ABSTRACT—Each painting must be treated according to its special needs which are, in part, a result of its history. To determine this history is difficult due to the lack of reliable records. Changing attitudes towards deterioration and towards preservation, changes in fashion, and, of course, the type and quality of the treatment itself have affected a painting's structure and appearance. Two other important influences on the care of pictures have been the unfortunate view that the lining process is separate from the rest of the treatment procedure, and the pressure from dealers and collectors to have a painting appear to be undamaged. If a picture is to be properly cared for, its surface appearance cannot be the only consideration. If a painting is not structurally secure, it will not survive. The present move to eliminate the lining process ignores such structural problems as inner cleavage and the additional stress put on pictures today by subjecting them to travel. Of all the methods of lining and the adhesives available, not one is suitable for all paintings. The choice must be based on each painting's particular structural problems and on a knowledge of the effects of the method and material over a period of time. The advantage of wax-resin linings is that, when properly used, the adhesive penetrates and consolidates the structure. Furthermore, this process has been in use for a long time and most paintings so treated have shown a good survival rate.

Those of us who aspire toward professional status adhere to the maxim that the artifact in treatment makes the rules. Where paintings are concerned, their state should dictate the procedures which we may or may not undertake to help them survive. Supposedly, canvas paintings are lined to make them last longer and/or diminish the ravages they have suffered from neglect and abuse. Our most uncontroversial source for operative directives should be the paintings themselves. This does not happen to be true. Any painting old enough to boast a role in history can present such an adulterated structure that its technical examination is bound to be strongly colored by interpretation. There is a woeful lack of objective realities in evaluating the requisites of a canvas painting. We have too often been unwilling to admit that we are faced with incomplete understanding of the kind and extent of alterations a canvas painting may have experienced. We have been unwilling to build case histories slowly and with open minds. I do not mean to imply that ours is the only field in which practitioners have rushed to find answers first and then looked about for supporting evidence, but I do feel that a vast proportion of our disagreements may be placed at the doorstep of impatience.

As Jacques Guillerme emphasizes in his very amusing book, “L'atelier du temps,”2 the element of time has been viewed with an unacknowledged ambiguity. Art historians, art lovers should have good reason to hate what destroys, decomposes paintings, but oddly enough they seem to find the marks of wear and tear enchanting. A venerable object which emerges from the abyss of centuries without being tarnished by a curious reaction invites a kind of suspicion. The author of this entertaining volume makes the cynical point that art lovers exhibit a vein of necrophilia: they cherish the ravages of time as sweet and precious, not seeing it for the embalming it truly is. There is no question but what the passage of time inscribes itself cruelly on the body of a painting, nor that man's part in this calvary is any less crucial than that of natural forces. What we ignore is that the quality of seeing what has already happened fluctuates with the norms of time. Aesthetic evaluations are no less fickle than the fashions which form them. The tastemakers of today were born and will die as their familiars before them. The subjective approaches to a painting will continue to remain subjective.

How much objectivity exists in contrast? I doubt there is one among us who will not agree that in the laminates of paintings, old or new, mighty few substances are chemically pure. But while we give lip service to the existence of incredible variables in the composition of paintings, we still continue to victimize ourselves. We transform observations into dogmas, deductions into facts. In the business of identification of materials, the study of their properties and interactions, a serious proportion of what we view as our scientific documentation hinges on someone's selection of the nearest resembling curve on a graph or the closest predominance of peaks on a scan. True, we have a fine body of factual analyses from which sound comparative data may be extracted. There remain, however, far too many unwarranted conclusions based upon inadequate scientific evidence and no small portion of these mutate rather extraordinarily into absolutes.

There is a similar want of caution in our attitude toward historical testimonies. The recipe books and storied accounts which we have inherited were compiled by amateurs, by amanuenses, or at worst simply by yarnspinners. Very few who wrote performed the activities which they described. Most of the recorded material is second or third hand and all of it suffers from hearsay. Anecdotal embellishments inevitably receive attention, they are so much more amusing than the bare bones of ledgers and archives. Therein lies the mischief. Generally, the information which should not be questioned (or as in multiple instances repudiated) is lean, must be sieved from the inroads of secrecy and the bombast of braggadocios. There are accounts, such as some of us keep today, which provide invaluable tidbits of guidance with all too often the basic directions we yearn to know omitted, omitted because they were so familiar that to repeat them would have been redundant. This failure to reiterate common knowledge puts an unwarranted burden on future generations. All of us should endeavor to detail our activities in terms which will be perennially comprehensible. If we do not do this, concepts of how we worked will be extrapolated from statements in the news media and popular press, or in those writings which are reminiscent of exactly what frustrates us with our inherited scripts.

Supposedly, an era of civilization may be evaluated by the art forms it produces. As a matter of fact, a civilization reveals itself far more clearly by the relationship it exhibits toward what it has inherited from previous times. It could hardly be claimed that any period much before two hundred and fifty years ago showed noticeable interest in preserving its artistic heritage. The tenuous regard for the past which barely lifted its head in the earlier centuries scarcely equates with principles of preservation. Badly damaged works of art were discarded. Those which their owners elected to retain were assigned to artists for renewal: the statues to sculptors, the paintings to painters. Artists so employed were not all inept. Among the famous3 who reworked creations of their predecessors were Benozzo Gozzoli, Gentile and Giovanni Bellini, Primaticcio, Frans Hals. Some even signed their restorations with pride. The additions, the undisguised changes which revitalized the paintings on which they labored, were acclaimed as the marks of veneration which they really were. Neither the hands which placed them, nor the eyes which enjoyed them, found anything improper or false in brilliantly executed innovations.

Although the 18th (and even the 17th) centuries were reputedly less indifferent to the unfashionable vestiges of their past than were the periods before them, it is impossible to estimate the number of masterpieces lost or destroyed. Creditable reworking and renovating were less common than neglect and abuse. Taste was the critical factor. For a society with a collecting mania such as ours, it is inconceivable that the now revered tapestry of the APOCALYPSE (from Angers) found no buyer,4 was disunited for brutal usage, one section even serving to protect a parquet floor while the ceiling above it was repainted. A panel painting by Justus of Ghent was used in Florence, of all places, as a table top. Nobody protested. Nobody wanted what was out of fashion. The casual reports culled from contemporary references make horrifying reading. We should never minimize the experiences endured by the painting masterpieces which have survived.

Not the least of these experiences was initiated by our occupational forebears. The lining of paintings on fabric, mentioned occasionally in earlier inventories, seems to have flourished5 in the 18th century in conjunction with the techniques for transfer and for cradling of panel paintings. Lining adhesives listed in the 1750's mention glues and pastes with additives ranging from treacle to garlic juice. Drying appears to have taken place under pressure. Strip lining was practiced. Moisture was recognized as an assist—old canvasses advisedly exposed to the humidity of damp cellars several days before a lining operation. Mention was made of protecting paint surfaces with facings of papers. Blisters were treated with injections of glue after having been perforated by a needle. Forms of impregnation were described apparently involving linseed oil and pressure with a warm iron. In 200 years we may have increased our repertoire, and added sophisticated instrumentation, but most of the basics were being assessed long before we were born.

Just as it has been claimed that in the 20th century conservators went berserk over wax-resin linings, at the close of the 18th century our ancestors most surely went berserk over transfer.6 They vied with one another in quantity and ruthlessness, replaced original grounds with new applications of white lead, competed in the number of transfers they could complete in a given time span. Archival reports on their victims read like battle casualties listing personal friends, so many of the titles and artists are honored intimates. The bitter complaint that too often neither a transfer (nor a cradling) was dictated by the state of the painting, rather was performed as a tour de force for the aggrandisment of the demonstrating restorer, could be read for yesterday or today merely by changing the action deplored. Restorers were very, very busy, and there is no doubt but what paintings paid the price. It took major disasters such as the delamination7 of Raphael's St. Michael only 15 years after it had been transferred (in 1751) to force a slowdown in the wholesale replacement of original supports. One Parisian coterie, in 1793, accused another of operating on precious paintings like the fabled harpies who destroyed everything they touched.8

Acrimonious screams were not limited to any one locale or to any country. All over the continent, and later on in England, investigation followed investigation and the decisions of one commission on the handling of restorations were questioned by a series of its successors. Not all energies were wasted in fruitless friction. Uniquely inspiring was the work of Pietro Edwards who, by Senatorial decree September 3, 1778, directed the restorations on the pictorial treasures of Venice until the end of that Republic. This remarkable man kept extensive records9 on the paintings he treated listing the materials used, systems employed, and their costs. The outline he drafted for a public school of restoration under the aegis of the Venetian Academy of Fine Arts, although it never came into being, could model for a successful funding appeal to our own government. Unfortunately, the quality of this enterprise deteriorated with his death. Opportunity to peruse the original manuscripts, not just the accounts,10 from his less than revered son, Giovanni Edwards O'Kelles, would greatly benefit our profession. I sincerely trust that the translation-in-progress by Bettina Raphael may reach publication fairly soon.

Pietro Edwards made a statement11 on the nature of paintings which is close to my heart. Translated from the Italian he said, the natural substances (of paintings) consist of heterogeneous elements artificially held together contrary to their natural affinities. I find this an extraordinarily acute observation, and doubt there is a colleague who at one time or another has not reached the same conclusion, even if subconsciously.

As the 19th century advanced, information on restorative practices became more extensive if not necessarily more reliable. At the turn of the century oils and resins had been added to certain lining mixtures.12 These were found to oxidize and to embrittle fabrics. The glues and pastes had been found to make canvasses vulnerable to attack from microorganisms. Mentioned fleetingly in the 1700's, beeswax, as an adhesive base, gained acceptance especially for linings undertaken in climates with prevailing high humidity. Labeled the “Dutch” method,13 wax-type linings did not become habitual much before the 1860's to 1870's. Possibly peripheral to this, but worthy of note, is the fact that the mid-19th century was fascinated by the use of wax as a painting media.

According to reports, however, the techniques for glue and glue-paste linings, which had been perfected in Paris at the end of the previous century, acquired the orthodoxy of tradition. This is true to the present day and continues to be a tradition practiced in many parts of our world. Also in practice14 well over a hundred years ago was the placement of canvas paintings in temporary work frames to permit both front and reverse to be treated simultaneously. At this era, facing tissues existed in variety, were renewed, replaced with specific intents as circumstances directed. Hot irons, heavy irons and variations of pressure methods had disparate advocates. Things reached such a finality of execution that contemporary practitioners held paintings which they had unified were guaranteed to last forever.

Not everyone basked in this euphoria. Justified and unjustified doubts nagged the custodians responsible for collections. Inquiries on the inequities in the cleaning of pictures moved Eastlake,15 much as we ourselves are moved, to ponder the advisability of seeking aid from scientists. He is said to have opted against it only because their presence, as he expressed it, “would complicate the machinery very much.” Perhaps scientists do complicate machinery. Neverthless, it is to one of them, Dr. Pettenkofer, that we owe an endless debt. Pettenkofer's services to our field suffered a devaluation parallel to the chronological lessening of benefits from his regeneration system. He did, however, instigate16 the concept that every important work of art should have its individual technical dossier. If the suggestion had been followed, even from the time he first urged its adoption, we would possess an assemblage of former diagnoses, accounts of previous operations which would make the treatment of paintings which come to our hands that more sensitive to experiences previously endured. We are in sore need of such case histories if we presume to pass on to unborn generations more than the travesty of pictorial remains which M. Guillerme so deplores.

Most of the historical information I have briefly sketched for you has been extracted from the monumental tomes written by our good friend, Roger Marijnissen. I find it extraordinarily apt that at this point in his chronology he comments on two conditions which I see as over-powering factors in misdirecting our ideas on the lining of canvas paintings. Marijnissen draws attention to the fact that from the end of the 18th century the lining of paintings was viewed as a specialty of restoration. He mentions that even at the time of his writing, 1966, it was possible to find on the reverse of paintings they had lined the marks of the great 19th century experts in this specialty, Hopman of Amsterdam and Morrill of Leedham.17 Although other nations boasted experts with this particular skill, in the minds of many lining was not only seen as a separate function, it was held to be a minor operation requiring little technical knowledge. This latter viewpoint has prevailed to the present. Whether well done or botched, for the past 150 years lining has generally been a separate experience for a painting performed by someone other than the person who determines the visual appearance of the whole. It has also been an experience quite alien to the skills of the restorer who cleaned, compensated and revarnished.

The other comment, which I find quite as serious an influence on our current attitude toward lining, follows an account of rantings directed against inept restorations. Marijnissen says that even in the 19th century restorers were not held solely responsible for the evidence of their malpractice.18 It was recognized that dealers and collectors contributed to the perpetuation of certain malfeasances. Repair of damages was supposed to be played down, and collectors kept in ignorance of the actual state of their purchases. He concludes that when integrity came in conflict with financial gain these ancestors of ours could not all be expected to cleave to paths of rectitude and renounce wealth.

Early steps toward international exchange of information in our field were the conference in Vienna, 1905, and that in Rome, 1930. How far we succeeded, at least verbally, in reaching collaboration is evidenced by our own international organization and by the continued labors in ICOM and UNESCO committees. Pertinent to the lining controversy is an account in MUSEUM, 1960, in an article on fabric paint supports. It states:19 “Fundamentally, opinions differ on two points only, but these are of vital importance: (a) Should lining be used as a preventative measure, even when there is no urgency? (b) Is one of the (then two) main methods of lining to be preferred…?” The report goes on to say the first question can be settled only after an appraisal of each individual case. “An examination” it states, “will lead to the right solution.” On the second it holds “that certain preferences will be dictated by studio traditions, by climatic conditions…” The cogent issues are here in a nutshell even if ramifications of our disagreements are over-simplified.

The last thing anyone wants is a universal doctrine. None of us would welcome our own displacement, and each of us cannot but dislike the thought of being reduced to the role of instructed operator. Such authoritarianism would be as hazardous as it is unrealistic. We should not presume that a local tradition is necessarily a national characteristic. What I believe should be and has not been weighed in previous discussions is the impetus for certain systems and the background from which prejudices have evolved.

Among those who urge a limited reliance on lining as a preservative method for canvas paintings, emphasis is placed on the two dimensional aspects of a painting with furor over surface aesthetics. I decline to be led into a Mare's Nest laced with arguments over how a painting should look. I would not be in this work if I did not love paintings. I love them my way which may or may not be your way. I find all assumption of absolutes in aesthetics foolhardy. Nevertheless, as a practicing conservator of paintings I have, and will, accede to strong prejudices regarding visual appearance of an individual painting, and adjust my treatment accordingly, PROVIDED that the prejudice in no way endangers the survival of the painting.

Yes, I know, here lies the rub. Who is to make the appraisal of danger? The UNESCO committee said: “An examination will lead to the right solution.” There are good examinations, and bad examinations, and purported examinations which never took place. There is the statement on condition deduced by the so-called magic eye. It is possible to conduct an examination so the results fit prerequisites of an interested party. This should and could be an uncontroversial approach. Unfortunately, too many decisions hinge on unwarranted whims of arrogance rejecting not only the use of a binocular microscope but even a magnifier powerful enough to reveal possible evidence of delamination. The vital dimension—and I use “vital” in its literal sense—of any work of art is its thickness. Critical to the survival of a painting is the bonding of its laminates, the state of its structure in depth.

Years ago Nathan Stolow gave me one of my favorite quotes: “A work of art lasts as long as its parts stay stuck together.” No attentions, however esoteric to either surface or fabric reverse, will serve to prolong the existence of a painting with internal delamination. There are few papers from the recent Ottawa20 and Greenwich21 lining conferences where the authors who advocate avoidance of lining show any appreciable concern for consolidation of structure. They make mention of setting down cleavages, securing tears, systems for effecting the removal of previous linings and their adhesives, even, when exigencies demand, some interesting variations on techniques for new linings. I note an overall want of intimacy with structural reconsolidation. I believe this can be explained by the 150-year hiatus during which lining was relegated to the liners. If, for example, we keep this fact in mind, the remarks of Mr. Percival-Prescott seem less incredible. He objects, and I quote,22 that “the fundamental treatment of the painting as a whole …” and here in a parenthesis he puts a statement which confirms the dichotomy in his background experience, he says, “(FOR THAT IS WHAT LINING IS),” and his objection is that it “should receive only minimum attention and time.” Obviously, the common occurrence for this colleague was that a restorer did only remove varnish and overpaint and subsequently retouch and revarnish. It becomes understandable why so many familiar techniques of stretching and prestretching described in his writings should appear to Mr. Percival-Prescott as innovations. Some of his details are innovations and stimulating so. However, in defense of kith and kin may I flatly state that for over forty years there have been conservators in these United States who consistently viewed lining as a major portion of their work, and who have proceeded under the concept that an original canvas should be cautiously and carefully returned to optimum planar unity before it is joined with a lining support.

To one phase of Mr. Percival-Prescott's proposals I take exceptional issue, the suggestion that his moisturizing methods by themselves may gratifyingly prolong the life of a fabric painting. Responsibility for rebonding in depth may not be dismissed. I cannot justify any attempt to force substances in an aged canvas to resume an adhesive role which they have already indicated they were unable to continue. To propose the visual improvement of a pictorial plane by a system which ignores the weakening effect it will have on interior bonds seems to me an invitation for the parts of a painting to become unstuck. Temporarily, this may give the semblance of success, but any “simple relaxation” of the internal bonding in a painting without reinforcement of its ability to go on functioning encourages the layers of a painting to fall apart.

If there are those who seriously want to eliminate unnecessary linings—and why not include also unnecessary cleanings and unnecessary revarnishing—they had best unite to eliminate loan shows. How about this deadly exposure to the extremes of shock, to the abuses at the hands of those who crate and uncrate, who install and remove, let alone those who come to vandalize? May we realistically deny that this is the acute urgency faced by all paintings? Very, very few are those who may beg immunity from this world-wide sickness. In a way it was funny when the New Yorker reported that the MONA LISA passed Whistler's MOTHER on the New Jersey Turnpike. That highway has a high accident rating. I would be curious to learn what their computers told the insurance companies.

So thousands of visitors came to see these masterpieces in the flesh, people who might otherwise never have viewed the real article. Under what ease of circumstance and for how long did they view them? Were these isolated instances of spiritual enlightenment stirred by the physical presence of these two rarities, added to the heady rise in body count of attendence, the flattering coverage in news media, and the burgeoning prestige for the exhibiting institutions, an appropriate balance to the risks? Weigh the grim uncertainties of travel in this 20th century. What does this cavalier pulling about of great art say for the relationship of our so-called civilization to its heritage? Is our conduct so much less callous than the use of an outmoded panel painting as a table top, or a great tapestry to shield a floor from paint drips?

Some lining methods and materials may be as horrendous as that which a painting must endure in a loan show, but I find it Hobson's choice in evils, and high time to admit this.

It is perfectly true that we bolster the superiority of our chosen lining procedures by flaunting the worst examples we can find of systems we reject. There have been bad glue linings, bad wax linings, bad any form and fashion of linings. There have also been excellent ones. I even suspect there may have been good linings accomplished with the cements that make me shudder like epoxies, asphaltums and lead white—but I doubt it! Let us agree to disagree and cease pretending that adhesives with which we are not familiar, and systems whose intricacies we have yet to master, are wrong, and ipso facto detrimental to the welfare of canvas paintings. Colleagues past and present have produced superb linings with the materials and means peculiar to their expertise. The crucial test of our work is time.

In 1977 we have a myriad of lining adhesives. Obviously, discretion is wise, and haste deplorable, in responding to the claims enunciated for new products until these may have their efficacy thoroughly tested. We have hot and cold adhesives, thermoplastic and thermosetting, liquid and solid, aqueous and non-aqueous, wax based, resin based, pressure sensitive, pressure requisite, penetrating and non-penetrating, almost any category of an adhesive imagined, at least imagined at this point in time. As for the lining systems, they range from hand irons, presses, to assorted vacuum tables, vacuum envelopes, unpressured suction, and with and without direct or indirect heat sources. I urge all of you who have not yet been exposed to these infinite variations to read the papers of the Ottawa and Greenwich conferences, and read our own organizational publications describing current practices.

What I also urge is that you read this often confusing array of information without taking any of it as the final solution. No system and no material is a panacea. The painting in treatment must make the rules. Use the system you know the best until you have mastered the intricacies of another. If you cannot master a method, but are sufficiently intelligent to see its advantages for a particular problem painting, be professional enough to send that painting to the colleague most expert in that method. Take the time to examine. Take the time to make tests. All of us make errors, to repeat errors is not excusable. Weigh the decision you make in the light of providing requisite security for the painting. Is travel part of its future? Do not wrap yourself with cold comfort that in THIS case the travel will be completely secure. There can be no such circumstance.

In defense of wax-resin linings, may I point out they have been around quite a long time. Many of the paintings all of us enjoy have been so preserved and no few of them for over a century. Although I will certainly not deny that misuses of wax adhesives have stained paintings and discolored fabric supports as well as absorbent paint, much of that abuse followed the misguided notion that a single discovery may prove a panacea. I hold that wax-resin adhesive correctly used supplies an optimum means for the consolidation of paintings on fabric supports. I find the argument that wax adhesives are alien to the natural substances in a painting specious. Do we, in our endeavors to find consolidants for artifacts of stone, clay, wood or cellulosic fibers, limit ourselves to chemical properties which correspond with the elements in these structures? By no means. We are governed by our desire to preserve artistic integrity of what we treat, and we prohibit ourselves from using curative compounds which alter appearance. Excepting those unfortunate instances of error in judgment, I refer to inappropriate application of this adhesive, I am convinced that much of the furor against the use of wax and wax-resins for lining is dealer inspired.

Where the added fabric has been saturated with wax adhesives the reverse of a canvas painting shouts out loud that it has experienced preservative treatment. The non-penetrating adhesives force no recognition of their presence. In fact, the deception need not be emphasized because the majority of collectors and curators still need a tactful explanation that an unsullied lining fabric is not the reverse of an original support. Why not make the dealer happy, continue the purchaser in ignorance of the state of his acquisition? I find this self-defeating. Survival pattern is what matters. A well-preserved painting appreciates in value, monetary price is hinged to the wrong factor. I resent the implication that a dealer's concept of what governs monetary price should dictate the choice of a lining adhesive or, worse still, the avoidance of this protective care. The misconception has its roots in history, but it remains an inexcusable hypocrisy.

It is regrettable that in a field which has yet to achieve the status of a licensed profession, and where formal education is still in its academic infancy, fanaticisms have so persistently been invested with infallability. Objective conclusions are not reached by emphasis of the peculiar. Random facts do not constitute science. As a rule, professions increase the benefits accruing to those whom they serve by nourishing development of their differences in approach and in performance. The competent practitioner is always that person who selects the procedure most appropriate to the nature of the demand. “Appropriate” implies personal response to observed characteristics. “Select” implies freedom to make an educated choice. To claim superiority of any single material, method of instrumentation over all others seems to me quite as disasterous an invitation as shouting insults to passersby from the windows of a glass house.

REFERENCES

Professor of Painting Conservation and Program Administrator, Conservation of Historic and Artistic Works, Cooperstown Graduate Programs, Cooperstown, New York 13326.

Guillerme, Jacques. L'atelier du temps: Essai sur l'alt�ration des peintures. Paris: Hermann, 1964.

Marijnissen, R. H.Degradation, Conservation et Restauration de l'Oeuvre d'Art, 2 vols. Bruxelles: Editions Arcade, 1967.

Marijnissen. Degradation, Conservation d'Art, Vol. I, p. 28.

Ibid., pp. 34, 35.

Ibid., pp. 35–37.

Marijnissen. Degradation, Conservation d'Art, Vol. II, #86.

Ibid., #174.

Raphael, Bettina. “The Edwards Manuscripts.” (Research work in progress. Smithsonian-Rome Centre Grant, Cooperstown Graduate Programs, 1971.)

Keck, Caroline K. (Courtesy of the Rome Centre, we received a microfilm of the manuscripts compiled by Giovanni Edwards O'Kelles. These were photocopied and have been sketchily translated for references.)

Raphael. Edwards Manuscripts,

Marijnissen. Degradation, Conservation d'Art, Vol. I, pp. 43–44.

Ibid., p. 45.

Ibid., p. 45.

Brommelle, N. “Studies in Conservation,” “Material for a History of Conservation,” Vol. II (1955–6) pp. 176–186.

Marijnissen. Degradation, Conservation d'Art, Vol. II, #239.

Marijnissen. Degradation, Conservation d'Art, Vol. I, p. 45.

Marijnissen. Degradation, Conservation d'Art, Vol. I. p. 62.

Museum, Vol. XIII, no. 3. (Paris: UNESCO, 1960) p. 152.

National Gallery of Canada. Seminar on the Lining of Paintings, Ottawa, April 6–8, 1976. Proceedings edited by MervynRuggles, Head.

National Maritime Museum. Conference on Comparative Lining Techniques, April 22–26, 1974. Greenwich, Great Britain.

Ibid. “Prestretched Low Pressure Lining Methods” (including vacuum envelope), Ronald Chittenden, Gillian Lewis, Westby Percival-Prescott, 20 pages.

Section Index