Wednesday, July 24, 2019
George handed me a 2 x 2 inch cardboard coin holder and, with tears in his eyes, said: "Can you mend this for me?" I looked, in horror, at what appeared to be the shattered remains of a coin as George explained that it was once an Iron Age silver unit that he had been carrying around in his pocket to proudly show his friends.
Cardboard coin holders fold over the coin and retain it in a circular Mylar plastic window, created by sticking or stapling the two card halves together, they are then usually stored in an appropriately sized coin filing or storage box. The holders are perfectly adequate for protecting robust modern coins under most circumstances, but they are too flimsy to protect fragile and brittle older coins other than in a rigid container with suitable packing to stop the coin holder moving around. Personally, I prefer the rigid plastic coin capsules for transporting old coins; even then, unless the coin fits snugly, I like to pack the coin within the capsule with jiffy foam or acid-free tissue.
If you need to join parts of coins or artefacts together in the way of a repair, ideally the join should be reversible so that it can be dismantled if there is an error or for some other reason. Similarly coatings (lacquer) may need to be removed to deal with internal corrosion. Paraloid B72 is a glass-clear, non-yellowing soluble plastic, highly recommended by conservationists for joining and lacquering metals. Joins can be easily taken apart and coatings removed by brushing Acetone over the object with a fine brush. Made-up adhesive and lacquer are available from conservation material suppliers. However, the product contains a flammable solvent, which Royal Mail and most other postal services won't carry, so transport costs are very high. Nevertheless I have devised a cunning plan to get around this. Paraloid B72 itself is available as solid plastic beads, which can be sent by post and the solvent, Acetone, can be sourced locally, so you can easily and quickly make your own adhesive and lacquer.
I am offering small bags of Paraloid B72 beads for dissolving in 50ml Acetone on Ebay as follows:
5gm makes 10% lacquer
10gm makes 20% lacquer
25gm makes 50% adhesive
25gm + 5gm makes 50ml each lacquer and adhesive.
I recommend buying the Care+ brand 50ml Acetone bottles available at many local chemists and online from suppliers with transport arrangements.
If you buy Acetone in a small bottle like this you can safely make-up and store your adhesive or lacquer in the same bottle. If you buy larger quantities of pure Acetone - you don't want it coloured or perfumed as is often the case with nail polish remover -then it will be best to find small sealable glass bottles to use for adhesive and lacquer as Acetone will dissolve its way through some plastic bottles (HDPE, High Density Polyethylene is Acetone resistant). Acetone is used in glass reinforced plastic (fibreglass) construction and repair, so you will also find it at auto parts shops and yacht chandlers in larger quantities.
To make our adhesive we need to dissolve 25gm Paraloid B72 beads in 50ml Acetone to make a 50% solution; and dissolve 5-10gm Paraloid B72 beads in 50ml Acetone to make a 10-20% solution of lacquer (I prefer 10%). Using the 50ml or similar bottles of Acetone, you can just pop a few beads at a time into the appropriate bottle, wearing surgical gloves or using tweezers (as the plastic beads may irritate the skin), until the liquid reaches the top, screw the top on and shake or leave to stand until dissolved. Repeat until the appropriate quantity of beads are in solution, label the bottle and that is all there is to it. To make a repair, ideally, you will need three bottles, one each of adhesive, lacquer and pure Acetone.
The first thing I needed to do with George's coin was to lay the pieces out on a solid surface and fit it all together dry, with the design and breaks all matching up. I needed to work under a hands-free magnifier for this tiny coin and also had to use tweezers to handle the very small pieces. When I had the pieces together, I noticed there was a piece missing out of the edge. I discussed this with George, who said that the coin was like that when he found it and yes, he would like me to fill in the gap.
I use a machine vice to hold small objects steady while I work on them. The jaws of these vices are too deep to just put in slim objects like coins, so I use thin pieces of wood or Lego bricks, narrower than the object I am holding, to make a platform near the top of the jaws. When I am using adhesive or lacquer I put Silicone release paper (the backing paper for self-adhesive labels and the like) on the top surface of the platform, held in place by a couple of pieces of sticky tape, so that, at worst, the object being glued only sticks to the paper, which can be peeled off easily.
Starting with the largest coin fragment, I put this in the vice, making sure the edge to be joined was accessible and unobstructed. The vice has to be tightened very gently, and I mean "touch of a butterfly's wing" gently, otherwise the object you are trying to hold steady could bend, buckle or shatter. Once the main fragment was held, I placed the next fragment to be joined on alongside, with a small gap in between the two pieces. I then applied the adhesive generously with a cocktail stick to the broken edge of the main fragment, and pushed the smaller fragment firmly into place with tweezers and held it there for about a minute. The adhesive oozes out of the join but that isn't a problem as it will be dealt with later. After about 15 minutes the adhesive had dried, so the coin could be carefully repositioned in the vice to expose the next edge to be joined and the gluing process repeated and so on, until all the fragments were reunited.
George's coin had a roughly triangular piece missing, which needed filling to make the repair stronger and at the same time improve the coin's appearance. Bearing in mind that repairs may need to be undone and fillers are not easy to remove, before any filling takes place a liberal coating of Paraloid B72 lacquer should be applied to the edges of the section and immediate surrounds so that the filler sticks to the lacquer and not to the coin itself. If it is necessary to undo the repair, the lacquer can be dissolved with Acetone and the filler will fall out.
A suitable filler is a two-part polyester resin, such as Plastic Padding or David's Isopon, originally formulated for car and boat body repairs but now used around the home too and readily available from hardware stores as well as auto parts shops and yacht chandlers. The package contains two tubes, one of resin and the other of catalyst or hardener. To use the filler you squeeze out equal lengths of "paste" from the two tubes onto a scrap piece of say, plastic or cardboard; mix the two together thoroughly and use within five minutes before the mixture sets rock-hard.
I placed the coin on a piece of Silicone release paper and had a cocktail stick and scalpel to hand. Using the cocktail stick I mixed the hardener with the resin and transferred the mixture into the gap, roughly shaping the filler to the profile of the coin. Just as the filler was going hard, I trimmed the uneven edge with the scalpel then left it to harden. It is important to get the repair as good as possible before the filler hardens as in this application; realistically, you are not going to be able to make any changes! To hard filler and you would have to dissolve out failures and start again. I could have attempted to carve missing features into the filler but since we can only guess what might have been there, I just left the filler with a rough surface to blend in. To finish off, I gave the hard filler a coating of silver Humbrol model paint. The final job was to coat the complete coin in Paraloid B72 lacquer, which fills any small cavities and effectively encapsulates the entire coin in a plastic film, holding it more firmly together. As the lacquer can soften the adhesive to the extent that the joins come apart, lacquering is best carried out back in the vice. With so many joins in George's coin I couldn't clamp across all of them so with the reverse side up, where the join lines were more prominent, I positioned the coin so that I could hold two main joins together and just watched that nothing came adrift elsewhere. Using a clean small artist's paint brush I coated the reverse of the coin with lacquer then looked for any solid lumps formed or left behind from the gluing process. As there were a few lumps, I brushed them out with acetone and they disappeared into the lacquer coating. Once the lacquer was dry, I turned the coin over in the vice and lacquered the obverse in the same manner. When that was dry I took the coin out of the vice, held it between finger and thumb, lacquered the edge and allowed it to dry. The repaired coin was now easy to identify in Ancient British Coins, as an Iceni, Bury diadem silver unit, which, because of its protective coat, could now be handled with reasonable care and displayed with impunity.
At the next club meeting, I handed the coin, in a coin capsule, back to George without comment to which George said: “That’s nice, where did you find it?" I quipped something about finding it locally and left George to look at his coin. Ten minutes later George came back to me and said: “That’s my coin isn't it? It looks better than when I found it."
Friday, April 19, 2019
The Penrith Hoard in the British Museum Copyright 2010 Ealdgyth and reused under a Creative Commons Attribution-Share Alike 3.0 Unported license
“There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy.” Hamlet 1:5
I would imagine that all detectorists have an interest in improving the quality and quantity of their finds. Yet very few make use of a free technology that can bring spectacular results when employed alongside a metal detector. Dowsing probably hasn't caught on with detectorists because of common beliefs that either it doesn't work or it is impractical. My own experiences, however, have convinced me that dowsing does work and that it can be very easily put to practical use.
Many years ago, having long had a casual interest in the so-called paranormal, I decided to give dowsing a try and bought a pair of L-rods. The instructions claimed that it was necessary to rest one end of each rod in the palm of each hand while supporting the rod loosely between the thumb and forefinger. I found this terribly uncomfortable; couldn't get them to work and didn't have a clue what to do with them if I did get them to work. I gave up on the idea of being able to dowse myself, and discarded the rods. There were two important points that I later learned from this experience:
1. I had unwittingly fallen foul of one of the basic rules of dowsing - you need to be relaxed and comfortable with what you are doing.
2. The fact that nobody really knows how dowsing works, tends to attract those with fanciful ideas on how you should or shouldn't dowse; there are no strict rules, you just dowse as you want.
Sometime later, I asked accomplished dowser Jimmy Longton to dowse a map for me. (See post: To the Manor Drawn, February 22 2015). In addition to dowsing the map, Jimmy tried very hard to encourage me to learn his craft. I was still very sceptical, even though the British Society of Dowsers claim that: "Most of us can develop the art by practice and perseverance". When Jimmy told me of his find of a hoard of Viking silver brooches, I could see the improvements that dowsing might bring to my own finds. There appeared to be a more convincing alternative, however, the Long Range Locator. I bought an Electroscope and learned to use it with good results.
About a year later, following a discussion on dowsing, my mother-in-law announced that she would like a pair of dowsing rods for her birthday. I thought she deserved a little more than two remodelled coat hangers so I splashed out on a pair of commercial rods. On her birthday she handed me the rods and asked me to show her how to use them. "They don't work for me" I explained, "But this is what you are supposed to do ..." With that, I threw a pound coin on the lawn in front of me and proceeded to walk towards it, rods in dowsing mode. To my surprise the rods crossed as I walked over the coin. Intrigued by my new-found ability, I experimented with L-rods and discovered that they responded to buried metal in much the same way as the Electroscope. I can only conclude that by using the Electroscope I had actually taught myself to dowse.
There is no need to spend several hundreds of pounds just to learn to dowse. Jimmy Longton kindly allowed me to reproduce his rod design and dowsing work-out, so you can learn for nothing! If you already have a pair of L-rods, you can use them, if you like, or you can make excellent rods as follows:
You will need 22 in. (56 cm) of round metal bar (brass is considered best) of diameter 1/16 in. (1.5 mm) to 3/16 in. (5mm) to make each rod. Unless you have easy access to round bar, I suggest you use two wire coat hangers (N.B. Measurements and angles do not need to be too precise to make a working rod):
1. Invert the first hanger and measure 14 in. (36 cm.) from one side, along the horizontal bar then mark and cut through with a pair of pliers or a junior hacksaw, measure 22 in. (56 cm.) back from the first cut and make a second cut. Discard the hooked portion. (Fig. 1).
2. Smooth the cut ends with a file or emery cloth.
3. Using a pair of pliers or a vice, first straighten and then bend the shorter arm back to an angle of 135 degrees (Fig. 2).
4. Measure 7 in. (18 cm.) along the shorter arm, from its end and bend this portion back until horizontal (Fig. 3), then turn the last 5.5 in. (14 cm.) up at right angles. Finally, turn the last 0.5 in. (1 cm.) of the upright inwards, at right angles (fig 4.).
5. Lay the rod on a level surface and adjust it until it lies reasonably flat.
6. Make a second rod from the other coat hanger.
Health warning: The rods are perfectly harmless when used as described. If you wish to use them to play Conan the Barbarian, Robin Hood, Ivanhoe or act out any other fantasy, don't blame me if you puncture your eyeball or any other part of your body. I would suggest that children using the rods should be supervised by a responsible adult. The rods can be made extra safe by folding their tips back on themselves, wrapping their tips with insulating tape or applying a blob of resin such as Araldite.
Take the short arm of a rod in each hand so that the long arm is on the opposite side to your thumbs. Clench your fists around them loosely and turn your wrists so that your thumbs are uppermost. Tuck your elbows into your body and keep your upper arms in line with your body. Hold your forearms straight out in front of you, the width of your body apart and at whatever angle necessary to keep the rods reasonably parallel to the ground. The rods should now be pointing forward like extensions of your forearms. You may need to adjust your grip so that the rods are just free to move but not sloppy. When you are happy with holding the rods we can move on to the exercises:
1. Hold the rods in the normal dowsing position as just described. Ask the rods to turn left. (You have to treat them like pets; talk to them nicely at first but if they don't do as they are told, shout at them - it works, honest!) After they have moved, restart the rods pointing forward. The easy way to get the rods to point forward is to drop your forearms so that the rods point to the ground then raise your forearms back to the horizontal. Ask the rods to turn right. Restart. Ask the rods to cross. The rods will cross on your chest. Practice until the rods move easily.
2. Place a coin on the floor then take a few paces back from it. Hold your rods in the normal dowsing position and walk slowly toward the coin saying, (out loud, preferably): "I am looking for a coin". The rods will either cross as you pass immediately over the coin or within a few paces past the coin. Keep practising until the rods cross at the coin.
3. Place a copper coin, a silver coin and a brass coin some distance apart on the ground. Hold your rods in the normal dowsing position and walk slowly toward the coin saying: "I am looking for a copper coin". The rods will cross as you pass over the copper coin but not the other two. Repeat the exercise with the silver coin and then the brass. Keep practising until you can differentiate between various metals.
4. Stand sideways to a distant building or other large object that you know the location of and ask the rods to show you where it is. Give the full name of the place, i.e. "Show me St. James' Church". Clear you mind of everything else and concentrate. Once you get this to work, try standing with your back to the "target" (as dowsers tend to call objects they are trying to find) and see what happens.
5. When you have succeeded with exercise 4, take your rods to the gate of a field, which is available to you for searching. Hold the rods as normal and ask: "are there any coins buried in this field?" The rods will cross if there are. Ask the rods to point to the nearest coin, then walk slowly in the direction indicated by the rods, turning, as necessary, to keep the rods pointing straight out in front of you. On reaching the coin the rods will cross. If you want to search for other objects as well as coins, ask the rods to find treasure.
Keep practising. Once you can obtain a response from the rods in all these exercises, you are basically ready to do anything. Even if you can't do it all at first, you should find that the rods will produce some useful results in the field and you will improve with time.
You may have noticed that in exercise 5 you reached your first buried coin but how do you recover it, bearing in mind that you have no hands free to carry anything? Hopefully you will have brought someone else along who can, at least, carry your metal detector and extraction tool, if not do the detecting and digging for you. If you are the independent sort, you don't need to have a partner, it's very easy to both dowse and recover targets by yourself. I'll show you how next time.
First Published in The Searcher/ November 1997
Wednesday, April 10, 2019
Following on from a previous blog, I am pleased to report that the repair I carried out on my Garrett Pro-pointer has worked and the probe is back in service. There are some YouTube videos which show you how to fix the fairly common falsing problem, which is caused by some bare wires shorting out. So if your probe starts falsing, just search on YouTube for ‘Garrett Pro-pointer repair’.
I picked up this Gold Hunter electronic pinpoint probe as a giveaway when I bought a new Detech Gold Catcher metal detector. It came with pouch and lanyard and you can buy them new, shopping around, for £30 or so, which is good value for money. As my Garrett Pro-pointer was playing up at the time, I put it to use and found it very good on inland sites. Both the sound level and sensitivity are good and the second button allows you to have vibration alone or sound and vibration. It is slightly slower switching on and off than the Garrett, which you may not think is important but the faster you can get your find out of the ground, the more finds you will make. The only real downside I found with this pointer was on the wet beach where it falses so much I found it unusable. But if you are only detecting inland sites and dry beaches, then this probe is great value for money.
Search for pinpointers on Ebay: (affiliate link)
Saturday, March 30, 2019
Revising the definition of treasure in the Treasure Act 1996 and revising the related codes of practice
Hoard of Iron Age gold Staters
The UK Government Department for Digital, Culture, Media and Sport, which is ultimately responsible for the Treasure Act and Code of Practice, has produced a consultation document outlining proposed changes. While much of the proposals are little more than housekeeping there are some material changes that are of some concern.
At present, treasure is defined, under the Act, as any object other than a coin, at least 300 years old when found, which has a metallic content, of which at least 10% by weight is gold or silver. And all coins that contain at least 10% by weight of gold or silver that come from the same find consisting of at least two coins, at least 300 years old. And all coins that contain less than 10% by weight gold or silver that come from the same find consisting of at least ten coins at least 300 years old. And any associated objects (e.g. a pot or other container), except unworked natural objects, found in the same place as treasure objects. And any objects or coin hoards less than 300 years old, made substantially of gold and silver that have been deliberately hidden with the intention of recovery and for which the owner is unknown. From 1 January 2003 the definition of treasure was extended on prehistoric (i.e. up to the end of the Iron Age) finds to include all multiple artifacts, made of any metal, found together and single artifacts deliberately containing any quantity of precious metal.
It is now proposed to add:
· Any found object over 200 years old with a value over £10,000
· All single gold coins dated between 43 and 1344
· Two or more base metal objects of Roman date believed to have been intentionally buried together
There is also a proposal to impose a legal duty on the acquirer of a possible treasure find to report it and to impose a presumption that acquired treasure finds were found after the Treasure Act. This is fraught with difficulties. Under the Treasure Act rewards are split equally between finder and landowner (unless there is a different agreement in place) so will private acquirers report potential treasure if they stand to lose half its value if it is declared treasure? Potential treasure items were being found for 25 years before the Treasure Act, so assuming half of today’s find rate, that amounts to some 12,000 exempt treasures somewhere, many probably in inherited collections. The presumption of found since the Treasure Act seems contrary to English Law – innocent until proven guilty. Does the acquirer take the seller’s word for when the item was found? It is often impossible to PROVE when and where an item was found. Surely it is up to the State to prove it was found after the Treasure Act. The findspot is held up to be vitally important but in these cases, it is likely to be erroneous or completely lacking, so what is the point?
Wednesday, November 28, 2018
An extremely useful metal detecting accessory is an electronic pinpoint probe; a hand-held miniature metal detector, identifying all metal by audio and vibrating. This gadget helps identify the exact position of the find in and out of the ground so you can not only avoid damaging your find but speed up find extraction considerably. Probes have other uses too. You can check the surface for shallow finds before you dig, which is especially useful when searching sensitive areas like lawns or when searching for a recent loss – you usually only need to check the shallow signals. Probes with a limited range, perhaps no more than an inch on a coin-sized object, have been around for a long time but a few years back Garrett brought out the Pro-Pointer which has a greater range and a larger price tag but is so much better at pinpointing than the old style probes. I bought a Garrett Pro-pointer when they were first available in the
and have had 10 years of reliable service out of it but recently it started
sounding-off (falsing) for no apparent reason, even with a new battery, which made
me think it had come to the end of its working life. I had a look around to see what was available
and it seems almost every metal detector manufacturer now makes these probes in
many colors. But the cost of some of them is bordering on the ridiculous – you
could easily buy a good, brand new, entry level metal detector for the price!
There are quite a few tests on YouTube and one thing that struck me was that
the Chinese had got in on the act and they have a probe available at less than
twenty pounds or twenty-five dollars, which includes holster, lanyard and
shipping! The model in question is called a GP-Pointer and it tested quite well
on YouTube so I thought I would give it a try. It is almost identical to the
Garrett in appearance. Switching on takes about 3 seconds; whereas Garrett is
instant. The GP is not quite as sensitive, nor as loud, nor vibrates so
strongly as the Garrett. I didn’t find any of this to be a problem even when
wearing headphones but I do have good hearing and did not need to wear thick
gloves at the time. It may be difficult to use in a noisy environment and by
anyone with poor hearing but for its price, I found it a great tool for the
As a footnote, I did a Google search for ‘repair Garrett Pro-pointer’ and found some YouTube videos which show you how to fix the fairly common falsing problem. I have taken the advice and had a go at repairing mine. So far so good, it still works but I have yet to field test it.
Tuesday, November 20, 2018
In TheSuccessful Treasure Hunter’s Secret Manual, I looked at thermal and electrical conductivity as a possible explanation as to why some metals produce stronger auras than others. What I discovered through experimentation is that different metals produce different auras and fortunately precious metals produce the strongest auras. In other words a smaller amount of gold or silver will produce an aura than is the case with base metals. This stuff is so cutting edge that I’m afraid I don’t know all the answers. I do recall that when I was doing a lot of beach treasure hunting in the summer evenings, when the crowds had left, that coins coming out of the sand were always quite hot to the touch. The mechanism is presumably emission of infrared radiation selectively absorbed by metals from the sun although it could just as likely be metallic interference with the earth’s magnetic field. It doesn’t matter too much, as it is results in finds that we’re after, not a degree in physics. A useful way of comparing metals seems to be thermal and electrical conductivity, I must stress these may not be the only factors or even the correct factors that determine aura strength but they do tie in quite nicely with my observations.
Silver has a thermal conductivity of 420 Watts per metre-Kelvin and an electrical conductivity of 62,000,000 Siemens per metre. Pure copper has a thermal conductivity of 370 W/mk and an electrical conductivity of 59,500,000 S/m. Gold has a thermal conductivity of 315 W/mk and an electrical conductivity of 45,000,000 S/m. Pure copper has conductivities in between gold and silver, however copper is normally found alloyed with zinc or tin forming brass or bronze respectively, which have much lower conductivities, typically a thermal conductivity of 125 W/mk and an electrical conductivity of 15,000,000 S/m. Soil, sand and water have thermal and electrical conductivities around 1 W/mk / S/m or less. Diamond, interestingly has the highest thermal conductivity of any known substance at 1000 W/mk but such an extremely low electrical conductivity it can be considered to be an insulator. Unfortunately I couldn’t afford a large heap of diamonds to test whether they produced auras but I said it might be something worth looking out for. I was sent the photo from a reliable source who claims it is a diamond aura. I must say it is a very unusual aura photo and I haven’t seen anything quite like it before. I would like to see a photo of the diamonds though, which might be available in due course.