{"product_id":"klucel-g-500-g","title":"Klucel® G (500 g)","description":"\u003ch2\u003eKlucel® G (500 g) — the cellulose ether that also works without water\u003c\/h2\u003e\n\u003cp\u003eKlucel® G is \u003cstrong\u003ehydroxypropyl cellulose\u003c\/strong\u003e — abbreviated HPC —: a non-ionic cellulose ether manufactured by \u003cstrong\u003eAshland\u003c\/strong\u003e (formerly Hercules) and distributed by CTS, with CAS number — the international register that identifies every chemical substance — \u003cstrong\u003e9004-64-2\u003c\/strong\u003e. It dissolves \u003cstrong\u003ein cold water and in most polar organic solvents\u003c\/strong\u003e — ethanol, methanol, 95 % isopropanol, dimethyl sulfoxide, propylene glycol —, and that dual solubility is its whole point: it allows consolidating and adhering on works where introducing water is not an option. Two traits set it apart from what resembles it: on heating in water it \u003cstrong\u003edoes not gel, it precipitates\u003c\/strong\u003e — exactly the opposite of methylcellulose —, and in an organic solvent heat speeds up dissolution instead of spoiling it.\u003c\/p\u003e\n\n\u003ch3\u003eWhat is it used for?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eAdhering and repairing works on paper without introducing water\u003c\/strong\u003e, dissolved in ethanol at 1-2 %, when wetting the support is ruled out.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eLocal consolidation of leather with \u003cem\u003ered rot\u003c\/em\u003e\u003c\/strong\u003e — the degradation of vegetable-tanned leather that turns it into a reddish powder —, applied in alcohol: it reduces surface powdering. That leather darkens irreversibly the moment it meets water, and there lies the reason for the alcohol route.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eFixing powdering layers and pastel\u003c\/strong\u003e, in a thin layer and at low concentration.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003ePaper and parchment with sensitive inks and corrosion\u003c\/strong\u003e — iron gall ink and copper corrosion, where treating with non-aqueous polymers is standard practice.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eThickening polar solvents, acids and bases\u003c\/strong\u003e for controlled cleaning: alcohols, amines, dimethyl sulfoxide. \u003cstrong\u003eIt does not thicken non-polar ones:\u003c\/strong\u003e aliphatic and aromatic hydrocarbons and petroleum distillates are not solvents for it.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eWhy choose Klucel® G?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eIt is the grade the field uses.\u003c\/strong\u003e In the Getty Conservation Institute survey of 155 conservators from the Book and Paper Group of the American Institute for Conservation (AIC), grade G was the hydroxypropyl cellulose used almost exclusively.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eThe viscosity of the solution does not vary between pH 2 and 11\u003c\/strong\u003e — manufacturer's data —, which allows thickening the acids and bases in common use in the field. The solution is prepared for immediate use; if stored, it keeps best between pH 6 and 8.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eIt forms no peroxides\u003c\/strong\u003e (0.00 milliequivalents per gram at every time point of the Getty test) and its \u003cstrong\u003ephotochemical stability against visible light and near ultraviolet is excellent\u003c\/strong\u003e. On ageing it does not become insoluble: it keeps redissolving in its own solvent. What it is \u003cstrong\u003enot\u003c\/strong\u003e — and this is told in full below — is the most thermally stable of the cellulose ethers.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eFlexible film without plasticisers.\u003c\/strong\u003e The manufacturer states it: Klucel films are flexible in themselves, do not turn tacky at high humidity and act as a barrier against oils and greases.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eViscosity maximum in a hydroalcoholic mixture:\u003c\/strong\u003e 7 parts water and 3 parts alcohol by weight give 500 mPa·s at 2 %, against 270 in water alone and 210 in ethanol. With the same product, almost twice the body.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eThe limits, stated\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\u003cstrong\u003eIt is not the most thermally stable cellulose ether.\u003c\/strong\u003e The Getty classified it in 1990 as thermally \u003cstrong\u003eunstable\u003c\/strong\u003e, and in chain scission grade G came behind carboxymethyl cellulose and methylcellulose. The condition that defuses this is set by the very source that classified it: applied \u003cstrong\u003eat 1 or 2 % and in a thin layer\u003c\/strong\u003e, which is how it is used, discolouration, if it occurs at all, is \u003cstrong\u003ebarely perceptible\u003c\/strong\u003e. In full, in the frequently asked questions.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eMedium adhesive strength.\u003c\/strong\u003e That is how the distributor describes it, and the conservators surveyed by the Getty agree: it is not a strong adhesive. It bonds paper and board and consolidates; it does not solve a joint under mechanical load.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eInsoluble in water above 45 °C, and it precipitates — it does not gel.\u003c\/strong\u003e Heating the water to speed up dissolution achieves the opposite. Precipitation is completely reversible: cooling below 40 °C with stirring redissolves it and restores the original viscosity.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eOn leather with \u003cem\u003ered rot\u003c\/em\u003e, it consolidates at the surface.\u003c\/strong\u003e It reduces powdering, but it does not give strength back to the leather matrix and \u003cstrong\u003eit neither reverses nor halts the deterioration\u003c\/strong\u003e. It can leave tidelines, gives a matt finish, and the film breaks with repeated flexing.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eAs a fixative, take care with organic pigments.\u003c\/strong\u003e A higher moisture content in vehicles such as this one can accelerate the fading of organic pigments — carmine lake is named explicitly —. The support should be kept close to pH 7 before and after treatment.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eMixed with resins that react with its free hydroxyl groups, the film may become insoluble\u003c\/strong\u003e, and high temperature and low pH accelerate that curing. That is the real limit of its reversibility.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eDrying an aqueous application with heat can cause blushing\u003c\/strong\u003e and spoil the film.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003ePack size and storage\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePack size: \u003cstrong\u003e500 g container\u003c\/strong\u003e.\u003c\/li\u003e\n\u003cli\u003eStore between \u003cstrong\u003e5 and 35 °C\u003c\/strong\u003e, in a dry, well-ventilated place, with the container tightly closed and upright.\u003c\/li\u003e\n\u003cli\u003eShelf life: the manufacturer \u003cstrong\u003edeclares no expiry date\u003c\/strong\u003e. What it does publish is a storage figure: low and medium viscosity types — grade G is one — retain on average \u003cstrong\u003e97 % of their original viscosity after three years\u003c\/strong\u003e at room temperature and with frequent exposure to air. \u003cstrong\u003eIt is worth dating the container on the day it is opened.\u003c\/strong\u003e\u003c\/li\u003e\n\u003cli\u003eIdentification: off-white odourless powder · \u003cstrong\u003eviscosity 150-400 mPa·s at 2 % in water at 25 °C\u003c\/strong\u003e · pH 5.0-8.5 at 2 % · molecular weight 370,000 (manufacturer's data) · CAS no. 9004-64-2.\u003c\/li\u003e\n\u003cli\u003e\u003cstrong\u003eNot classified as hazardous\u003c\/strong\u003e under Regulation (EC) 1272\/2008. Like any fine organic powder, it is \u003cstrong\u003ecombustible in suspension\u003c\/strong\u003e: handle without raising a dust cloud, away from ignition sources and with the container tightly closed. Clear up spills — the wetted product makes the floor slippery.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cem\u003eKlucel® is a trademark of Ashland (formerly Hercules), the manufacturer of the polymer. This 500 g container is distributed by C.T.S.\u003c\/em\u003e\u003c\/p\u003e\n\n\u003cp\u003e\u003cstrong\u003eAlso in the catalogue:\u003c\/strong\u003e \u003ca href=\"\/en\/products\/acido-citrico-99-5-1-kg\"\u003ecitric acid 99.5 % (1 kg)\u003c\/a\u003e is one of the cleaning acids that this thickener holds at constant viscosity within its pH range. \u003cstrong\u003eThe criterion for Klucel® G is the solvent and the type of work:\u003c\/strong\u003e it is chosen when the treatment has to be done without introducing water, when an alcohol or an acid has to be thickened, and to consolidate or adhere without asking it to bear mechanical load. The catalogue holds other conservation adhesives and consolidants with their own pages, among them \u003ca href=\"\/en\/products\/aquazol-200-1-kg\"\u003eAquazol® 200 (1 kg)\u003c\/a\u003e. If you are unsure between them for a particular case, write to us and we will look at it together.\u003c\/p\u003e\n\n\u003ch3\u003eFrequently asked questions\u003c\/h3\u003e\n\u003cdiv class=\"innv-faq\"\u003e\n\u003cdetails\u003e\u003csummary\u003eIf I work with isopropanol, 95 % or 99 %?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003e\u003cstrong\u003eThe 95 %, and it is counter-intuitive.\u003c\/strong\u003e With grade G, 95 % isopropanol gives a \u003cstrong\u003eclear and smooth\u003c\/strong\u003e solution; the 99 % gives it \u003cstrong\u003emoderately grainy and hazy\u003c\/strong\u003e. It is not that the 99 % fails to dissolve: it is a borderline solvent for this grade. The reason is the residual water in the 95 %, which acts as a co-solvent. If you only have isopropanol of the highest purity, the manufacturer itself gives the fix: adding 5 to 15 % of water, methanol or ethanol greatly improves the quality of the solution. The manufacturer's solvent table was measured precisely on grade G and at 2 %, which is the working concentration.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eWhat concentration is it used at?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003eIt depends on the use, and there is no single figure. \u003cstrong\u003eAs a consolidant in ethanol\u003c\/strong\u003e, what the conservation literature documents is use between \u003cstrong\u003e0.5 and 5 %\u003c\/strong\u003e, and the recommendation is the lowest concentration that solves the problem, with \u003cstrong\u003e1-2 % as the starting point\u003c\/strong\u003e: the lower it is, the smaller the risk of discolouration or of a visible change in appearance. \u003cstrong\u003eAs an adhesive and for adhering on paper, 1-2 %.\u003c\/strong\u003e For preparing gels we give no figure, because there is no manufacturer source that supports one for that particular use — tell us the case and we will work it out with you. (As a reference for what the field \u003cem\u003ereports\u003c\/em\u003e, which is not the same as a recommendation: a survey of paper and textile conservators records uses from 0.5 to 10 % in ethanol, without separating grades G and E.)\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow do I prepare it without lumps?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003eIt hydrates slowly and the outer gel layer stops the interior from getting wet. The manufacturer's method is \u003cstrong\u003epre-suspension\u003c\/strong\u003e: add the dry powder to \u003cstrong\u003esix times or more its weight of hot water at 50-60 °C\u003c\/strong\u003e — without going above 60 —, where the powder wets but does not dissolve; then pour that suspension into the cold water and stir for ten minutes or more. Violent agitation is not needed, and is in fact counterproductive: it drags in air and makes foam. If the solution comes out slightly hazy, that does not mean the product has gone off: it contains \u003cstrong\u003esilicon dioxide as an anti-caking agent\u003c\/strong\u003e and the manufacturer warns that this can add a slight haze.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eCan I heat the water so it dissolves faster? Mine has turned milky.\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003eIn water, no: it achieves the opposite. \u003cstrong\u003eAbove 45 °C it is insoluble\u003c\/strong\u003e, and between 40 and 45 °C it \u003cstrong\u003eprecipitates\u003c\/strong\u003e — it does not form a gel. If it has been heated and has turned milky, do not throw it away: precipitation is completely reversible and on cooling below 40 °C with stirring it redissolves, recovering the original viscosity. \u003cstrong\u003eIn organic solvents it is the other way round:\u003c\/strong\u003e heat speeds up dissolution and nothing precipitates. And a solution with 45 % ethanol by volume can be taken to the boil without precipitating.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eDoes it yellow over time?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003e\u003cstrong\u003eIt has been used in paper, bookbinding and leather conservation for more than fifty years with no reports of significant discolouration.\u003c\/strong\u003e In its favour, and measured: it forms no peroxides, its photochemical stability against visible light and near ultraviolet is excellent, and on ageing it does not become insoluble — it remains redissolvable. \u003cstrong\u003eThe limit, unvarnished:\u003c\/strong\u003e among the cellulose ethers it is not the most thermally stable. The Getty classified it in 1990 as thermally \u003cstrong\u003eunstable\u003c\/strong\u003e, and in chain scission grade G came behind carboxymethyl cellulose and methylcellulose. \u003cstrong\u003eAnd the condition that defuses that limit is set by the very source that classified it:\u003c\/strong\u003e applied as a size at 1 or 2 % concentration, discolouration, if it occurs at all, is barely perceptible. At low concentration and in a thin layer, which is how it is used, the practical problem disappears.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eDoes it make any difference to prepare it in water or in alcohol?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003eIn the available accelerated ageing tests \u003cstrong\u003eat 90 °C\u003c\/strong\u003e no difference in yellowing was detected between preparing it in water and in ethanol. The classic measurement was made on Whatman paper after \u003cstrong\u003e731 hours at 90 °C\u003c\/strong\u003e, \u003cstrong\u003enot at use temperature\u003c\/strong\u003e — no source has tested this material at room temperature. The 2021 study finds a difference only at 110 °C, and its own authors consider that temperature too high for this test.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eIs it really reversible?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003e\u003cstrong\u003eIt redissolves in its own solvent\u003c\/strong\u003e, including after ageing. The degradation mechanism is chain scission, not cross-linking, and the conservation sources agree that it remains soluble after artificial ageing. Two qualifications: \u003cstrong\u003eon degraded leather water is not an option\u003c\/strong\u003e — it darkens the leather irreversibly —, so removal is planned with the alcohol it was applied in; and if it is mixed with resins that react with its free hydroxyl groups, the film may become insoluble.\u003c\/div\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eYou have another Klucel G page. How do they differ?\u003c\/summary\u003e\u003cdiv class=\"innv-faq__a\"\u003e\u003cstrong\u003eIt is the same material:\u003c\/strong\u003e hydroxypropyl cellulose grade G, CAS number 9004-64-2 and the same original manufacturer, Ashland. There is no difference in quality between one and the other. What changes is the \u003cstrong\u003epack size and the lead time\u003c\/strong\u003e: this is the \u003cstrong\u003e500 g one, in stock\u003c\/strong\u003e; the page for \u003ca href=\"\/en\/products\/klucel-g-hidroxipropilcelulosa-conservacion-kremer\"\u003eKlucel™ G from Kremer Pigmente\u003c\/a\u003e offers the sizes this one does not — \u003cstrong\u003e100 g\u003c\/strong\u003e for a single treatment and \u003cstrong\u003e1 kg\u003c\/strong\u003e for the studio —, to order and with an estimated delivery of 1 to 2 weeks.\u003c\/div\u003e\u003c\/details\u003e\n\u003c\/div\u003e\n\n\u003cp\u003e\u003cstrong\u003eAny questions?\u003c\/strong\u003e Write to us on \u003ca href=\"https:\/\/wa.me\/34614504565\" target=\"_blank\" rel=\"noopener\"\u003eWhatsApp\u003c\/a\u003e, visit \u003ca href=\"https:\/\/innovart.art\"\u003einnovart.art\u003c\/a\u003e or email us at \u003ca href=\"mailto:info@innovart.art\"\u003einfo@innovart.art\u003c\/a\u003e and we will advise you.\u003c\/p\u003e\n\n\u003cstyle\u003e.innv-faq{margin-top:8px;}.innv-faq details{border:1px solid #e5e2dc;border-radius:8px;margin:0 0 10px;background:#fff;}.innv-faq summary{cursor:pointer;list-style:none;padding:14px 46px 14px 16px;position:relative;font-weight:700;}.innv-faq summary::-webkit-details-marker{display:none;}.innv-faq summary::after{content:'+';position:absolute;right:16px;top:50%;transform:translateY(-50%);font-size:1.4em;line-height:1;color:#00494f;}.innv-faq details[open] summary::after{content:'\\2013';}.innv-faq details[open] summary{border-bottom:1px solid #efece6;}.innv-faq summary:hover{background:#faf8f5;}.innv-faq__a{padding:12px 16px 16px;margin:0;}\u003c\/style\u003e","brand":"CTS","offers":[{"title":"Default Title","offer_id":53793086505307,"sku":null,"price":66.61,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0954\/8441\/2251\/files\/klucel-g-500-g.jpg?v=1786822288","url":"https:\/\/innovart.art\/en\/products\/klucel-g-500-g","provider":"Innovart","version":"1.0","type":"link"}