Metal de-corroder and Pre-Lim

Have you ever used the product called Metal De-Corroder? It's made by same reputable company that makes Renaissance Wax. How about Pre-Lim? If you want to see my early work with both products, it can be seen on Instagram, my name is
"ancientcoinconserve." I once used the de-corroder with fantastic results. It completely separated this hard, BD-looking blue corrosion for a larger-sized bronze coin. Not much details were there to begin with, but I was quite impressed. I currently am leaving two new heavily corroded and encrusted coins in a diluted solution and will post the results soon. I'm interested in hearing your experience with this product. Also, Pre-Lim is a safe, subtle polishing cream. I use it here-and-there, it's subtle like I said. What's your experience with that product? Thanks for your time. Joe

 

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Interesting stuff, here is the MSDS, I would like to know how it works too.
http://www.kremer-pigmente.com/media/pdf/62902_SHD_ENG.pdf

 

It appears to just be an acid solution. The MSDS suggests by the pH and boiling point, it is just a weak acid ( pH4.0) and the density of 1.05 and Flash point of >93 degrees C. that most of the liquid is water. European products do not give as much details on MSDS forms as in US. Maybe there are other chemicals in it, but nothing very active or it would be listed.
http://www.kremer-pigmente.com/media/pdf/62902_SHD_ENG.pdf

Pre-Lim MSDS is also lacking in details. A Renaissance wax product that is "38% non-scratching abrasive" , but they do not give the material used so one can see the Moh Hardness number. Since they also recommend as a car-cleaner before waxing, I suspect they mean "no obvious scratching", so I can't find much. I use extremely fine grit when I facet gemstones and no scratches are visible to the naked eye or a 5x magnifier, but under a 30X, they are seen. Do a coin and send it to ICG or ANACS ( because they are less expensive and see if it gets detailed) Kentucky found the MSDS already

IMO,
Jim

 

Not sure if the citric acid would give some chelating ability...

 

I'm a lye man, myself. Quick and effective results. Just don't use it on any of your valuable coins, lest you lose the coin toss and ruin it

 

thanks for replying. Once i get done with soak, I’ll post pics. It’s been one day and I was surprised it hasn’t dissolved more of the crust like last time. It’ll probably take 1-2 days more, but it looks promising because at first solution was faintly blue, mostly cloudy white. Now it’s very blue. What is MSDS? And I’m unfamiliar with lye.

 

Can you elaborate a little more? What is it exactly? I thought I read before it’s dangerous so I never gave it much thought. The product I’m using said it’s non-toxic and gloves and breathing mask are not needed, just common sense. Always good to hear that

 

Lye is either sodium or potassium hydroxide. It is usually sold as household drain cleaner. In my neck of the woods, it was rather tough to find. I went to 2 Home Depot and 1 Ace Hardware in San Diego with no luck. Went to 2 Home Depot and 2 Ace Hardware in Irvine before I finally found a jar of the stuff for like 6 bucks.

I believe the stuff is generally frowned upon for drain cleaning these days; perhaps that's why it was tough to find.

It comes in crystal form. As dry crystals, there is no danger in handling with bare hands.

It is a very strong base and therefore very dangerous WHEN WET/in solution and can cause major burns and blindness. But just be safe and smart and you'll be fine.

Lye is basically the exact opposite of what you're using. Submerging copper-alloy metals into acid will often turn the water blue. If you use apple cider vinegar it turns the water green.

Using a base will only give the faintest blue color, and more generally leave a whitish residue in the water, if anything at all.

On metals like bronze and the like, both acids AND bases will have much the same effect - it will dissolve anything that isn't metal.

I used a product once called Gringgott's Wizard Mix #2, which was marketed as generally safe for use without protective equipment. I determined that it was some kind of milder base solution mix.

I have never tried using a comparably strong acid on coins, so I cannot speak to whether acids or bases are better suited for coin cleaning.

In my limited experience, I found that lye gave some decent results. I will post a thread tomorrow with some recent results, and I'll make sure to tag you in it.

 

I have seen what Lye can do, why use Lye, such strong stuff on an ancient coin as first remedy? It will make the coin porous as well as it will also thoroughly remove metal salts that are in the grain boundaries of the silver.
I use regularly lye to clean my R&D pilot reactors, that crap eats the glass coating away bit by bit and needs to be replaced every year.

 

An MSDS is a Material Safety Data Sheet and gives you information on stuff.

 

"It comes in crystal form. As dry crystals, there is no danger in handling with bare hands." NO NO NO NO NO, the "dry" crystals pick up water and are just a super concentrated form. Do not handle with bare hands, or wash soon after handling!!

I've used it before with what I consider were good results.

 

The fact that something dissolves glass is in no way to mean it is "strong".

 

In my experience, you often end up with a technicolor coin that needs a patina restoration and an application of wax.

if you're REALLY LUCKY you end up revealing a silver, or heavily silvered coin, in which case you're all set

 

In other words, it can certainly ruin your coins, but can also certainly make them better. Depends on how valuable the coin is currently, how valuable it COULD be if things go well, and how much value is lost if the coin fails.

 

Thanks for the correction. I'm not very safe with my chemicals :/

 

You and me both...even though I've only used cyanide once...

 

These are two complete seperate sentences. I never said Lye is strong because it eats away glass. It was an example what lye can do, even at very low concentrations. In general silicate glass is very resistant to chemicals, so the fact that lye can react with it tells you something as well, as far as I know, no mild chemicals can do it. You need to look at chemicals like hydrogen fluoride or boiled strong acids. And if we talk about chemistry, yes sodium hydroxide is considered 'strong', even if you know a little bit about chemistry, you would know what I mean.

Besides that lye can also react with other metals that can be present in the coin as trace element, you only make a coin porous.

 

I think Lye is strong because it has a pH of 13...

Even after neutralizing with LOTS of vinegar, and a long soak in distilled water, handling lye-treated coins often leave the skin of my fingers feeling a bit slimy, a characteristic of a mild base burn.

For my, and many average persons' usages, I think a strong acid or base can be considered anything that can cause burns if exposed to bare skin.

Fortunately I've never gotten injured by any chemical thus far, but it's still pretty dangerous to be around.

 

1) HF dissolved in water is hydrofluoric acid and is a weak acid 2) no other acid I know of would dissolve glass, boiling or not.

As an aside, as an undergraduate I was doing research that involved "dissolving" sodium hydroxide in methanol, 500 g of NaOH in 50.0 mL (yup 50) methanol. Had to add 500 ml of mineral oil to help and the reaction was run at about 200 degrees Celsius. After two reactions, I threw away the reaction vessel since the glass was eggshell thin from the NaOH!!!

 

HF acid is indeed a weak acid hence the use of "or" in my sentence. Besides that it is in able to act as a strong acid at higher concentrations since the bifluoride ions can form an extremely strong hydrogen bond with water. It reacts easily with glass to silicon tetrafluoride and hexafluorosilicic acid and is used a lot in the industry to etch glass. And yes strong acids such as HCl, H2SO4 and HNO3, can react with glass as well, but slower than NaOH, hence the boiling to increase reaction speed.