If you work in conservation-restoration, Paraloid B-72 is probably the consolidant you've held most often.
In this guide, we review what it is exactly, how it's prepared, how it's applied step-by-step, common mistakes, and in which situations it should be chosen over other options.
What is Paraloid B-72?
Paraloid B-72 is an acrylic copolymer of ethyl methacrylate and methyl acrylate, with a predominance of ethyl methacrylate. It is presented as translucent granules or beads that dissolve in organic solvents to obtain consolidant or adhesive solutions. This composition gives it chemical stability, transparency, and long-term reversibility.
Properties that make it essential
- Long-term chemical stability: it does not yellow or become brittle over time. Accelerated aging studies confirm its stable behavior for decades.
- Total reversibility: it dissolves easily in acetone, ethanol, or mixtures of both, even after a long time.
- No water: unlike aqueous dispersion consolidants, B-72 in solvent does not add moisture to the substrate, which is critical when working on easel paintings or hygroscopic supports.
Common concentrations
| Concentration | Application |
|---|---|
| 2-3% | Fixative / pre-consolidation of powdery layers |
| 5% | Standard consolidation of pictorial layers |
| 10% | Consolidation of porous materials |
| 15-30% | Adhesive for joining fragments (ceramics, archaeology) |
At Innovart, we supply Paraloid B-72 in four formats: 100 g, 500 g, 1 kg, and 10 kg. The small containers exist precisely so you don't have to buy a kilo of resin when you only need it for a specific intervention.
Recommended solvents
- Acetone: dissolves B-72 quickly. It is the most common solvent, but its rapid evaporation can promote whitening in humid environments; in such cases, mixtures with ethanol or slower-evaporating solvents are used to control drying.
- Ethanol: slower, longer working time.
- Acetone/ethanol mixture (1:1): balance between speed and working time. Widely used in laboratories.
How to prepare and apply Paraloid B-72 step-by-step
Preparation is simple, but the order matters to avoid lumps and obtain a homogeneous solution.
- Calculate the weight/volume (w/v) concentration. A 5% solution is 5 g of granules per 100 ml of solvent. Weigh the granules before starting.
- Add the granules to the solvent, not the other way around. Pour the solvent into the container and drop the beads in. If you do the opposite, the granules tend to clump at the bottom.
- Allow to dissolve without stirring initially. B-72 swells and dissolves on its own within a few hours (sometimes it's best to leave it overnight). Gentle stirring at the end helps to homogenize; stirring from the start generates foam and microbubbles that remain in the film.
- Protect yourself and ventilate. Acetone and ethanol are volatile and flammable: work with local extraction, nitrile gloves, and away from heat sources. And with acetone there is a detail almost no one keeps in mind: type A organic vapour filters are defined for solvents with a boiling point above 65 °C, and acetone boils at around 56. With acetone, the protection is extraction, not the respirator. With ethanol (78 °C), a type A filter is indeed the right equipment.
- Apply as appropriate. By impregnation with a brush or by dripping for consolidation; with a syringe for punctual adhesion of fragments. Apply thin layers and allow the solvent to evaporate between coats instead of applying a single thick layer.
- Control the finish. At high concentrations or with excessive product, a surface sheen may remain. If this occurs, it can be smoothed out with a pass of the solvent.
Common mistakes when using Paraloid B-72
- Concentration too high for pre-consolidation. In powdery layers, a highly concentrated solution stays on the surface and forms a film without penetrating. For fixing, reduce to 2-3%.
- Applying to a damp substrate. B-72 in solvent is not compatible with water: if the support is damp, consolidation fails. Here, other options are more suitable (see next section).
- A single thick layer. Solvent trapped under a thick film takes a long time to evaporate and can cause whitening. Several thin layers are better.
- Confusing the granules with a ready-to-use product. B-72 is sold in beads precisely so that each restorer can prepare the concentration and solvent that their intervention requires.
When to choose Paraloid B-72 over other options
B-72 is the first choice when the substrate cannot tolerate water and maximum reversibility is needed. When the substrate is damp or does not accept organic solvents, aqueous dispersion alternatives such as Lascaux 498-HV or Primal AC-33 may be more suitable.
Frequently asked questions about Paraloid B-72
How long does a prepared Paraloid B-72 solution last?
Stored in a tightly closed container at room temperature, the solution remains usable for a long time. If the solvent partially evaporates and the solution thickens, simply readjust by adding more solvent.
Is it reversible once dry?
Yes. One of its main advantages is that it redissolves with acetone or ethanol even after a long time, allowing for removal or re-intervention of the consolidation. This is why it is a reference material under the criterion of reversibility in conservation-restoration.
Does it work as an adhesive in addition to a consolidant?
Yes. At high concentrations (around 15-30%), it functions as an adhesive, commonly used for joining ceramic and archaeological fragments. For consolidation, much lower concentrations are used.
Which solvent should I choose, acetone or ethanol?
It depends on the working time you need. Acetone evaporates very quickly (useful when you want it to dry soon); ethanol gives more handling time. The 1:1 mixture is a widely used equilibrium point.
In what formats is Paraloid B-72 sold?
At Innovart, we supply it in 100 g, 500 g, 1 kg, and 10 kg. For workshops with continuous work, the kilo is the usual format; the small containers prevent resin from sitting unused if you only need it for a specific intervention.
Where to buy Paraloid B-72 in Spain
At Innovart, we work with curated conservation and restoration materials and provide real technical advice: if you have a specific intervention and don't know what concentration or solvent is suitable, you can ask us before buying.
→ View Paraloid B-72 at Innovart (from 100 g to 10 kg)
→ View all adhesives and consolidants for restoration
Still have doubts about what concentration to use in your case? Write to us at info@innovart.art and we will help you choose. This is not a sales form.