# Melamine foam
**Melamine foam** is a flexible, open-cell foam made from melamine-formaldehyde resin, a thermoset polymer, best known as acoustic absorption panels, thermal insulation, and the abrasive "magic eraser" cleaning sponge. Its commercial archetype is BASF's Basotect®, and the material combines three properties that rarely coexist in one foam: high sound absorption, intrinsic flame resistance without added flame retardants, and very low weight.
| Key fact | Detail |
|---|---|
| Composition | Flexible open-cell foam of melamine-formaldehyde resin, a thermoset (duroplastic) material with a three-dimensional network of slender, easily flexed filaments[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect) • [2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) |
| Density | 9 g/l for standard Basotect®; the UL grade weighs 30% less[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) |
| Temperature range | Retains flexibility at -200°C and resists application temperatures up to 240°C; thermal conductivity below 0.035 W/(m·K)[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) |
| Fire behavior | Chars without melting, burning droplets, or afterglow; flame resistance comes from the resin's high nitrogen content, with no added flame retardants; B1 classification per DIN 4102 in Germany[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect) |
| Acoustic performance | Absorption coefficient close to 1 above 1000 Hz at 5 cm thickness; porosity about 0.99 and flow resistivity on the order of 10,000 Pa·s/m²[3](https://acoustics.org/pressroom/httpdocs/155th/leroy.htm) • [4](https://doc.comsol.com/6.3/doc/com.comsol.help.models.aco.porous_absorber/porous_absorber.html) |
| Cell structure | Open cells with short hexagonal struts; cell diameters of about 100–200 μm (Illtec) and 150–300 μm (Basotect TG)[5](https://www.sciencedirect.com/science/article/abs/pii/S0003682X08001497) |
| Cleaning use | Melamine sponges abrade like very soft sandpaper; wear releases poly(melamine-formaldehyde) microplastic fibers at about 6.5 million fibers per gram of material lost[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) • [6](https://pubmed.ncbi.nlm.nih.gov/38843113/) |
## Structure and chemistry
The foam is produced by foaming and curing melamine-formaldehyde resin, with the cross-linking of the resin forming an interconnected three-dimensional network of open cells[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect) • [7](https://www.sciencedirect.com/science/article/pii/S1226086X22006955). Microscopy shows cells without walls, built from short hexagonal struts a few micrometers across; in acoustic modeling these struts are treated as "fibre equivalents" with a diameter slightly smaller than that of a 7 μm glass fiber[5](https://www.sciencedirect.com/science/article/abs/pii/S0003682X08001497). The open-cell structure gives the material a very high porosity, about 0.99 of the volume being air[4](https://doc.comsol.com/6.3/doc/com.comsol.help.models.aco.porous_absorber/porous_absorber.html).
Because the resin is highly cross-linked, the foam is resistant to all organic solvents; resistance to acids and alkalis depends on temperature, exposure time, and concentration and must be checked for the specific application[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect). The melamine resin also absorbs moisture, so the water content of the foam, and with it its dimensions, changes with ambient humidity, a behavior the manufacturer compares to wood, concrete, and clay tiles and which must be allowed for in processing[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect).
## Acoustic behavior
Sound waves entering the open-cell surface are not reflected as an echo but penetrate the cell structure, where viscous friction and thermal conduction in the narrow pores dissipate the sound energy as heat[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect) • [4](https://doc.comsol.com/6.3/doc/com.comsol.help.models.aco.porous_absorber/porous_absorber.html). The material is one of the most effective passive absorbers: a 5 cm layer reaches an absorption coefficient close to 1 at frequencies above 1000 Hz[3](https://acoustics.org/pressroom/httpdocs/155th/leroy.htm). Performance at low frequencies is limited by thickness; in one comparative study, a 30 mm melamine foam panel had a weighted random-incidence absorption coefficient of 0.35, lower than 50 mm polyurethane foam (0.60) and 50 mm mineral wool (0.80), and adding an air-permeable wool covering raised the melamine foam's value to 0.65[8](https://vibsys.put.poznan.pl/_journal/2025-36-2/articles/vps_2025207.pdf). Heavier backing layers are a standard way to improve low-frequency absorption[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect).
The acoustic behavior is described by poroelastic parameters including flow resistivity, tortuosity, and viscous and thermal characteristic lengths; published model values for melamine foam include a flow resistivity of 10,500 Pa·s/m², a tortuosity factor of 1.0059, and viscous and thermal characteristic lengths of 240 μm and 470 μm[4](https://doc.comsol.com/6.3/doc/com.comsol.help.models.aco.porous_absorber/porous_absorber.html). Compression of the foam changes these non-acoustical parameters, which is exploited when the material is fitted into constrained spaces[5](https://www.sciencedirect.com/science/article/abs/pii/S0003682X08001497).
## Thermal insulation and fire behavior
The open-cell structure yields a low thermal conductivity, below 0.035 W/(m·K), useful in hot water tanks, solar water heaters, and HVAC ductwork[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=). The foam stays flexible down to -200°C, which allows insulation of liquefied natural gas tanks, and a dedicated cold-flexible grade, Basotect® C, is specified for durable insulation of liquid oxygen and LNG equipment at temperatures down to -196°C[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) • [1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect).
The fire performance follows from chemistry rather than additives: the high nitrogen content of the melamine resin makes the foam flame-resistant without added flame retardants[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect). As a thermoset it does not melt or drip burning droplets when exposed to flames; it chars, produces little smoke, and shows no afterglow, and in standard fire tests it achieves the highest classification available to organic materials[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect). This profile, together with low weight, explains its use in aircraft cabins, trains, and automobile engine compartments, where it serves both as sound absorber and thermal shield[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect).
A related rigid variant is made by blowing a melamine-formaldehyde resin emulsion with pentane and curing it. Rigid MF foams of 50 to 80 kg/m³ density reach a thermal conductivity of 33–34 mW/(m·K) at atmospheric pressure and 6–7 mW/(m·K) in vacuum, with pore sizes of 150–250 μm, properties targeted at vacuum insulation panel cores[9](https://journals.sagepub.com/doi/10.1177/0021955X21997348).
## Cleaning sponges and microplastic fibers
The same fine, glass-hard cell structure that absorbs sound also makes the foam abrasive: it works like very soft sandpaper, rubbing dirt off tiles, glass ceramic, and stained wallpaper when moistened, without chemical cleaning agents[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=). Consumer versions are sold as "magic erasers."
This mechanism has an environmental cost. A 2024 study in *Environmental Science & Technology* abraded melamine cleaning sponges against metal surfaces of varying roughness and found that wear releases poly(melamine-formaldehyde) microplastic fibers, 10–405 μm long, formed by deformation and fracture of the cell struts aided by friction-induced polymer decomposition[6](https://pubmed.ncbi.nlm.nih.gov/38843113/). Fiber production rose with surface roughness and strut density, and the measured wear rate of 6.5 million fibers per gram led the authors to estimate a global emission on the order of 4.9 trillion microplastic fibers from sponge consumption[6](https://pubmed.ncbi.nlm.nih.gov/38843113/).
## Grades and processing
Basotect® is supplied in blocks of standard dimensions (2500 × 1250 × 500 mm) that fabricators cut, stamp, and press into shaped parts; the range includes grades for visible architectural panels (B), a light-gray soil-resistant variant (G+), a thermoformable dark grade for automotive parts (TG), a highly elastic grade for rail and construction (UF+), an ultralight grade for aviation (UL), and a consumer cleaning grade (W) tested to Japanese Law 112 for formaldehyde and certified to STANDARD 100 by OEKO-TEX®[2](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=) • [1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect). Sections can be thermoformed above 200°C, hydrophobed with silicone emulsions, or made water- and oil-repellent in one step with fluorocarbon resins[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect). Cutting and sawing generate dust that should be removed by vacuum at the cutting site; because the material is an open-cell foam rather than a fiber product, the manufacturer states it is not associated with fiber-release irritation[1](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect).
## References
1. [Basotect® (Melamine resin foam), BASF Performance Polymers](https://plastics-rubber.basf.com/global/en/performance_polymers/products/basotect)
2. [Basotect® – The versatile melamine resin foam, BASF brochure (PDF)](https://download.basf.com/p1/8a8081c57fd4b609017fd663ae923c39/en/Basotect%3Csup%3E%C2%AE%3Csup%3E_%E2%80%92_The_Versatile_Melamine_Resin_Foam_Brochure_English.pdf?view=)
3. ["Smart foams" for enhancing acoustic absorption, Acoustics.org (155th Meeting, 2008)](https://acoustics.org/pressroom/httpdocs/155th/leroy.htm)
4. [Porous Absorber model, COMSOL 6.3 documentation](https://doc.comsol.com/6.3/doc/com.comsol.help.models.aco.porous_absorber/porous_absorber.html)
5. [Investigation of non-acoustical parameters of compressed melamine foam materials, Applied Acoustics](https://www.sciencedirect.com/science/article/abs/pii/S0003682X08001497)
6. [Su, Yu, et al. (2024). Mechanochemical Formation of Poly(melamine-formaldehyde) Microplastic Fibers During Abrasion of Cleaning Sponges. Environmental Science & Technology.](https://pubmed.ncbi.nlm.nih.gov/38843113/)
7. [Toughening of melamine–formaldehyde foams and advanced applications based on functional design, Polymer](https://www.sciencedirect.com/science/article/pii/S1226086X22006955)
8. [Effect of coverage on the acoustic performance of selected porous and fibrous materials, Vibrations in Physical Systems, 2025, 36(2)](https://vibsys.put.poznan.pl/_journal/2025-36-2/articles/vps_2025207.pdf)
9. [Kavšek, M., et al. (2022). Melamine-formaldehyde rigid foams – Manufacturing and their thermal insulation properties. Journal of Cellular Plastics, 58(1).](https://journals.sagepub.com/doi/10.1177/0021955X21997348)
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*Topic: Encyclopedia › Physical world and mathematics › Physics › Classical physics › Waves and optics › Wave phenomena and acoustics › Acoustics › Applied and engineering acoustics › Acoustic materials and treatments*
*Initially written Sep 17, 2026 · Reviewed: Sep 17, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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