Saved to your guest loadout. Sign up to also save to your Cabinet (consumables) or Kit (tools you own).
As an Amazon Associate and affiliate partner, CarCareTruth earns from qualifying purchases. Full disclosure
Prices may varyFrom the Safety Data Sheet
Full SDS ↗ (rev. 2023-06-09)GHS hazard codes are quoted from the manufacturer’s Safety Data Sheet. PPE tiers below translate those codes and the listed ingredient chemistry; they are not CarCareTruth recommendations.
EyesRequiredMfr. SDS §8 · 29 CFR 1910.133(a)(1) · GHS H318SkinRequiredMfr. SDS §8 · 29 CFR 1910.132 · GHS H314LungsSituationalMfr. SDS §8Ventilation—No PPE in published sourcesShow details for all categories ▾Hide details ▴
From the manufacturer’s Safety Data Sheet, Section 8
“H318 (serious eye damage Cat 1) and H314 (skin corrosion 1B) both present in SDS §2. GHS05 corrosion pictogram confirmed. Full splash-proof goggles or face shield per SDS §8.5.3.”
— Optimum
U.S. regulatory standard
29 CFR 1910.133(a)(1); 1910.151(c)
“The employer shall ensure that each affected employee uses appropriate eye or face protection when exposed to eye or face hazards from… liquid chemicals, acids or caustic liquids…”
ANSI Z87.1 (chemical splash protection — incorporated via §1910.6)
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
From the manufacturer’s Safety Data Sheet, Section 8
“H314 (skin corrosion Cat 1B) in SDS §2. SDS §8.5.2 specifies Viton gloves for full and splash contact. Phosphoric acid at 10–20% causes documented skin burns on contact.”
— Optimum
U.S. regulatory standard
29 CFR 1910.132; 1910.133; 1910.138; 1910.151(c)
“Where the eyes or body of any person may be exposed to injurious corrosive materials, suitable facilities for quick drenching or flushing of the eyes and body shall be provided within the work area for immediate emergency use.”
ANSI Z87.1 (eye/face — incorporated via §1910.6)
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
From the manufacturer’s Safety Data Sheet, Section 8
“H336 (STOT SE3 — drowsiness/dizziness) in SDS §2 from IPA (1–2%) and phosphoric acid vapors. SDS §8.5.1 invokes respirator only 'where risk assessment shows' — generic boilerplate. Pad-application format reduces inhalation pathway vs. spray; situational for enclosed garage use or repeated commercial application.”
— Optimum
CarCareTruth publishes the cited sources verbatim and does not advise what action a user should take. Consult the full SDS before use.
The published Safety Data Sheet for this product does not specify ventilation protection for consumer use.
Workplace context
29 CFR 1910.134(a); 1910.1000
“the primary objective shall be to prevent atmospheric contamination [via] accepted engineering control measures (for example, enclosure or confinement of the operation, general and local ventilation…).”
Triggered by GHS H336 on the SDS.
OSHA standards apply to workplaces. Cited here as the U.S. reference threshold for the underlying hazard class.
PPE tiers translate the manufacturer’s SDS and U.S. regulatory standards. Not professional safety advice. How we report safety.
CarCareTruth's Analysis
Last reviewed May 16, 2026
TL;DR Dissolves hard-water mineral deposits from paint, glass, and chrome via phosphoric acid — no abrasives, no polishing step. DANGER signal word on the SDS: H314 skin corrosion, H318 serious eye damage, Prop 65 for Ethylene Oxide. Viton gloves and eye protection are required by the SDS chemistry. Adequate for typical mineral spotting; 3.8 stars across 75 reviews shows inconsistency on severe scale.
What it is and how it performs
MDR uses phosphoric acid (10–20%) to dissolve bonded mineral scale without abrading painted surfaces. Pour onto a microfiber towel or foam applicator, wipe onto the surface, allow one minute of dwell, wipe away residue, and rinse. A repeat pass handles stubborn deposits. Reviews are mixed — typical hard-water spotting on coated paint responds well; heavy or long-standing scale may need multiple applications.
Who should buy this — and who should skip it
Right for owners dealing with mineral scale on painted panels, glass, or chrome that survives normal washing. Optimum markets MDR as multi-surface and paint-safe — it does not require avoiding painted surfaces. Skip it for fresh, light spotting from a single rain event — a standard wash suffices. The DANGER-class chemistry and 3.8-star average suggest buyers needing reliable single-pass results on severe etching should compare alternatives.
Safety and environmental impact
DANGER signal word: H314 (skin corrosion Cat 1B), H318 (serious eye damage Cat 1), H302 (harmful if swallowed), H336 (drowsiness/dizziness). Viton gloves and eye protection are required by the SDS chemistry. SDS §15 carries a California Prop 65 warning for Ethylene Oxide — carcinogen and reproductive toxin, a trace residual in the ethoxylated surfactants. VOC is 15 g/L (SDS §9); no mixture-level aquatic toxicity code at product level. Rinse to sanitary sewer.
Frequently asked questions
Is Optimum MDR safe to use on painted car surfaces?▾
The brand explicitly markets MDR as paint-safe and non-abrasive — the Amazon listing states 'Car Paint Safe' and 'will break down and dissolve contaminants leaving the surface clean and smooth without affecting or removing paint.' Despite this claim, the SDS shows a DANGER signal word with skin corrosion (H314) at concentrate strength. Apply as directed using an applicator pad and do not allow the product to pool or sit on painted surfaces for longer than the labeled dwell time. Spot-test on a discreet area first.
What type of acid is in Optimum MDR?▾
Phosphoric acid (10–20%) is the primary active ingredient, per SDS Section 3. This is confirmed on the SDS publicly hosted by Optimum Polymer Technologies. Phosphoric acid dissolves calcium, magnesium, and silica-based mineral deposits by chemical reaction.
Does Optimum MDR require a Prop 65 warning?▾
Yes. SDS Section 15 states an explicit California Proposition 65 warning for Ethylene Oxide (CAS 75-21-8), a carcinogen and reproductive toxin. Ethylene Oxide is a trace synthesis residual in the ethoxylated amine surfactants used in the formula, not a performance ingredient.
Is Optimum MDR safe for window tint?▾
The brand does not make a tint-safe claim on the product page or SDS. The phosphoric acid formula at high working strength could potentially affect some aftermarket tint films. No community data confirming safe use on window tint films was found. Avoid contact with aftermarket tint films and verify with a spot test before use near tinted windows.
Weekly pick
One product, one safety verdict, every week. No spam.
More from Optimum
More in Glass Water Spot Remover
Gtechniq
W9 Water Spot Remover
CCT 7.0 · DecentHealth 8.5
McKee's 37
FAST Water Spot Remover
CCT 6.8 · DecentHealth 8.5
Chemical Guys
Heavy Duty Water Spot Remover
CCT 6.1 · DecentHealth 1.8
As an Amazon Associate and affiliate partner, CarCareTruth earns from qualifying purchases. Full disclosure
Community
0 postsShare how you use this product
Drop a quick comment or post a full review with photos and a star rating.
Sign in to postNew here? Create a free account.