Martin · Guitar Strings
Martin MSPLUS4100 SP+ Coated Phosphor Bronze Light Acoustic Guitar Strings
Lower concern; acoustic guitar strings with no known PFAS use, but Martin does not disclose coating details.
Martin's MSPLUS4100 SP+ strings use phosphor bronze wire with an undisclosed proprietary coating. Acoustic guitar strings are not a typical PFAS application, coatings are designed for corrosion resistance and tone, not water-repellency or nonstick properties.
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Phosphor bronze wire with SP+ coating (Martin proprietary)
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Category baseline
other is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
Safe base material
Made from a material with no inherent PFAS use (ceramic, mineral, or natural fiber).
The full breakdown
What it's made of and why it matters
Martin MSPLUS4100 strings use phosphor bronze wire, a copper-tin-phosphorus alloy chosen for acoustic brightness and durability. The SP+ coating is Martin's proprietary treatment applied to the wound strings to extend lifespan and reduce finger noise. Phosphor bronze itself is non-toxic; the coating chemistry remains undisclosed but is standard industry practice for this product class and not known to leach hazardous substances during normal use.
The brand's record and disclosure
Martin Guitars is a long-established American manufacturer with no recorded safety recalls or contamination incidents involving their string products. The company does not publicly disclose the detailed chemical composition of its SP+ coating, which is typical for guitar string manufacturers protecting proprietary formulations. Martin has made no public PFAS commitments or sustainability certifications specific to strings, reflecting broader industry silence on this issue.
How it compares in its category
Phosphor bronze light-gauge strings are among the safest options in acoustic guitar strings; they occupy a middle ground between cheaper bronze (less durable) and pricier coated variants from Elixir or D'Addario that use polyester-based coatings. Martin's SP+ coating is less marketed than competitor coatings but follows the same general principle of reducing corrosion and extend playability. No comparative hazard data exists because string products are not heavily regulated or tested for consumer safety.
If you buy it
Store strings in a cool, dry place to prevent oxidation of the bronze; coating integrity is not affected by normal playing conditions. Replace strings when they sound dull, feel rough, or visibly corrode (rust-colored deposits), typically every 1-3 months depending on playing frequency. Wash your hands before playing to minimize sweat and dirt transfer, which accelerates coating wear and corrosion. No special handling or safety precautions are required beyond standard string care.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Metal leaching from phosphor bronze core
Phosphor bronze strings do not contact food or drinking water during normal use. The copper and tin in the alloy are not absorbed through skin contact or ingestion from handling strings.
Coating degradation and particle shedding
The SP+ coating may gradually wear with playing, but shed particles are microscopic and are not ingested or inhaled in meaningful quantities. Martin does not disclose coating material, so specific toxicity cannot be assessed.
Formaldehyde or other preservatives in coating
No evidence exists that Martin uses formaldehyde-releasing compounds in string coatings. Acoustic string coatings typically rely on polymeric or wax-based protection, not chemical preservatives.
Heavy metals in phosphor bronze alloy
Phosphor bronze is a regulated alloy composed of copper, tin, and phosphorus; lead and cadmium are not intentionally added. The alloy is food-grade safe for contact with human skin and mouth.
Volatile organic compound (VOC) off-gassing from coating
Strings are a minor source of VOC exposure compared to instrument bodies or amplifiers. No off-gassing complaints or incidents are recorded for Martin strings, and the coating is applied in small quantities per string.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 72% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Guitar Strings
Martin
Retro Acoustic Guitar Strings
Phosphor bronze, stainless steel, nylon wound
Lower concern, acoustic guitar strings typically use established metals and nylon without water-repellent coating or nonstick coatings.
✓Bare metal or glass, no coating at all
Acoustic360
Ernie Ball Everlast Acoustic Guitar Strings
Phosphor bronze/stainless steel wound on steel core
Lower PFAS concern, acoustic guitar strings use standard metal materials with no known fluorochemical treatments.
✓Bare metal or glass, no coating at all
Dean Markley
Electric Guitar Strings
Steel alloy strings (nickel-plated or stainless steel core)
Lower PFAS concern, steel strings lack typical PFAS applications, but no brand disclosure exists.
✓Bare metal or glass, no coating at all
More guitar strings grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.