladeforums.com.  If posting another site for help is verbotten I apologize.