Part the second: of colours or pigments

PART THE SECOND.
Chap. 35. Of the preparation of the colour.
In studying the arts progressively, we come next to the grinding of the colours. You must know that some colours are very fine, some coarse, and some impure ; that some require but little, others much grinding; that some demand one vehicle, some another ; that they differ in colour and in the manner of tempering and grinding them.
Chap. 36. What are natural colours (pigments), and how to grind black.
You must know that there are seven natural colours, namely, four which are of the nature of earths, as black, red, yellow, and green ; three are natural colours, but require the assistance of art, as white, ultramarine, or della magna, and Naples yellow. We will not proceed further, but return to the black pigment. To grind it properly, procure a slab of porphyry, which is strong and firm. There are many kinds of stone for grinding colours, as porphyry, serpentine, and marble. The serpentine is a soft stone, and is not good (1) ; marble is worse, that is, softer ; porphyry is the best of all ; and if you procure a slab very well polished, it will be better than one with less polish. It should be about half a braccio (2) square. Take another stone, also of porphyry, smooth on one side, and raised on the other, in the shape of a porringer, and half the height of one, of such a form that the hand may hold and guide it at pleasure (3). Then take some of the black (or of any other colour), about the size of a walnut, and put it on the slab, and with that stone which you hold in your hand break the pigment into small pieces. Put some clean water, either from a river, a fountain, or a well, to the colour, and grind it well for half an hour, or an hour, or as long as you please ; but know, that if you were to grind it for a year, so much the blacker and better would be the colour. Then take a fiat piece of wood, part of which is pared thin like the blade of a knife (4), and with this blade collect the colour neatly ; keep it liquid, and not too dry, that it may flow well on the stone, and be thoroughly ground ; then collect it carefully. Put it then into a small vase, and pour water on it till the vase is full ; and in this manner keep it always soft, and well covered from the dust, and from all other dirt, that is, in a little box adapted to hold vessels of liquor (5).
Chap. 37. How to make several kinds of black.
Remember that there are several black pigments, one of which is a soft black stone, and the colour is opaque. I must inform you that transparent colours are better than those which have much body, except that in laying on gold, bole, or verde terra, when you have pictures to gild, the richer the colour is, the brighter will be the gold. Let us leave this subject. Another black is made of the tendrils or young shoots of the vine (1), which are to be burnt, and when burnt, thrown into water, and quenched, and then ground like other black pigments. This colour is very black and transparent (magro), and it is one of the most perfect pigments we have. Another black is made of the skins of almonds, or the kernels of peaches ; this also makes a perfect and fine black. Another black is made in this manner : take a lamp full of linseed-oil, light the lamp, and put it under a clean baking-dish, so that the flame of the lamp shall be about the distance of two
or three fingers from the dish, and the smoke which comes from the flame shall strike against the dish ; collect the smoke together; wait a little; take the baking-dish, and sweep off the smoke (which is the pigment) into paper, or into some vessel; it does not require grinding, because it is already a very fine powder. Thus you may continue to fill the lamp with the oil, put it under the dish, and make in this manner as much colour as you require (2).
Chap. 38. Of the nature of a red pigment called sinopia (1).
There is a natural red pigment, which is called sinopia or porphyry. The colour is naturally transparent and drying. It bears grinding well, and the more it is ground the better it is. It is good for painting either on pictures or walls, in fresco or in secco. These terms, " fresco and secco," shall be explained to you when I treat of painting on walls. And we have said enough about the first kind of red.
Chap. 39. How to make a red pigment called cinabrese, used for the flesh-colours on walls, and its properties (1).
There is a red colour called light cinabrese, and I do not know that this colour is used any where but in Florence ; it is a perfect flesh-colour, either for painting on walls or in fresco. This colour is made of the finest and lightest sinopia; it is mixed and ground with bianco sangiovanni, as it is called at Florence (a white made of very white and pure lime). And when you have well ground together these two colours, in the proportion of two parts of cinabrese to one of white, make them into lumps the size of half a walnut, and let them dry, and keep them for use. This colour is very
fine for faces, hands, and naked figures on walls, as I have before said ; and sometimes you may make with it beautiful draperies, which on walls look like cinnabar.
Chap. 40. Of the properties of a red pigment called cinnabar (vermilion).
There is a red colour called cinnabar ; and this colour is made by a chemical process (alchemy), performed in an alembic, in a manner which would take too much time to explain. And if you would labour at it yourself, you may find many recipes, especially among the friars (1). But I advise you, that you may not lose your time in making experiments, to purchase what you want at the apothecaries' ; and I will teach you how to buy it, and to distinguish good cinnabar. Always purchase whole cinnabar, unbroken and unground ; the reason for this is, because it is often adulterated with minium (red lead), and with pounded brick-dust. Examine the whole lump of cinnabar, and that which is convex on the top and covered with needle-shaped filaments (2) is the best. Put this then upon the slab above mentioned, grinding it with clean water as much as you can — if you were to grind it for twenty years, it would be but the better and more perfect. This pigment requires to be tempered according to the situation in which it is to be used ; but of this J shall hereafter speak, and shall give you proper directions in another part of this work. But remember that it is not durable when exposed to the air ; it is more lasting on pictures than on walls, because by long exposure to the air it becomes black when applied to walls (3).
Chap. 41. Of the properties of a red pigment called minium (1) (red lead).
There is a red pigment called minium (red lead), which is also a chemical production. This pigment is only pipper to be used in pictures ; for if it be used on walls, on exposure to the air it suddenly becomes black, and loses its colour.
Chap. 42. Of the properties of a red colour called amatisto, or amatito.
There is a red colour called amatito. This is a natural colour, and is produced from a very hard and firm stone. It is so hard and firm that tools are made of it to burnish gold on pictures. It is very dark and pure, and as good as a diamond. The pure stone is of a maroon or purple colour, and is crystallised like cinnabar. Break this stone in a bronze mortar, because, if you were to break it upon the porphyry slab, you might split it ; and when you have broken it, put a small quantity on the slab, and grind it well with clean water ; and the more you grind it the better it will be, and the more perfect the colour. This pigment is proper for walls and fresco ; and it makes a colour such as cardinals wear, or a purple or lake-colour. It cannot be used in any other way, or in distemper (1).
Chap. 43. Of the nature of a red colour called dragon's blood (1).
There is a red colour called dragon's blood. This colour is sometimes used in miniature-painting on paper. Let it alone, however, and be not too anxious for it ; it will never do you much credit.
Chap. 44. Of the nature of a red pigment called lake.
There is a red colour called lake, which is an artificial pigment. There are many recipes for it; but I advise you, out of regard to those skilled in making it, to purchase the colour ready made : but be careful to distinguish the best, for there are .many sorts of it. If the lake be made of the shreds of cloth, or stuffs, it is very beautiful to the eye ; but beware of this, because it always retains some body by reason of the alum which it contains, is not durable, either tempered or not, and rapidly loses its colour. Be careful to shun this kind. But procure the lake which is obtained from gum, and is dry and transparent, and granulous like earth ; its colour is blood-red (1). This cannot be otherwise than good and perfect. Take this and grind it on the stone with clean water ;
it is good in pictures. It is also used on walls in distemper, but the air is destructive to it. Some there are who grind it in urine, but it is unpleasant, and soon becomes offensive.
Chap. 45. Of the nature of a yellow colour which is called ochre (1).
There is a natural yellow pigment called ochre. This pigment is found in a mountainous country, where there are veins of it like veins of sulphur ; and in these veins are found sinopia, verde terra, and other pigments. I found this pigment one day when my father, Andrea Cennini, took me to the territory of the Colle di Valdelsa, near the confines of Casole, on the outskirts of the wood of the comune of Colle, above a villa called Dometara. We came to a small valley, and to a rustic grotto, where, digging with a mattock, I saw veins of many colours, namely, of ochre, light and dark sinopia, blue, and white ; and it seemed to me the greatest miracle in the world that white should come from veins in the earth ; but remember that I made a trial of this white, and found it
unctuous, and unfit for the colouring of flesh. There were also in this place veins of a black colour ; and these colours were as visible on the earth here as the features on the face
of a man or woman. But let us return to the pigment ochre. I went about seeking every where with a knife for the veins of this colour, and I assure you that I never met with more beautiful or perfect ochre. I agree that it is not so bright as Naples yellow - it is a little darker; but for hair and drapery (as I shall hereafter inform you) you will never find any colour preferable to this ochre. It is of two kinds, light and dark. Each colour requires to be ground in the same manner with clean water ; and grind them well - they will be all the better for it. You must know that this ochre is a common colour, very useful in fresco-painting, as well as in other kinds of painting. It is used, as I shall tell you hereafter, in painting flesh, in drapery, in colouring landscapes, buildings, horses, and in many other things. This colour is in its nature unctuous.
Chap. 46. Of the nature of a yellow pigment called giallorino (Naples yellow).
There is a yellow pigment called giallorino, which is made artificially, and is very hard. ' It is as heavy as a stone, and hard to break. This colour is used in fresco, and is very durable on walls, and in pictures in distemper. It must be ground, like the other colours, with clean water. It is difficult to grind ; and before you grind it, it is better to break it to pieces in a bronze mortar, as I advised you to do with regard to the lapis amatisto.. And when you work with it, you will find that it is not a very brilliant yellow, and that without a mixture of some other colour, as I shall hereafter mention, it never makes bright greens, or the proper colour for herbage. Nevertheless, I give you to understand that this is a real stone, produced in mountainous volcanic districts ; therefore I say it is an artificial pigment, but not a chemical preparation (1).
Chap. 47. Of the nature of a pigment called orpiment.
There is a yellow pigment called orpiment. This is an artificial pigment, and a chemical preparation (1), and is very poisonous. It is a very fine yellow, like gold in colour. It is not good for walls, or in fresco, or in distemper, because by exposure to the air it becomes black. It is proper for heraldic painting. This colour, mixed with indigo, makes a green the colour of grass and herbage. It can only be tempered with glue. Physicians sometimes prescribe this pigment in some diseases which are brought before them. It is the most difficult colour to grind of any used in our art ; therefore, when you are going to grind it, put the quantity you want on the stone, and with that stone (that is, the muller) which you hold in your hand gently press it between the stones, mixing with
it a little broken glass, because the powdered glass, by its roughness, assists in grinding the orpiment. When you have broken it to pieces, put clean water to it and grind it as much
as you can, - and if you were to grind it for ten years, so much the better would it be. Beware of letting it touch your mouth, lest you should poison yourself (2).
Chap. 48. Of the nature of a yellow pigment called risalgallo (realgar, or red orpiment) (1).
There is a yellow colour called risalgallo (realgar, or red orpiment): this colour is also poisonous. It is rarely used by us, and only on pictures. It cannot be mixed with any other colour. If you wish to grind it, do it as I have before directed : it must also be ground with water ; and guard your person from contact with it
Chap. 40. Of the nature of a yellow pigment called zafferano (saffron<?).
There is a yellow colour made from a spice (spezia) called zafferano (saffron). You must put it into a piece of linen, upon a hot stone or brick; procure about half a glassful of strong lye ; pour it upon the saffron, and grind it on the stone. It will produce a beautiful colour for dyeing cloth or linen. It is good on paper. Do not expose it to the air, for it soon loses its colour. And if you would make the most perfect colour possible for grass, take a little verderame (verdigris) and some zafferano, in the proportion of one part saffron to two of verderame, and the most beautiful green will result. Temper it with size, as I have before directed.
Chap. 50. Of the nature of a yellow pigment called arzica(1).
There is a yellow pigment called arzica, which is a chemical preparation, and not much used. It is chiefly used by miniature-painters, and more by those in the neighbourhood of Florence than at any other place. It is a very fine colour, not durable when exposed to the air, is not proper for walls, but is good on pictures; mixed with a little azzurro della magna (2) and giallorino, it makes a beautiful green. It must be ground, like all the other bright colours, with clean water.
Chap. 51 . Of the nature of a green pigment called verde terra.
There is a natural green pigment which is an earth, and is called verde terra. This colour has many properties. First, it is a very unctuous pigment, and proper to use in faces, draperies, buildings, in fresco and secco, on walls, on pictures, and wherever you please (1). Grind it, as I have told you to grind the other colours, with clean water; and the more you grind it, the better it is. And if you temper it in the same manner as I shall direct you to temper bole, you may in the same way lay on gold upon verde terra. And know that the ancients never adopted any other manner of gilding than this with verde terra (2).
Chap. 52. Of the nature of a green called verde azzurro {blue or cobalt green) (1).
There is a green which is partly natural, but requires artificial preparation. It is made of azzurro della magna (German blue). This is called verde azzurro (blue green). Do not trouble yourself as to how it is made, but buy it ready made. This colour is good in secco, tempered with yolk of egg, to paint trees and grass, and also for grounds. Put on the light with giallorino (Naples yellow). This colour is of itself coarse and gritty. In order to preserve the colour, grind it very gently with the hand, because if it be too much ground, it will lose its colour, and be like ashes. It must be
ground with clean water ; and when you have ground it, pour clean water into the vase on the colour, and stir both well together ; then let it rest for an hour, or two, or three ; pour away the water, and the green will be most beautiful. Wash it in this manner two or three times, and it will be still finer.
Chap. 53. How to make a green with orpiment and indigo.
There is a colour made by mixing two parts of orpiment with one of indigo, and grinding them well together with clean water. This colour is good for heraldic painting ; and it is also used for painting rooms in secco. It can only be used with glue.
Chap. 54. How to make a green with verde azzurro (blue-green) and giallorino (Naples yellow).
There is a green colour made with verde azzurro and giallorino. This is proper for walls and pictures, and is tempered with the yolk of an egg. If you would make the colour more beautiful, add to it a little arzica; and if you would make it more beautiful still, add to it some azzurro della magna (German blue) ; pound some wild plums, and make verjuice, and of this verjuice put four or six drops to the blue. It makes a beautiful green ; but it fades when exposed to the air, and in time the verjuice entirely disappears.
Chap. 55. How to make a green with azzurro oltre marino (ultramarine blue).
A green colour may be made of ultramarine and orpiment. It requires some skill to mix these colours. First take the orpiment, and then add the blue (1). If you would have it incline to a light green, let the orpiment prevail ; if to a dark green, let the blue prevail. This colour is proper for pictures, but not for walls. Temper it with size.
Chap. 56. Of the nature of a green called verderame (verdigris).
There is a green pigment called verderame (verdigris). It is sufficiently green of itself, and is a chemical preparation, made of copper and vinegar. This colour is good on pictures, tempered with glue. Be careful never to mix it with biacca (white lead), because these two colours are mortal enemies. Grind it with vinegar, which it is its nature to retain ; and it makes a grass-green, most perfect and beautiful to the eye, but not durable. It is good on parchment, on paper, or on vellum, tempered with the yolk of an egg (1).
Chap. 57. How to make a green with verde terra and biacca (white lead), or with bianco sangiovanni and verde terra.
There is a green the colour of sage, which is made by mixing biacca and terra verde, tempered with the yolk of an egg. This is to be used on pictures ; when painting on walls or in fresco, mix the verde terra with bianco sangiovanni made of purified white lime.
Chap. 58. Of the nature of bianco sangiovanni.
There is a natural white pigment which, however, requires some preparation. It is prepared in this manner (1). Take very white slacked lime ; pulverise it, and put it into a little tub for the space of eight days, changing the water every day, and mixing the lime and water well together in order to extract from it all unctuous properties. Then make it into small cakes, put them upon the roof of the house in the sun, and the older these cakes are, the whiter they become. If you wish to hasten the process, and have the white very good, when the cakes are dry, grind them on your slab with water, and then make them again into cakes, and dry them as before. Do this twice, and you will see how perfectly white they will become. This white must be ground thoroughly with water.
It is good for working in fresco, that is, on walls, without tempera; and without this colour you can do nothing, - I mean, you cannot paint flesh, or make tints of the other colours which are necessary in painting on walls, namely, in fresco ; and it never requires any tempera.
Chap. 59. Of the nature of biacca (white lead).
There is a white pigment prepared chemically from lead, which is called biacca. This white is strong and brilliant, and is in cakes of the shape of drinking-glasses ( 1 ). To know the best sort, always select that kind the top of which is in the form of a cup. The more this colour is ground, the better it is; it is proper for pictures, and is sometimes used on walls ; but beware of it nevertheless, for in time it becomes black (2). Grind it with water; it will bear any tempera, and will enable you to make your colours lighter in pictures, in the same manner as the other white does on walls.
Chap. 60. Of the nature of azzurro della magna ( German blue, or cobalt) (1).
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There is a natural pigment of a blue colour, which is found in and around veins of silver. A great quantity is produced in Germany, and also in Sienna. If you would have it very good, you must grind it. When you are going to lay on grounds with this blue, you must grind a little at a time, with water, carefully ; for it is very difficult to grind. If you would use it for draperies, or to make greens, as I have before said, you must grind it more. This pigment is good on walls, in secco, and on pictures ; it may be tempered with yolk of egg, glue, or whatever you please.
Chap. 61. To imitate with other colours azzurro della magna (German blue).
To make a light blue, like the colour of the sky, take indaco baccadeo (indigo) (1), and grind it very fine, with water ; and for pictures, mix with it a little biacca ; and for walls, a little bianco sangiovanni. It becomes a sky-blue ; and must be tempered with glue.
Chap. 62. Of the nature of azzurro oltre marino (ultramarine blue), and how it is prepared.
Ultramarine blue is a colour more noble, beautiful, and perfect, than any other colour ; and its good qualities exceed any thing we can say in its favour. On account of its great excellence, I shall speak of it at length, and give you full directions for preparing it (1) ; and you must pay great attention to them, for they will bring you honour, and be of much service to you. And with this colour and gold (which are the great ornaments of our art) you may produce the finest effects (2). First take some lapis lazzari (3); and if you would know how to distinguish the best stones, take
those which contain most of the blue colour, for there is mixed with it what is little better than ashes. That which contains least of these ashes is the best. But be careful that you do not mistake for it azzurro della magna, which is as beautiful to the eye as enamel. Pound it in a covered bronze mortar, that the powder may not fly away ; then put it on your slab of porphyry, and grind it without water; afterwards take a covered strainer like that used by the apothecaries for sifting spices, and pound again as much as is required. But bear in mind, that although the ultramarine
becomes finer the longer it is ground, yet the colour is neither so rich nor so deep; and that the finer sort is fit for miniature-painters, and for draperies inclining to white. When the powder is prepared, procure from the apothecary's six ounces of resin of the pine, three ounces of glue (mastrice), and three ounces of new wax, to each pound of lapis lazzari. Put all these ingredients into a new pipkin, and melt them together. Then strain them through a piece of linen into a glazed basin, add to the mixture a pound of the powder of lapis lazzari, mix it all well together into a paste. And that you may be able to handle the paste, keep your hands always well anointed with linseed -oil. This paste must be kept at least three days and three nights, and must be stirred a little every day ; and remember that you may keep it for fifteen days or a month, or as long as you please. When you would extract the azure from the paste, proceed thus. Prepare two sticks, with handles neither too thick nor too thin, about a foot long ; let them be well rounded at the end, and polished. Then, your paste, being in the glazed basin into which you first put it, add to it a porringer full of lye, moderately warm ; and with these two sticks, one in each hand, turn and squeeze, and mix the paste thoroughly, exactly in the manner that you would knead bread. When
you see that the lye is perfectly blue, pour it out of the glazed basin ; take the same quantity of fresh lye, add it to the paste, and stir with the sticks, as before. When the lye is become very blue, pour it into another basin, and add more lye, as before. When this lye is very blue, pour it into another glazed basin; and continue to do so as long as the lye is tinged with colour. Then throw it away, it is good for nothing. Range all the basins before you on a table in the order in which they were drawn off 1 , that is to say, the first, second, third, and fourth ; then beginning at the first, with your hand stir up the azure, which by its weight will have sunk to the bottom, and then you will know the depth of the azure colour. Decide how many shades of the azure you will have, whether three, or four, or six, or what number you please, always remembering that the first-drawn extracts are the best, as the first porringer is better than the second. And if you have eighteen basins of extract, and you wish to make three shades of azure, take the contents of six basins and mix them together ; that will be one shade. Proceed in the same manner with the others. But remember that if you have good lapis lazzari, the azure from the first two extracts is worth eight ducats the ounce. The last two extracts are worse than ashes (4). However, your eye must
be accustomed not to spoil the good azure by mixing with the bad ; and each day remove the lye, that the azure may dry. When it is quite dry, put it into skins, bladders, or purses, as may be most convenient. But if the lapis lazzari be not very good, or after having ground it, if the colour be not deep enough, I will tell you how to give it a little colour. Take a little pounded kermes lake (grana) (5), and a little verzino (6), boil them together, but let the verzino be grated or scraped with glass ; and then boil them together with lye or a little roche alum. And when they boil, and you see that the colour is a perfect red, before you have poured the azure from the porringer (but which must be quite dry, and free from lye) add to it a little of this lake and verzino, and with your finger mix them all well together; and let them remain to dry without sun, or fire, or wind. When dry, put it into a skin or purse ; it is good and perfect And keep this secret to yourself; for it is a great acquirement to know how to make it well. You must know also that it is rather the acquirement of youth than that of men, because they remain continually in the house, and their hands are
more delicate. Beware especially of preparing it in old age. When you would use this azure, take as much as you want ; and if you are going to work on white dresses, grind a little on your stone. And if you want it for laying grounds, grind it a little on the stone (which is to be previously well washed and clean) with very clean water. And if the azure should be dirty, take a little lye or clean water, and put it into a vase, and stir them well together for a short time, when the blue will be quite clean. I shall not treat of its tempera, because I shall hereafter describe all the temperas proper for every colour to be used on pictures, on walls, on iron, on paper, on stone, or on glass.
Chap. 63. Shewing that it is necessary to know how to make brushes or pencils.
As I have told you the names of all the colours individually which are used with pencils, and how they are ground (these colours must always be kept in a box well covered, and under water), I will now tell you when to use tempera, and when not. But you must first know how to make use of them, and this you cannot do without brushes. Therefore we will leave these subjects for the present, while I teach you how to make the brushes, which you are to do in the following manner.
Chap. 64. How pencils of minever are made.
In painting two kinds of pencils are necessary, namely, pencils of minever and of hog's bristles. Those of minever are made in the following manner : - Take the tails of the minever (for no other are good), and these tails must be baked, and not raw (1). The furriers will tell you so. From the tip of such a tail draw the longest hairs, and collect the tips of many tails, so that from six or eight points you may make a soft pencil fit for laying gold on pictures, that is to say, to wet it with in the manner that I shall direct you hereafter. Let us return now to the tail, which you are to take in your hand, and select the straightest and firmest hairs from the middle of the tail, and lay them in small bundles ; soak them in a glass of clear water, then press and squeeze each bundle with the fingers. Then cut them with scissors ; and when you have made many bundles, tie them together any thickness you please for pencils, so that they can be put into the quill of a vulture, of a goose, of a hen, or of a dove. When you have made them in this manner, laying the points very even, take waxed thread or silk, and with knots fasten them well together, each sort by itself, the size you would have your pencils. Then take a quill, of a size corresponding to that of the bundle of hairs, and cut off the end of the quill, and put the bundle of hairs into the quill. Take care that
the point project as far as you can squeeze it out, so as to leave the point firm, and the firmer and shorter it is the better. Then make a small stick of maple, larch, or chestnut, or any other good wood ; make it smooth and clean, scrape it into the form of a spindle, of such a size that it shall fit tightly into the quill, and be about a span long (2) ; and this is the way to make pencils of minever. It is true that the pencils of minever are of various kinds ; for instance, some proper for laying on gold, some for putting on fiat washes, which require to be cut (mozzetto) a little with the scissors, or rubbed upon the porphyry stone, that they may separate a little. Some pencils should have a perfect point for drawing outlines, and some must be very small and fine for certain
very minute works and figures (3).
Chap. 65. In what manner pencils of hog's bristles are to be made.
Pencils of hog's bristles are made in this manner. First take bristles from a white pig, which are better than those from one that is black (but they must be from the domestic pig), and make a large brush, in which you must put a pound of bristles, and bind them to a large stick (1). If you like, you may use these brushes for whitening and washing walls which are to be covered with mortar (smaltare), until they become very soft Afterwards unfasten this brush, and make the bristles up into other brushes. Let some of them be of the kind which are called cut pencils (pennelli mozzi), in which the hairs are all of equal length ; and some should be pointed, and you must have them of all sizes. Then make sticks of the wood formerly mentioned, and bind each bundle
with a double waxed thread. Introduce the point of the stick into the bundle of bristles, and bind it evenly half the length of the bristles, and more upon the stick, and finish all
the others in the same manner.
Chap. 66. How to preserve the tails of the minever from being moth-eaten.
If you would preserve the tails of the minever so that they should not be moth-eaten, and the hairs should not fall off, steep them in kneaded clay or chalk, stick them tight into it, hang them up, and let them remain so. When you would use them, or make them into pencils, wash them well with clean water.