Albs were sometimes worn plain, i.e., without apparel. The Salisbury Missal, for example, forbids the apparelled alb to be worn on Good Friday; and it is not at all impossible that some of the plain albs, as represented on early monuments, are really intended for unadorned vestments.
Some difference of opinion seems to exist among the authorities about the mystical signification of this vestment. Rabanus Maurus holds it to inculcate purity of life. Amalarius of Metz, contrasting Jerome's description of the tight-fitting Jewish tunic with the flowing alb of his own day, considers that it denotes the liberty of the New Testament dispensation as contrasted with the servitude of the Old. Pseudo-Alcuin thinks that it means perseverance in good deeds, and that therefore Joseph is described as wearing a tunica talaris among his brethren. 'For a tunic which reaches all the way to the ankles is a good work carried out to the end, for the ankle is the end of the body.' Ivo of Chartres asserts that it signifies the mortification and chastisement of the members. Honorius of Autun agrees more or less with Rabanus Maurus; but Innocent III regards it as symbolical of newness of life, 'because it is as unlike as possible to the garments of skins which are made from dead animals, and with which Adam was clothed after his fall.'
The following dimensions are among those given by Mrs Dolby as the correct measurements of an alb for a figure of medium height and ordinary proportions:
| ft. | in. | |
| Length behind when made | 4 | 9 |
| Length before | 4 | 5 |
| Depth of shoulder-band | 0 | 8½ |
| Width of same | 0 | 1¼ |
| Length of sleeve, outside of arm | 2 | 1½ |
| Width of sleeve at wrist folded in two | 0 | 6½ |
| Width of sleeve half-way up | 0 | 9½ |
| Length of neck-band | 2 | 2½ |
| Width of same | 0 | 1¼ |
| Opening down front | 1 | 1½ |
II. The Girdle, with which the alb is secured, is a narrow band, usually of silk, the ends of which terminate in a tassel.
The colour of the girdle is properly white, though occasionally it varied with the colour of the day. Though (as stated) properly of silk, it is sometimes made of cotton.
Occasionally the girdle was embroidered in colours. In the Westminster inventory of 1388 we have:
- 'Zone serice sunt septem diversi operis et diversorum colorum.'
The following is a selection of the esoteric meanings ascribed to this vestment: custodia mentis; discretio omnium virtutum; virtus continentiae; perfecta Christi caritas.
The length of the girdle is stated at about four yards. The length of the alb, it should be noticed, was so considerable that it was necessary to draw it through the girdle and let it hang over above it. It is therefore extremely rare (if not unknown) for the girdle to be visible on mediaeval monuments, for even in those exceptional effigies in which the whole length of the alb is visible, the latter vestment entirely conceals the girdle by falling over it.