When we Orthodox are Chrismated, we are stamped with the seal of the Holy Spirit. This usually happens immediately after our baptism. Chrismation causes us to become Christians - children of God and members of His body, the church.
When we prepare prosphoro, the bread dough is no different to that which we make for home consumption... until we crown the dough with the glorious stamp of the seal, which bears both a cross, and the initials of the victorious words "Jesus Christ - Victor". Once stamped with the seal, it is a prosphoro.
Everything we do in the preparation of our prosphoro is centered around the preservation of that impression, borne on a beautiful loaf made with love, care and prayer.
The most sought after seals are wooden, and hand-carved by monastics. We value the love and care with which these items are made. We cherish them and treat them with reverence since they serve a holy purpose.
When you look to purchase a wooden seal, try to find one that is hand made, with deep carvings, without cracks or splits or fine splinters among the motifs. Make sure it is round - some of them warp and become bent or oval in shape! Also, make sure that the very edge of the seal that contacts the dough is rounded and smooth. Too sharp an edge at the perimeter makes for circumferential tears on the prosphoro around the impression.
I have reversed the photo below to show the mirror image - the same as the impression on the dough. The central square is called the "Lamb". There are two more lambs one above and one below the central one. These are "spares" in case the main lamb is imperfect.
The large triangle on the left represents the Virgin Mary. On the right of the lamb, the nine small triangles commemorate the angels, prophets, apostles, holy fathers and prelates, martyrs, ascetics, holy unmercenaries, Joachim and Anna, and all the saints, including the saint honoured in that day's liturgy. The rest of the patterns and decorations are embellishments. Here is a link to a good video explanation of the proskomide service
Because the size of the prosphoro can differ (i.e. weight of dough/size of pan) we sometimes need different sized seals. They range from around 11 cms diameter to 19cms. It is very important to use a seal that is appropriate for the prosphoro / pan size you use. Too large a seal for the dough, and it is very difficult to stamp. Also, the edges of the impression get dragged down the sides and are lost during the rise. Too small a seal causes the rising dough to shrink the impression, sometimes to half its actual size!
There are seals with writing carved around the perimeter of the central motifs. They bear the words "Take, eat, this is My Body", or "Rejoice Mary, full of grace" (Used for services on feast days pertaining to the Theotokos)
When the services are small, with few people expected, the priests may request smaller prosphora. On feast days, heirarchical services or whenever larger numbers are expected, the priests may ask for prosphora with a larger central Lamb. (eg. the left and centre - bottom row).
Before buying a seal, it is best to check with your priest. He may have certain preferences. I was going to purchase a seal with a very large "Lamb". When my priest heard it he told me he'd have no use for prosphora stamped with such a seal, because the church had no chalice large enough to contain such a lamb.
TO OIL OR NOT TO OIL?
Many people advise that once you have bought your seal, you should strengthen it with a generous coat of olive or safflower oil. I've heard this advice from a monk as well as from some priests. You will notice in the image at the top of this blog, three seals are oiled. They are the more orange ones, top-centre, top-left and bottom-left.
Once you've coated a seal, and before you use it to stamp a prosphoro, it needs to be kept in paper towels a few weeks, so as to soak up the excess oil. They also recommend you perform a few stamps on bread dough to further remove excess oil.
What I've noticed (and others in the group have confirmed), is that after a while the oil becomes rancid and the seal smells bad! I've resorted to carefully using pure alcohol in small amounts with swabs to remove the oil and the odour from the stamps which I had oiled.
Mrs Eugenia, who has been preparing prosphora for decades says that if we're careful with the seals, it is not necessary to oil them at all. I am glad I have the three without oil. I wish I hadn't oiled the others. She advised only that I should be careful to not drop them! I recommend you do the same.
To protect them, I loosely wrap my seals in paper towels then aluminium foil and store them in a sturdy container. I have some bay leaves and basil leaves in the same container - it confers a lovely, subtle scent to them.
May God bless you on your prosphora baking journey!