Fresco technique are classical drawings made by using oxides straight on walls before surfaces are dry (the surface is covered with a mixture of lime and pure sand then drawings are made quickly in a very short period of time before it dries). The advantage of this material is its capacity of adhering to the surface, its strength and fast colors. It was used by the ancient Copt artist on church and convent walls and the colors are still there. Because of the frescoes mixture's (lime and sand) strength , it was used to fix stones during the 1999 restoration works on the Sphinx.
In spite of its originality, it is used by very few artists as it needs great skill, rapidity and the ability to work the raw material to reach the required results. This material is very suitable for churches as the colors are stable and the materials natural.