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Potassium Hydroxide Chemical Resistance

Resistance ratings for 24 plastics, elastomers and metals at 20 °C and 50 °C. Listed at 5 concentrations, because the rating depends on it.

At a glance

Based on the row for 50 %, 20 °C.

Rated A, very good resistance
PTFE, HDPE, PP, PVC Rigid, EPDM, SS 316, SS 304, LDPE, FEP, ECTFE/ETFE, Nylon (PA), PVC Flexible, Polysulfone, PMP, SAN (15)
Rated B, good resistance
Polystyrene (1)
Rated C, limited resistance
PVDF, NBR, Acetal (POM) (3)
Rated D, not resistant
Viton (FPM), Aluminium, Polycarbonate, PETG (4)
No data in the source
Silicone
Rated lower at 50 °C than at 20 °C
PVC Rigid (A → C), NBR (C → D), Nylon (PA) (A → C), SAN (A → C)
Rating changes with concentration (20 °C)
PVDF: A (1 %), C (50 %); Viton (FPM): A (1 %), D (10 %); Acetal (POM): A (1 %), C (30 %); Polycarbonate: C (1 %), D (10 %); Polystyrene: A (30 %), B (1 %)

Based on the row for 50 %, 20 °C.

Rating profile by material family

Potassium Hydroxide: Rating profile by material familyThermoplastics: 9 A, 1 B, 1 C, 2 D. Fluoropolymers: 3 A, 1 C. Elastomers: 1 A, 1 C, 1 D, 1 no data. Metals: 2 A, 1 D.Thermoplastics (13)Thermoplastics: 9 × A, very good resistance (HDPE, LDPE, PP, PVC Rigid, PVC Flexible, PMP, SAN, Nylon (PA), Polysulfone)A 9Thermoplastics: 1 × B, good resistance (Polystyrene)Thermoplastics: 1 × C, limited resistance (Acetal (POM))Thermoplastics: 2 × D, not resistant (Polycarbonate, PETG)D 2Fluoropolymers (4)Fluoropolymers: 3 × A, very good resistance (PTFE, FEP, ECTFE/ETFE)A 3Fluoropolymers: 1 × C, limited resistance (PVDF)C 1Elastomers (4)Elastomers: 1 × A, very good resistance (EPDM)A 1Elastomers: 1 × C, limited resistance (NBR)C 1Elastomers: 1 × D, not resistant (Viton (FPM))D 1Elastomers: 1 × no data (Silicone)– 1Metals (3)Metals: 2 × A, very good resistance (SS 316, SS 304)A 2Metals: 1 × D, not resistant (Aluminium)D 1
A very good resistanceB good resistanceC limited resistanceD not resistantno data
Number of materials in each family with each rating at 20 °C.

Effect of temperature, 20 °C to 50 °C

Potassium Hydroxide: Effect of temperature, 20 °C to 50 °CPVC Rigid A → C; SAN A → C; Nylon (PA) A → C; NBR C → D.ABCDPVC Rigid: A at 20 °C, C at 50 °CPVC RigidSAN: A at 20 °C, C at 50 °CSANNylon (PA): A at 20 °C, C at 50 °CNylon (PA)NBR: C at 20 °C, D at 50 °CNBR
20 °C50 °C
Materials whose rating differs between 20 °C and 50 °C. Materials not shown keep their rating or have no 50 °C value.

Substance

CAS number
1310-58-3
Formula
KHO
Hazard symbols in the source
C (corrosive) (pre-GHS European symbols; check the current safety data sheet)
Concentrations listed
1 %; 10 %; 30 %; 50 %; concentrated
Also listed as
Potassium Hydroxide (Caustic Potash); Potassium hydroxide solution
Name in the source (German)
Kaliumhydroxid

Rating by concentration

Potassium Hydroxide: Rating by concentrationHDPE: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. LDPE: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. PP: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. PVC Rigid: 1 % A, 10 % –, 30 % A→C, 50 % A→C, concentrated A→B. PVC Flexible: 1 % –, 10 % –, 30 % A, 50 % A, concentrated A. PMP: 1 % A, 10 % –, 30 % A, 50 % A, concentrated A. Polystyrene: 1 % B, 10 % –, 30 % A, 50 % B, concentrated B. SAN: 1 % –, 10 % A, 30 % –, 50 % A→C, concentrated A→C. Polycarbonate: 1 % C→D, 10 % D, 30 % D, 50 % D, concentrated D. PETG: 1 % D*, 10 % D, 30 % D, 50 % D, concentrated D. Acetal (POM): 1 % A, 10 % A, 30 % C*, 50 % C, concentrated C. Nylon (PA): 1 % A, 10 % A, 30 % A→C, 50 % A→C, concentrated A. Polysulfone: 1 % A, 10 % –, 30 % A, 50 % A, concentrated A. PTFE: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. FEP: 1 % A, 10 % A, 30 % –, 50 % A, concentrated A. PVDF: 1 % A, 10 % A, 30 % B*, 50 % C, concentrated C. ECTFE/ETFE: 1 % A, 10 % A, 30 % –, 50 % A, concentrated A. EPDM: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. Viton (FPM): 1 % A→C, 10 % D, 30 % D, 50 % D, concentrated D. NBR: 1 % C, 10 % C, 30 % C, 50 % C→D, concentrated C→D. SS 316: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. SS 304: 1 % A, 10 % A, 30 % A, 50 % A, concentrated A. Aluminium: 1 % D, 10 % D, 30 % D, 50 % D, concentrated D.1 %10 %30 %50 %concent…THERMOPLASTICSHDPEHDPE, 1 %: A at 20 °C, A at 50 °CAHDPE, 10 %: A at 20 °C, A at 50 °CAHDPE, 30 %: A at 20 °C, A at 50 °CAHDPE, 50 %: A at 20 °C, A at 50 °CAHDPE, concentrated: A at 20 °C, A at 50 °CALDPELDPE, 1 %: A at 20 °C, A at 50 °CALDPE, 10 %: A at 20 °C, A at 50 °CALDPE, 30 %: A at 20 °C, A at 50 °CALDPE, 50 %: A at 20 °C, A at 50 °CALDPE, concentrated: A at 20 °C, A at 50 °CAPPPP, 1 %: A at 20 °C, A at 50 °CAPP, 10 %: A at 20 °C, A at 50 °CAPP, 30 %: A at 20 °C, A at 50 °CAPP, 50 %: A at 20 °C, A at 50 °CAPP, concentrated: A at 20 °C, A at 50 °CAPVC RigidPVC Rigid, 1 %: A at 20 °C, A at 50 °CAPVC Rigid, 10 %: no data–PVC Rigid, 30 %: A at 20 °C, C at 50 °CA→CPVC Rigid, 50 %: A at 20 °C, C at 50 °CA→CPVC Rigid, concentrated: A at 20 °C, B at 50 °CA→BPVC FlexiblePVC Flexible, 1 %: no data–PVC Flexible, 10 %: no data–PVC Flexible, 30 %: A at 20 °CAPVC Flexible, 50 %: A at 20 °CAPVC Flexible, concentrated: A at 20 °CAPMPPMP, 1 %: A at 20 °C, A at 50 °CAPMP, 10 %: no data–PMP, 30 %: A at 20 °CAPMP, 50 %: A at 20 °C, A at 50 °CAPMP, concentrated: A at 20 °C, A at 50 °CAPolystyrenePolystyrene, 1 %: B at 20 °C, B at 50 °CBPolystyrene, 10 %: no data–Polystyrene, 30 %: A at 20 °CAPolystyrene, 50 %: B at 20 °C, B at 50 °CBPolystyrene, concentrated: B at 20 °C, B at 50 °CBSANSAN, 1 %: no data–SAN, 10 %: A at 20 °C, A at 50 °CASAN, 30 %: no data–SAN, 50 %: A at 20 °C, C at 50 °CA→CSAN, concentrated: A at 20 °C, C at 50 °CA→CPolycarbonatePolycarbonate, 1 %: C at 20 °C, D at 50 °CC→DPolycarbonate, 10 %: D at 20 °C, D at 50 °CDPolycarbonate, 30 %: D at 20 °C, D at 50 °CDPolycarbonate, 50 %: D at 20 °C, D at 50 °CDPolycarbonate, concentrated: D at 20 °C, D at 50 °CDPETGPETG, 1 %: D at 20 °C (estimate)D*PETG, 10 %: D at 20 °C, D at 50 °CDPETG, 30 %: D at 20 °C, D at 50 °CDPETG, 50 %: D at 20 °C, D at 50 °CDPETG, concentrated: D at 20 °C, D at 50 °CDAcetal (POM)Acetal (POM), 1 %: A at 20 °C, A at 50 °CAAcetal (POM), 10 %: A at 20 °C, A at 50 °CAAcetal (POM), 30 %: C at 20 °C (estimate)C*Acetal (POM), 50 %: C at 20 °CCAcetal (POM), concentrated: C at 20 °CCNylon (PA)Nylon (PA), 1 %: A at 20 °CANylon (PA), 10 %: A at 20 °CANylon (PA), 30 %: A at 20 °C, C at 50 °CA→CNylon (PA), 50 %: A at 20 °C, C at 50 °CA→CNylon (PA), concentrated: A at 20 °CAPolysulfonePolysulfone, 1 %: A at 20 °C, A at 50 °CAPolysulfone, 10 %: no data–Polysulfone, 30 %: A at 20 °CAPolysulfone, 50 %: A at 20 °C, A at 50 °CAPolysulfone, concentrated: A at 20 °C, A at 50 °CAFLUOROPOLYMERSPTFEPTFE, 1 %: A at 20 °C, A at 50 °CAPTFE, 10 %: A at 20 °C, A at 50 °CAPTFE, 30 %: A at 20 °C, A at 50 °CAPTFE, 50 %: A at 20 °C, A at 50 °CAPTFE, concentrated: A at 20 °C, A at 50 °CAFEPFEP, 1 %: A at 20 °C, A at 50 °CAFEP, 10 %: A at 20 °C, A at 50 °CAFEP, 30 %: no data–FEP, 50 %: A at 20 °C, A at 50 °CAFEP, concentrated: A at 20 °C, A at 50 °CAPVDFPVDF, 1 %: A at 20 °C, A at 50 °CAPVDF, 10 %: A at 20 °C, A at 50 °CAPVDF, 30 %: B at 20 °C (estimate)B*PVDF, 50 %: C at 20 °C, C at 50 °CCPVDF, concentrated: C at 20 °C, C at 50 °CCECTFE/ETFEECTFE/ETFE, 1 %: A at 20 °C, A at 50 °CAECTFE/ETFE, 10 %: A at 20 °C, A at 50 °CAECTFE/ETFE, 30 %: no data–ECTFE/ETFE, 50 %: A at 20 °C, A at 50 °CAECTFE/ETFE, concentrated: A at 20 °C, A at 50 °CAELASTOMERSEPDMEPDM, 1 %: A at 20 °CAEPDM, 10 %: A at 20 °CAEPDM, 30 %: A at 20 °CAEPDM, 50 %: A at 20 °CAEPDM, concentrated: A at 20 °CAViton (FPM)Viton (FPM), 1 %: A at 20 °C, C at 50 °CA→CViton (FPM), 10 %: D at 20 °C, D at 50 °CDViton (FPM), 30 %: D at 20 °C, D at 50 °CDViton (FPM), 50 %: D at 20 °C, D at 50 °CDViton (FPM), concentrated: D at 20 °C, D at 50 °CDNBRNBR, 1 %: C at 20 °C, C at 50 °CCNBR, 10 %: C at 20 °C, C at 50 °CCNBR, 30 %: C at 20 °C, C at 50 °CCNBR, 50 %: C at 20 °C, D at 50 °CC→DNBR, concentrated: C at 20 °C, D at 50 °CC→DMETALSSS 316SS 316, 1 %: A at 20 °C, A at 50 °CASS 316, 10 %: A at 20 °C, A at 50 °CASS 316, 30 %: A at 20 °C, A at 50 °CASS 316, 50 %: A at 20 °C, A at 50 °CASS 316, concentrated: A at 20 °C, A at 50 °CASS 304SS 304, 1 %: A at 20 °C, A at 50 °CASS 304, 10 %: A at 20 °C, A at 50 °CASS 304, 30 %: A at 20 °C, A at 50 °CASS 304, 50 %: A at 20 °C, A at 50 °CASS 304, concentrated: A at 20 °C, A at 50 °CAAluminiumAluminium, 1 %: D at 20 °C, D at 50 °CDAluminium, 10 %: D at 20 °C, D at 50 °CDAluminium, 30 %: D at 20 °C, D at 50 °CDAluminium, 50 %: D at 20 °C, D at 50 °CDAluminium, concentrated: D at 20 °C, D at 50 °CD
A very good resistanceB good resistanceC limited resistanceD not resistantno data
Each cell shows the rating at 20 °C. Where the rating at 50 °C differs, it follows the arrow. * marks an estimate in the source.
Show as a table
Material1 %10 %30 %50 %concentrated
Thermoplastics
HDPEAAAAA
LDPEAAAAA
PPAAAAA
PVC RigidA–AAA
PVC Flexible––AAA
PMPA–AAA
PolystyreneB–ABB
SAN–A–AA
PolycarbonateCDDDD
PETGD*DDDD
Acetal (POM)AAC*CC
Nylon (PA)AAAAA
PolysulfoneA–AAA
Fluoropolymers
PTFEAAAAA
FEPAA–AA
PVDFAAB*CC
ECTFE/ETFEAA–AA
Elastomers
EPDMAAAAA
Viton (FPM)ADDDD
NBRCCCCC
Silicone–––––
Metals
SS 316AAAAA
SS 304AAAAA
AluminiumDDDDD

* estimated rating, given in the source without a temperature

Resistance table: Potassium Hydroxide, 1 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PVC RigidAA
PMPAA
PolystyreneBB
PolycarbonateCD
PETGD*–
Acetal (POM)AA
Nylon (PA)A–
PolysulfoneAA
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
ECTFE/ETFEAA
Elastomers
EPDMA–
Viton (FPM)AC
NBRCC
Metals
SS 316AA
SS 304AA
AluminiumDD

* estimated rating, given in the source without a temperature

Not rated in the source, so not in the table: PVC Flexible, SAN, Silicone

Resistance table: Potassium Hydroxide, 10 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
SANAA
PolycarbonateDD
PETGDD
Acetal (POM)AA
Nylon (PA)A–
Fluoropolymers
PTFEAA
FEPAA
PVDFAA
ECTFE/ETFEAA
Elastomers
EPDMA–
Viton (FPM)DD
NBRCC
Metals
SS 316AA
SS 304AA
AluminiumDD

Not rated in the source, so not in the table: PVC Rigid, PVC Flexible, PMP, Polystyrene, Polysulfone, Silicone

Resistance table: Potassium Hydroxide, 30 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PVC RigidAC
PVC FlexibleA–
PMPA–
PolystyreneA–
PolycarbonateDD
PETGDD
Acetal (POM)C*–
Nylon (PA)AC
PolysulfoneA–
Fluoropolymers
PTFEAA
PVDFB*–
Elastomers
EPDMA–
Viton (FPM)DD
NBRCC
Metals
SS 316AA
SS 304AA
AluminiumDD

* estimated rating, given in the source without a temperature

Not rated in the source, so not in the table: SAN, FEP, ECTFE/ETFE, Silicone

Resistance table: Potassium Hydroxide, 50 %

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PVC RigidAC
PVC FlexibleA–
PMPAA
PolystyreneBB
SANAC
PolycarbonateDD
PETGDD
Acetal (POM)C–
Nylon (PA)AC
PolysulfoneAA
Fluoropolymers
PTFEAA
FEPAA
PVDFCC
ECTFE/ETFEAA
Elastomers
EPDMA–
Viton (FPM)DD
NBRCD
Metals
SS 316AA
SS 304AA
AluminiumDD

Not rated in the source, so not in the table: Silicone

Resistance table: Potassium Hydroxide, concentrated

Material20 °C50 °CRemark
Thermoplastics
HDPEAA
LDPEAA
PPAA
PVC RigidAB
PVC FlexibleA–
PMPAA
PolystyreneBB
SANAC
PolycarbonateDD
PETGDD
Acetal (POM)C–
Nylon (PA)A–
PolysulfoneAA
Fluoropolymers
PTFEAA
FEPAA
PVDFCC
ECTFE/ETFEAA
Elastomers
EPDMA–
Viton (FPM)DD
NBRCD
Metals
SS 316AA
SS 304AA
AluminiumDD

Not rated in the source, so not in the table: Silicone

Rating scale

A rating marked * is an estimate in the source, not a test result. An estimate is given as one value without a temperature.

Frequently Asked Questions

Which materials resist Potassium Hydroxide at high concentrations?

The materials with an A rating (resistant) for Potassium Hydroxide at 20 °C are: PTFE, HDPE, PP, PVC Rigid, EPDM, SS 316, SS 304, LDPE. These can generally be used in direct contact.

Which materials should be avoided with Potassium Hydroxide?

Materials rated D (not resistant) for Potassium Hydroxide are: Viton (FPM), Aluminium, Polycarbonate, PETG. These should not be used in contact with Potassium Hydroxide.

Does temperature affect chemical resistance to Potassium Hydroxide?

Yes. 4 of 20 tested materials show a worse rating at 50 °C than at 20 °C for Potassium Hydroxide. Materials affected include: PVC Rigid, NBR, Nylon (PA), SAN.

Is PTFE safe for Potassium Hydroxide?

PTFE is rated A for Potassium Hydroxide at 20 °C. A rating of A means resistant, B means limited resistance, C means partly resistant, and D means not resistant.

Does concentration affect chemical resistance to Potassium Hydroxide?

Yes. Potassium Hydroxide is tested at 5 concentrations (1 %, 10 %, 30 %, 50 %, concentrated). Some materials change their rating depending on the concentration.

About this data

The ratings come from the chemical resistance list published by Bürkle GmbH, which compiled them from raw-material manufacturers’ data. They describe laboratory tests on the raw material at 20 °C and 50 °C.

A finished part also sees pressure, mechanical stress, welds and mixtures that a laboratory test does not. Treat the rating as a first filter and test under your own conditions before relying on it.

Chemicals with a similar resistance profile

Same 20 °C rating on the share of materials shown.

Potassium Cyanide 82 %Silver Nitrate 78 %Sodium Hydroxide (Caustic Soda) 78 %Brake Fluid 75 %Alum (Potassium Aluminum Sulfate) 73 %Tartaric Acid 73 %