Author Topic: baking (Read 3281 times)

Raymond · « **on:** October 25, 2006, 12:47:43 pm »

Is it essential to bake the coins after cleaning? I understand the importance of ensuring that moisture does not adhere to the coin. Will repeated cycles of cleaning/baking help to gently remove crud on the coins? Can the baking cause the ridges formed by the letters to become brittle so that when I pass over with my heavy duty bronze bristle brush, I effectively tear off the identification of the coin?
It seems that many of my uncleaned show more detail before my attempts to clean.
Raymond

areich · « **Reply #1 on:** October 25, 2006, 04:38:49 pm »

I had the exact same thing when I started with uncleaneds. There is a type of patina (kind of blue-green in colour) that flakes off under a toothbrush. I had a lot of coins where I scrubbed all the detail away.

peterpil19 · « **Reply #2 on:** October 26, 2006, 05:39:18 am »

Hi,

I don't think baking is essential, I've never done it myself and haven't had much in the way of BD problems for coins I've cleaned and waxed. After cleaning, I usually dry the coins using a hair-dryer though I'm sure there are more efficient methods.

Baking is certainly not intended to be part of the cleaning process, but rather the conservation process. If you haven't finished cleaning, don't bake, just store in the olive oil or distilled water.

Incidentally, be careful with your bronze bristle brush. Unless your coin is covered in layers of crud, it is probably overkill.

Peter

Raymond · « **Reply #3 on:** October 26, 2006, 09:56:14 am »

Bronze bristle Overkill! Ha, I think many of my uncleaned have been massacred at the cleansing altar. So far, I have managed to limit the damage, I think, to the more common late bronzes. I have experimented with electrolysis, various solvents including Coca Cola, distilled water and olive oil. The only conclusion that I have come up with is that the best method to clean depends on the condition and the material of the coin itself. What I fear is that someday, I may come across a fourré and in seconds rip its coating off!
Raymond

Arnulf · « **Reply #4 on:** November 18, 2006, 12:25:30 pm »

Hi rapre...

I don't bake either. Seems to me (and I'm not saying this is scientifically correct...it's only my opinion), that since the relatively extreme heat of an oven will cause the metal to expand slightly and subsequent cooling will cause it to contract, fragile metal matrices and patinas could become weaker than they may already be. I just leave my cleaned coins out on a cotton napkin for a few days before I wax them. It won't make them utterly dry...only as dry as the humidity in the air allows...but it makes them dry enough in an environment to which they're accustomed.

Though I've only been collecting for two years, I can say that the oldest members of my collection are no worse for wear with just air drying and though I've cleaned many coins with BD, none of mine have developed it on their own.

Hope this helps,
Chris

Raymond · « **Reply #5 on:** November 21, 2006, 04:31:30 pm »

Waxing?! I was just wondering about that. With the central heating going full blast now, the air dries anything very quickly. I noticed tha some of my "cleaned" coins appear to lose definition as they dry. In particular, one worn prutah shows a nice umbrella pattern when moistened with oil which fades after a a couple of weeks. Some of my Romans have an almost pea green patina that seems to grey or get dull over time. Is waxing the answer?

areich · « **Reply #6 on:** November 21, 2006, 04:34:18 pm »

Waxing will do the same as moistening them but I stopped doing that because I hate the feel of waxed coins.

Scotvs Capitis · « **Reply #7 on:** November 21, 2006, 09:19:49 pm »

I love a waxed coin, it has a slick feel and feels in the hand like it is safe and secure (it isn't, but it is partially protected and must be checked periodicaly as do all coins, waxed or not.)

I also like the shine a buffed waxed coin has, looks as good as a wet coin and keeps the depth of color in the chalky/porous patinas that sometimes occur.

moonmoth · « **Reply #8 on:** November 22, 2006, 12:04:30 am »

Well, there are other views! I think some coins are ruined by being waxed. A waxed coin loses permanently the matt finish that some coins have. Also, it makes them almost impossible to photograph properly - they are nothing but a mass of shiny glints and highlights! And to me, it's important to be able to get a good photo.

If you like the waxed effect, though, you might also consider using a silver brush. These add a subtle gleam to coins. People say this is a cleaning effect, but I suspect these brushes also add a tiny amount of silver to the surface. (I don't use these either, but I have tried one out.)

Scotvs Capitis · « **Reply #9 on:** November 22, 2006, 01:10:27 am »

Photography of a waxed coin is indeed tricky unless you use a diffuser on your light. Even then it can get tricky. If they are nice coins, I scan or photograph my waxed coins BEFORE I buff them. Something about a nice buffed coin though...

You are correct to say some coins do not benefit from waxing. There are certain patinas that are not going to improve with waxing at all. For the so-called desert patina, for example, waxing is a big mistake. Perhaps I should have been more precise.

moonmoth · « **Reply #10 on:** November 22, 2006, 01:47:59 am »

Ah yes, I certainly wouldn't advocate waxing a sandy coin! And there are other obvious no-wax coins too, which have very rough surfaces like the first one below, a billon tetradrachm of the Sasanid Ardashir I.

But I was really thinking of coins like the second one, an as of Augustus. It's quite shiny enough for me already.

Scotvs Capitis · « **Reply #11 on:** November 22, 2006, 02:23:43 am »

Both of those nice coins would be glitter in the lens if waxed and buffed. Good example, thanks!

Raymond · « **Reply #12 on:** November 22, 2006, 11:47:21 am »

For example, I have a coin that's been soaking in oil for over a month now. I believe that its doesn't have much potential since both sides show no texture whatsoever. Nevertheless, the obv is readily distinguishable as a black silhouette (probably C. II) on a yellowish marbled background and the rev shows the emperor's silhouette standing left in what is most likely FEL TEMP REPARATIO, again all forms are surrounded within a marbled yellowish background. A drop of oil or water brings out a crisper detail on the coin which fades after a half hour.
Same thing with another coin: it's a pale green chipped disk with no discernible features. Add a drop of oil or water and it turns malachite green, the emperor in veil appears and on the rev., a winged Victory (I think). Oil has a more dramatic and longer lasting effect than water.
How can I keep the features visible for more than a few minutes? Wax?
Raymond

Arnulf · « **Reply #13 on:** November 22, 2006, 10:50:34 pm »

I think you'll find a wide difference of opinions on waxing...even if you find someone who advocates it, some people appreciate different types of wax. Personally, I have had no problem scanning my waxed bronzes (see the Severan Provincial attached...it has been both waxed with Ren Wax and buffed prior to the scan). While waxing is not 100% protection for your coins, it does do well protecting your coins from moisture, oil from your skin, etc., though as Scotvs says, it's a good idea to check for BD and other environmental damage on all your coins every so often.

Moonmoth...nice coins with a great look even without the wax...though what's that light-blue dot at 3 o'clock on the Sassanid obverse?

Chris

moonmoth · « **Reply #14 on:** November 23, 2006, 04:02:51 am »

Quote from: Arnulf on November 22, 2006, 10:50:34 pm

Moonmoth...nice coins with a great look even without the wax...though what's that light-blue dot at 3 o'clock on the Sassanid obverse?
Chris

Well spotted! In fact there are a lot of tiny greenish-blue spots on this coin, but they seem to be stable and to have a smooth surface. You might be able to see that on this close-up. But even so, I am keeping an eye on them!

Raymond · « **Reply #15 on:** November 23, 2006, 01:45:53 pm »

I'm impressed that Chris posted that provincial! It just so happens that I was staring at one just like it a few minutes ago, going through WildWinds under Phillip I and II looking to ID it. Not much lettering on mine though but the protrait on it seems rounder than the one posted below, an obstinate looking face.

Raymond · « **Reply #16 on:** November 24, 2006, 09:42:35 am »

I notice also that after cleaning (and baking), most likely before waxing, some members apply a colouring agent to "restore" the patina of a coin, either green or brown. Would this effectively remove the marks of overzealous brass brushing which exposes the metal on the high points of a coin?
Raymond

Scotvs Capitis · « **Reply #17 on:** November 24, 2006, 10:12:08 am »

rapre,

This is a can of worms.

Using a false patina agent is considered heresy by some, and a godsend by others. The truth is that is you look at a large what is sold out there on coin sites, much of it has a false patina. It is fairly easy to spot if you know what to look for.

The answer is clean coins more carefully

but in the end there are always coins that get stripped to some degree, or coins that had no other hope of being cleaned but to be subjected to harsh methods. For these, some people advocate 'repatination'. There are a number of methods, most are chemical or electrical treatments, some use simple products you buy, some are pretty complicated processes involving heat and chemical solutions mixed by the individual. There are ways to apply a false patina by electrical means as well. Many of these are quite convincing.

The ethical debate rages here off and on, but generally you find that more people make use of false patina than talk about it. My advice is if you DO use these methods, note it on your attribution card so that future generations will know the nature of the coin.

Personally, I am not against the practice, but I always qualify that by saying I try to preserve the original patina as much as possible, and can like with a few high points brushed bare on a coin. Its the crusty, nasty, hopeless coins that get harsh cleaning methods that I will re-patinate. These are coins that no one would ever appreciate in their uncleaned state and have no value to collecting as crispy lumps of metallic corrosion, and would never be appreciated were it not for harsher cleaning methods.

As you can probably gather, harsh cleaning and repatination are touchy subjects. Some purists SEEM to prefer a coin remain a corroded lump of cupric mineralization than be cleaned by electrolysis and re-toned. I exaggerate of course, but sometimes one who does these things can be made to feel like a heretic by holier-than-thou types among us.

Just use some discernment and common sense. If it can be cleaned properly with a little patience, go for it and apply the most important skill to cleaning - patience. If after all else fails, then it is time to consider harsh methods.

Raymond · « **Reply #18 on:** November 29, 2006, 03:13:37 pm »

Here's another "bright" question: what do you use to hold the coin if you want to attack a bit of encrustation with a bamboo pick or (heaven forbid) the dental pick? A flyfishing clamp?
Some "uncleaned" look fine to me, particularly those with the coloured patina of a desert. I'm afraid that scraping it down will make the colouration disappear and with that the details..
Raymond

Arnulf · « **Reply #19 on:** November 29, 2006, 04:05:26 pm »

Hi Raymond...

I use...::drumroll::...my fingers.

Holding the coin in one hand while gently scraping off encrustations lets you feel just how much pressure you're applying. You can also just hold it down on a soft cloth. I don't use anything fancy (just a table magnifying lamp or a magnifying head set), but those who use microscopes will have other suggestions.

Scraping down the desert patina will make the pretty color disappear...and you won't have anything half-as-good underneath. The cool thing about the desert patina or other similar kinds is that the brightness of the patina in the fields really brings out the details of the devices...and on an AE3 or AE4 it can be a beautiful effect.

Chris

Scotvs Capitis · « **Reply #20 on:** December 03, 2006, 01:00:40 am »

Quote from: rapre on November 29, 2006, 03:13:37 pm

Here's another "bright" question: what do you use to hold the coin

I use my fingers too. Its the best way to be "in touch" (sorry

) with your work.

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Author Topic: baking (Read 3281 times)

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Arnulf

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