Baking soda as a lapping compound?

[fj3fury]

I've been reading up on lapping lee molds, and have seen where some valve lapping compounds are too abrasive even the fine grits. I was thinking some before dragging out of bed how old tooth pastes used to be gritty and how that would be a good compound... but it's not made like that any more. I then remember my dentist say that baking soda eventually can wear enamel on teeth over time... So why not use it on aluminum? What do you guys think, and if the consensus is I'm half-baked I won't take offense. Sometimes I remember too much trivial info.

[deltaenterprizes]

Try "Barkeepers Friend"

[lesharris]

I recently Leemented my 6 cavity Lee's and I tried Barkeepers Friend.
It worked very well.
The pan i scrubbed in had some aluminum particles in it after I did 14 new and well used molds.
Barkeepers had a slight amount of gritiness to it.
Molds looked better than new.

[montana_charlie]

Baking soda may not 'wear' the enamel as much as it 'erodes' it in a chemical manner of speaking ... a reaction of some kind. But, I can't claim any knowledge of the subject.

The 'grit' in Bon Ami cleanser (feldspar) is about the mildest abrasive known to man. I use it in a homemade version of JB bore paste.
I have managed to get Bon Ami to lightly 'scuff' stainless steel pots and pans, but only with tenacious scrubbing.

CM

[94Doug]

I'd say it is a light abrasive as well. It is recomended to clean some pots and pans, like enamel cast iron. It might work. If you're spinning something in the mould at XXX rpm, it shouldn't take much.

Doug

[maglvr]

I use the toothpaste/baking soda combo in my molds all the time, great results!

[uscra112]

I've heard enough outright claptrap from dentists to last me the rest of my life and then some.

Baking soda (sodium bicarbonate) isn't an abrasive at all. But in an aqueous solution, it is alkaline and will attack aluminum quite readily. Sodas also bind with calcium carbonate, which is why washing soda (sodium carbonate) works to improve the action of soaps and detergents, when hard water is present. Any alkali will saponify grease, which is why it can help clean pots and pans.

Toothpastes are 50% insoluble abrasives, mostly silicas and related minerals. Abrasive, yes, but rather weak ones.

You can buy proper lapping compounds from www.mcmaster.com ... Aluminum oxide or boron nitride in a grease carrier work a whole lot better than toothpaste. I have 400, 600, and 800 in my cabinet, which I also use for bore lapping. A 2 oz. jar is a lifetime supply, costing about ten bucks.

[Maineboy]

I've smoothed out several Lee moulds by lapping them them with Soft Scrub.

[3006guns]

One more for Bon Ami....available at any grocery store and one can will last you a lifetime. For lapping mold cavities it's excellent, as you'd have to WORK at it to really do any damage. Also good when mixed with a light oil for removing mild rust from things.

[Flinchrock]

Baking soda may not 'wear' the enamel as much as it 'erodes' it in a chemical manner of speaking ... a reaction of some kind. But, I can't claim any knowledge of the subject.

The 'grit' in Bon Ami cleanser (feldspar) is about the mildest abrasive known to man. I use it in a homemade version of JB bore paste.
I have managed to get Bon Ami to lightly 'scuff' stainless steel pots and pans, but only with tenacious scrubbing.

CM

What kind of abrasive is in Bar keepers friend??

[Iron Mike Golf]

What kind of abrasive is in Bar keepers friend??

I don't know. But be aware it contains oxalic acid, so you don't want to let it set too long if you use it wet. I have used it on flea-market iron molds and liked the results.

[nanuk]

some use baking soda to "Sand Blast" aluminum. it apparently does a good job of cleaning chainsaw carbs, and can be washed out of the tiny jets.

so it must be a bit abrasive.


and BonAmi isn't available up here in my area.

[runfiverun]

i have used whitening toothpaste to smooth out steel molds.and have removed the blueing from the cavities easily enough.
if looking to polish an aluminum mold or even to gain a thousandth or so shouldn't be too much trouble with it.

[MikeS]

Another very fine lapping compound can be made by getting sublimed sulfur (it's available at most pharmacies) mixed with a light grade of oil. We used to use this when I was in the leather working machinery business to lap in parts when assembling new machines. One nice thing about it is that it's fairly easy to wash off using more of the same light grade of oil. In the industrial sewing machine market there's a light oil called Lilly White Oil, sometimes called stainless oil that's used to lubricate sewing machines so that if some of it gets on whatever is being sewed it won't stain the item, and that's what we mixed the sublimed sulfur with to make our lapping compound. We also used a powdered lapping compound (also mixed with the stainless oil) that was a bit coarser than using the sulfur, but still much finer than any of the clover type lapping compounds, I don't know exactly what grit it was, but it was sold by the industrial sewing supply houses in New York's garment district. I would imagine that either of these would work great for lapping a mould as they wouldn't remove much metal, and would leave the cavities with a mirror finish!

[MajorJim]

Anyone ever use rottenstone? I have used it in stock finishing - more of a polishing compound for the final finishes.

[sthwestvictoria]

I needed to Lee-lement a new .30 mold and couldn't find any abrasive. I did try a thin water and sodium bicarbonate paste and will not be doing it again.

The bicarbonate seemed to create a burr on the "trailing edge" - that part of the mold the boolit just spun past. I needed to cut this off with a blade.

I purchased some real grinding paste in a grease base the next day and achieved a much better result with clean mold edges.

[quasi]

someone here recomended the cleaner Comet for cleaning=deburring moulds. I have tried it and it works well for me.

[1Shirt]

All good suggestions, but to finish and put a great finish after the tooth paste, etc, jewlers rouge is the way to go!
1Shirt!

[wallenba]

Wow! I got curious about where it comes from and found this article on the net. http://www.madehow.com/Volume-1/Baking-Soda.html This stuff has a lot of uses and even stranger source. Find the paragraph about 'trona'. Very interesting read if your a geology geek.

[waksupi]

I use Diatomaceous Earth and light oil on my leather strop in the shop. Makes a good edge on my chisels.

[hiram]

I used rottenstone to lap a mold. I believe it is finer than pumice.

[lesharris]

Barkeepers Friend,and Bonami have worked well for me.

[legend]

WAKSUPI, thanks for the diatomaceous tip...i would not have thought of that.

[nodda duma]

From the optical fabrication world:

The most common compound for polishing and final figuring of precision optical surfaces is a cerium oxide slurry. I prefer zirconium oxide because it has a better feel. You can get it from universal photonics for about $20 a pound or on gotgrit.com I think. Mix about a table spoon into a cup of distilled water and wet polish the surfaces. You'll get a mirror finish on your metal.

Also look on McMaster Carr at their polishing sheets which go down to 2000 grit.

[nodda duma]

Wow! I got curious about where it comes from and found this article on the net. http://www.madehow.com/Volume-1/Baking-Soda.html This stuff has a lot of uses and even stranger source. Find the paragraph about 'trona'. Very interesting read if your a geology geek.

I used to live near Trona when I worked at China Lake. The place is a dump. There's a street there where every third house has burned to the ground...Good way for a poor Trona-ite to get enough money (insurance claim) to get out of there.

[Shiloh]

someone here recomended the cleaner Comet for cleaning=deburring moulds. I have tried it and it works well for me.

Me too.
It's what I now use.

Shiloh

[Fishman]

What about JB borepaste?

[GLL]

I used to live near Trona when I worked at China Lake. The place is a dump.

Calling the town of Trona a "dump" is being very generous ! It is perhaps the VERY worst town in the entire southwest ! I travel through three times a year and never even slow down ! :) :)

The mineral trona is hydrated sodium bicarbonate with a Mohs hardness=3. I cannot see how it or baking soda (sodium bicarbonate) can possibly be used to lap an iron mold ! Way too soft !

Jerry ("Geology Geek")

[montana_charlie]

The mineral trona is hydrated sodium bicarbonate with a Mohs hardness=3. I cannot see how it or baking soda (sodium bicarbonate) can possibly be used to lap an iron mold ! Way too soft !
What would you say about feldspar?

CM

[Freightman]

A drive through Trona
http://www.youtube.com/watch?v=ZV2mh38l3cg

[GLL]

CM:

All of the various feldspars have a Mohs Hardness = 6. Iron varies from 4-5.

Jerry

[GLL]

Freightman:

The Trona video is great. Please note that they drove through the upscale "high rent district" ! :)

I take my students out onto the dry lake each year to collect mineral samples. The town is pretty bad but the people are very nice !

Jerry

[pdawg_shooter]

I use a bar of white polishing compound I got from a jeweler. Shave a little off and mix it with light oil. Leaves the cavity looking like it is chrome plated.

[GLL]

pdawg:

The white compound may be tin oxide. I use both tin oxide and cerium oxide to polish cavities.

Jerry

[pdawg_shooter]

Dont know, but it sure works good. Dont know the grit number but is is way finer feeling than some 1200 grit lapping compound I have on hand.