The Spirit Slates Magnetic talked about and demonstrated here are made by Bazar De Magia. There is also a Mak Magic Spirit Slates which is very similar in operation but the fine points in this article are about the Bazar De Magia prop.
Lets look at the positives of the Spirit Slates Magnetic . They can be handled freely after the effect, and even be inspected by members of the audience (I would not recommend this even in the close confines of a Seance). The Spirit Slates Magnetic are moderately priced around $90 and very well made. The effect is almost angle proof and could be done surrounded. These slates are also very quiet working when done properly. The magnetic slates in general are larger in size than most standard operating slates which makes them more visible and easier to see (One exception to this rule would be the Abbott's Spirit Slates Stage Size, which are the largest and most visible slates around, but also cost $200).
Couple of things I don't care for, I cannot fit a standard piece of chalk between the two slates when using the Spirit Slates Magnetic . That is why, in the demo, the piece of chalk is invisible but this is really just my preference. I like placing the chalk between the two slates and I am unable to fit it in this version. Handing out the Spirit Slates Magnetic may be asking for trouble because one slate will weigh significantly more than the other so if you do hand these out, hand one out to one group and another to another group, that way no one person will actually hold both slates and notice the weight difference (again, personally I would not hand these out, if one looked close enough at the slates they can see the gimmick). The gimmick sometimes does not line up properly, although this is easily corrected by sliding the slates apart rather than lifting them. If they are not lined up properly the sliding off of the top slate will correct it.
The Spirit Slates Magnetic are not as easy to handle as the standard slates and if you make a mistake in handling, it could cause the slates to "talk". Practice this effect, give it its due, and you should do fine with it. One problem some have is running out and trying these 5 minutes after getting them and that is a recipe for disaster.
With all spirit slates remember that they are primarily a revelation so you still have to have something to reveal (meaning Spirit Slates in general are only the finale or the end half of an effect).
A final note, the Bazar De Magia Spirit Slates Magnetic are considered to be the best slates on the market, they do make a non magnetic version as well but I have to say if you are going to go with the Bazar De Magia slates, get the magnetic ones (The reason for this is the standard version is $80 and the magnetic $91, only about a ten dollar difference).
In the demonstration I am using a glorpy to simulate the invisible writing and an Ipod to generate the sound. Remember to create a playlist for the chalk sound if you use an ipod and have the chalk sound the only sound in the playlist (this prevents other songs from playing once the chalk sound plays). The illusion is pretty strong with sound, visual action, and finally the effect!
These are terrific! In fact, we believe they are the finest set of magnetic locking slates you can see. The Spirit Slates have proven to be an extremely popular and versatile prop over the ages for stage performers, mentalists, and parlor prestidigitators.
These Spirit Slates give you a hands-free, no nonsense method of revealing mysterious writing. The flap lies perfectly flat and is invisible even under the most difficult of performing conditions. The Slates may even be handed out for close examination of the writing. They will see nothing suspicious. Nothing!
The performer presents two chalkboard slates and shows them blank on both sides. Placing a small piece of chalk between the wooden slates, he rubber bands them together. When the slates are reopened, the name of a selected card or writing on a burned billet has magically appeared on the slates. Spooooooky!
The slates themselves measure approximately 7" by 9 3/4" with beautiful mahogany wooden frames.
Manufactured of the highest caliber woods!
Special permanent paint!
Larger for a better view for larger audiences!
Perfect fitting flap mechanism.
Dimensions Approximately 11 3/4" x 9" (30cm x 23cm)
Comes complete with 2 Spirit Slates, chalk and instruction sheet.