Sodium hypochlorite (chlorine bleach)
A powerful oxidising bleach and disinfectant. It is also the substance behind the most common serious household chemical accidents, and must never be mixed with anything.
What not to do
These are the combinations an authority has warned about. It is not a list of everything dangerous: a substance nobody has warned about has not been cleared, and none of this is permission to mix.
Never mix
Chloramine gases are released. These are severe respiratory irritants: exposure causes coughing, shortness of breath, chest pain, wheezing, nausea, watery eyes and irritation of the throat, nose and eyes, and in serious cases pneumonia and fluid in the lungs. In an enclosed space such as a bathroom, concentrations build quickly. Get into fresh air at once and seek medical advice. FEELING BETTER SHORTLY AFTERWARDS IS NOT AN ALL-CLEAR: the regulator recommends medical observation for 24 to 48 hours after overexposure, because fluid on the lungs can be delayed.
Never mix
Chlorine gas is released. It is an immediately dangerous respiratory irritant with a sharp distinctive smell. Even low levels for short periods irritate the eyes, nose and throat and cause coughing and breathing problems; higher levels cause chest pain, severe breathing difficulty, vomiting and lung damage, and very high levels can be fatal. Leave the area for fresh air at once and seek medical advice. FEELING BETTER SHORTLY AFTERWARDS IS NOT AN ALL-CLEAR: the regulator recommends medical observation for 24 to 48 hours, because fluid on the lungs can be delayed.
Never mix
Chloroform and related chlorinated compounds are formed. The reported effects of exposure are dizziness, nausea, headaches and loss of consciousness. Losing consciousness in the presence of the reaction that caused it is what makes this more dangerous than the symptom list suggests, because the exposure continues while the person is unable to leave. Anyone affected should be moved into fresh air immediately and medical advice sought.
Never mix
Chlorine and other toxic gases are released. Chlorine is an immediately dangerous respiratory irritant: low levels irritate the eyes, nose and throat and cause coughing and breathing problems, and high levels cause severe breathing difficulty and lung damage. Leave the area for fresh air at once and seek medical advice. Feeling better shortly afterwards is not an all-clear — the regulator recommends medical observation for 24 to 48 hours, because fluid on the lungs can be delayed.
Never mix
The regulator's own wording is that the two react EXPLOSIVELY in the presence of water — which is to say, in the only circumstances either product is ever used in. Both are chlorine sources, so chlorine gas is released as well, and chlorine is a severe respiratory irritant whose effects can be delayed. If this has happened, get into fresh air at once, do not go back into the room to ventilate it, and seek medical advice. Feeling better shortly afterwards is not an all-clear.
Never mix
The regulator's instruction is that phosphoric acid must be stored to avoid contact with water, ammonia, BLEACH and nitromethane because violent reactions occur. Acid and hypochlorite together release chlorine gas, which is a severe respiratory irritant. In a bathroom the space is small and the concentration builds quickly. Leave the room, do not return to open a window, and seek medical advice.
Never mix
Chlorine gas is released, and this is the strongest domestic version of the acid-and-bleach reaction because hydrochloric acid is the strongest acid a householder is likely to have. Chlorine causes coughing, chest tightness and shortness of breath, and its effects can be delayed by hours. Get well clear, do not go back in to ventilate, and seek medical advice even if breathing settles.
Sodium hypochlorite (chlorine bleach) is unsafe on Wool
Unsafe
Do not do this. The risk is established, and it is described below.
The wool industry body advises against bleach of BOTH kinds, which is wider than the chlorine-only warning most laundry advice gives.
Precautions
- Check the manufacturer's instructions
Evidence
Strongly supported
Sources
Best detergent to use when washing wool
The Woolmark Company · Trade or professional body
Relied on for: That bleach must never be used when washing wool, chlorine-based or oxygen-based. (states this directly)
Kirk-Othmer Encyclopedia of Chemical Technology
John Wiley & Sons · Reference work
Relied on for: That hypochlorite is an aggressive oxidant which attacks protein fibres, and that keratin is a protein. (background and mechanism only)
Sodium hypochlorite (chlorine bleach) may damage Cotton
Best avoided
The available guidance advises against this.
Cumulative and invisible: the fabric looks fine and fails later, because the damage is to the cellulose chains rather than the appearance.
Precautions
- Limit the contact time
- Check the manufacturer's instructions
Evidence
Strongly supported
Sources
Scientific Reports (Nature Portfolio), 2023 · Scientific literature
Relied on for: That ten chlorine-based wash cycles reduced cotton cellulose limiting viscosity number by more than eighty per cent against about half after one hundred ordinary commercial cycles, with tensile strength falling correspondingly. (states this directly)
Sodium hypochlorite (chlorine bleach) may damage Stainless steel
Best avoided
The available guidance advises against this.
Chloride, not oxidation, is the problem: chloride ions break down the passive layer locally and produce pitting.
Precautions
- Limit the contact time
- Rinse thoroughly afterwards
- Never mix with other cleaning products
Evidence
Supported
Sources
Cleaning methods for stainless steel
British Stainless Steel Association · Trade or professional body
Relied on for: That chloride-containing solutions including hypochlorite bleaches can cause unacceptable surface staining and pitting and should not be used, that contact time must be minimal where they are used, and that soaking sinks or cookware in dilute bleach overnight is not advisable. (states this directly)
Care and Maintenance of Stainless Steel
British Stainless Steel Association, Stainless Steel Advisory Service, 2001 · Trade or professional body
Relied on for: That chloride solutions are not to be used on stainless steel in the treatment of stains and water marking. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Finished wood flooring
Unsafe
Do not do this. The risk is established, and it is described below.
Precautions
- Test on an inconspicuous area first
- Check the manufacturer's instructions
Evidence
Supported
Sources
Maintenance, and How to Clean and Take Care of Your Wood Floors
National Wood Flooring Association (NWFA) · Trade or professional body
Relied on for: That bleach and ammonia-based cleaners should be avoided because they can strip the finish off wood floors and cause permanent damage. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Acrylic
Unsafe
Do not do this. The risk is established, and it is described below.
Full strength. The same manufacturer separately directs adding bleach to a full bath of water to flush airjet pipework, which is a dilute circulating flush rather than a cleaner on the surface.
Precautions
- Dilute before use
- Ventilate the area
- Never mix with other cleaning products
- Check the manufacturer's instructions
Evidence
Strongly supported
Sources
KALLISTA (Kohler Co.) · Manufacturer documentation
Relied on for: That full-strength bleach or ammonia cleaning solutions must not be used on airjet baths because chemically active cleaning solutions can damage the bath surface. (states this directly)
Sodium hypochlorite (chlorine bleach) must never be mixed with Hydrogen peroxide
Unsafe
Do not do this. The risk is established, and it is described below.
Two oxidisers, which is why the combination is attempted. The regulator lists them as incompatible with each other.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Wear eye protection
Evidence
Strongly supported
Sources
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That sodium hypochlorite is not compatible with hydrogen peroxide. (states this directly)
Right to Know Hazardous Substance Fact Sheet: Hydrogen Peroxide
New Jersey Department of Health · Government or regulator
Relied on for: That hydrogen peroxide is corrosive, reactive and an oxidiser carrying its own incompatibility list. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Waterproof outerwear
Unsafe
Do not do this. The risk is established, and it is described below.
Precautions
- Check the manufacturer's instructions
- Never mix with other cleaning products
Evidence
Strongly supported
Sources
W. L. Gore & Associates (GORE-TEX brand) · Manufacturer documentation
Relied on for: That bleach must not be used on the garment. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Laptop keyboard
Unsafe
Do not do this. The risk is established, and it is described below.
Named on the manufacturer's prohibited list. Bleach on a keyboard is not a stronger version of the approved method; it is on the list of things that damage the product.
Evidence
Supported
Sources
Guidance for Keeping Your Dell Technologies Equipment Clean
Dell Technologies · Manufacturer documentation
Relied on for: That bleach and chlorine-based cleaners are among the named substances that must not be used on the equipment. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Fridge door seal
Unsafe
Do not do this. The risk is established, and it is described below.
Bleach is named on the prohibited list and gaskets are named among the surfaces it covers - which is unfortunate, because a discoloured seal is exactly what people reach for bleach on.
Evidence
Supported
Sources
Cleaning the Interior of the Refrigerator
Whirlpool Corporation · Manufacturer documentation
Relied on for: That bleaches are among the abrasive or harsh cleaners which must not be used on plastic parts, interior and door liners, or gaskets. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Mobile phone
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Supported
Sources
How do I clean my Galaxy phone?
Samsung Electronics · Manufacturer documentation
Relied on for: That bleaches must not be applied or sprayed on the phone. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Finished wood flooring
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Strongly supported
Sources
Maintenance, and How to Clean and Take Care of Your Wood Floors
National Wood Flooring Association (NWFA) · Trade or professional body
Relied on for: That bleach and ammonia-based cleaners strip the finish off wood floors and cause permanent damage. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Oiled wood
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Strongly supported
Sources
Maintenance, and How to Clean and Take Care of Your Wood Floors
National Wood Flooring Association (NWFA) · Trade or professional body
Relied on for: That bleach strips the finish off wood floors and causes permanent damage, and that the cleaner must be one made specifically for the finish. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Carpet
Unsafe
Do not do this. The risk is established, and it is described below.
Colour loss on most textiles is complete or moderate and is correctable only by dyeing or patching. Olefin is the stated exception, and most people do not know which fibre they have.
Evidence
Strongly supported
Sources
Consumer Floor and Furnishings Care Information: carpet topics
Institute of Inspection, Cleaning and Restoration Certification (IICRC) · Trade or professional body
Relied on for: That complete or moderate colour loss occurs on most textiles exposed to chlorine bleach, that the usual result is light yellow to white discolouration, that only dyeing or patching can correct it, and that olefin is the exception. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Car interior
Unsafe
Do not do this. The risk is established, and it is described below.
The maker's words are chemical attack, and they are about wipes rather than about neat bleach — a product most people would consider mild enough for a car seat.
Evidence
Strongly supported
Sources
General Motors LLC, published via NHTSA · Manufacturer documentation
Relied on for: That wipes which are scented or contain bleach can cause chemical attack on interior surfaces and should not be used, and that colour transfer to the wipe or a change in appearance when tested in an inconspicuous location are indicators of chemical attack. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Door liner
Unsafe
Do not do this. The risk is established, and it is described below.
Evidence
Supported
Sources
Cleaning the Interior of the Refrigerator
Whirlpool Corporation · Manufacturer documentation
Relied on for: That warm water with mild dish soap and a microfibre cloth is used, that gaskets are cleaned with a damp cloth and mild soap lifting the folds, that all parts must be completely dry before reinstalling, and that abrasives, window sprays, scouring cleansers, waxes, concentrated detergents, bleaches and petroleum-based cleansers must not be used on plastic parts, liners or gaskets. (states this directly)
Sodium hypochlorite (chlorine bleach) is unsafe on Fridge door seal
Unsafe
Do not do this. The risk is established, and it is described below.
Bleach is prohibited on a fridge gasket by the same manufacturer whose washer guidance uses dilute bleach on a washer seal.
Evidence
Supported
Sources
Cleaning the Interior of the Refrigerator
Whirlpool Corporation · Manufacturer documentation
Relied on for: That warm water with mild dish soap and a microfibre cloth is used, that gaskets are cleaned with a damp cloth and mild soap lifting the folds, that all parts must be completely dry before reinstalling, and that abrasives, window sprays, scouring cleansers, waxes, concentrated detergents, bleaches and petroleum-based cleansers must not be used on plastic parts, liners or gaskets. (states this directly)
Quaternary ammonium compounds must never be mixed with Sodium hypochlorite (chlorine bleach)
Unsafe
Do not do this. The risk is established, and it is described below.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Keep away from children and pets
Evidence
Supported
Sources
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That sodium hypochlorite may react violently or explosively with ammonia compounds, quaternary ammonium salts named among them, to release chlorine and other toxic gases. (states this directly)
Right to Know Hazardous Substance Fact Sheet: Chlorine
New Jersey Department of Health · Government or regulator
Relied on for: The character of chlorine exposure and the delayed onset of pulmonary edema, which is what makes the released gas dangerous. (states this directly)
Ammonia must never be mixed with Sodium hypochlorite (chlorine bleach)
Unsafe
Do not do this. The risk is established, and it is described below.
Regulator sheets state this hazard at substance level, not only at product level.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Keep away from children and pets
Evidence
Strongly supported
Sources
Right to Know Hazardous Substance Fact Sheet: Ammonia
New Jersey Department of Health · Government or regulator
Relied on for: That ammonia reacts violently with halogens including chlorine, and with calcium hypochlorite. (states this directly)
Right to Know Hazardous Substance Fact Sheet: Chlorine
New Jersey Department of Health · Government or regulator
Relied on for: That chlorine is a strong oxidiser, reacts with water to form acid solutions, and can cause pulmonary edema, described as a medical emergency. (states this directly)
Sodium dichloroisocyanurate must never be mixed with Sodium hypochlorite (chlorine bleach)
Unsafe
Do not do this. The risk is established, and it is described below.
A chlorine-releasing tablet and a bleach bottle, which a state health department describes as reacting explosively in the presence of water — which is the only state either is ever used in.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Keep away from children and pets
- Consider professional help
Evidence
Strongly supported
Sources
Right to Know Hazardous Substance Fact Sheet: Sodium Dichloro-Isocyanate (RTK 1694)
New Jersey Department of Health, 2002 · Government or regulator
Relied on for: That sodium dichloroisocyanurate reacts explosively with calcium hypochlorite or sodium hypochlorite in the presence of water. (states this directly)
Phosphoric acid must never be mixed with Sodium hypochlorite (chlorine bleach)
Unsafe
Do not do this. The risk is established, and it is described below.
A regulator naming BLEACH by that word on the fact sheet for a substance sold to consumers as a descaler and rust treatment.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Wear gloves
- Wear eye protection
- Consider professional help
Evidence
Strongly supported
Sources
Right to Know Hazardous Substance Fact Sheet: Phosphoric Acid (RTK 1516)
New Jersey Department of Health, 2004 · Government or regulator
Relied on for: That phosphoric acid must be stored to avoid contact with water, ammonia, bleach and nitromethane since violent reactions occur. (states this directly)
Hydrochloric acid must never be mixed with Sodium hypochlorite (chlorine bleach)
Unsafe
Do not do this. The risk is established, and it is described below.
The strongest domestic version of the acid-and-bleach reaction, and an outdoor one, where people assume ventilation is not a concern.
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Wear gloves
- Wear eye protection
- Consider professional help
Evidence
Strongly supported
Sources
Right to Know Hazardous Substance Fact Sheet: Hydrogen Chloride (RTK 1012)
New Jersey Department of Health, 2016 · Government or regulator
Relied on for: That hydrogen chloride reacts with oxidising agents including chlorine to form toxic chlorine gas. (states this directly)
Dangers of Mixing Bleach with Cleaners
Washington State Department of Health · Government or regulator
Relied on for: That bleach must not be mixed with acidic products because toxic chlorine gas is produced. (states this directly)
Precautions
- Never mix with other cleaning products
- Ventilate the area
- Wear gloves
- Wear eye protection
- Keep away from children and pets
- Rinse thoroughly afterwards
In detail
Sodium hypochlorite is the active ingredient in household chlorine bleach. It works by oxidation: it destroys the coloured part of stain molecules and it damages the cellular structures of micro-organisms, which is why the same product both removes colour and disinfects. Those are genuinely powerful capabilities, and there are jobs no milder product does as well. The oxidation is not selective. Bleach acts on fabric dyes as readily as on stains, degrades protein fibres including wool and silk, and its chloride content presents a pitting-corrosion risk to stainless steel if it is left in contact rather than rinsed away. Separately from what it does to materials, sodium hypochlorite reacts dangerously with several other common household products, releasing toxic gases when it does. The rule that follows is short and admits no exceptions: use it on its own, rinse thoroughly, and never combine it with another cleaning product.
Properties
- Chemical name
- Sodium hypochlorite
- pH
- Strongly alkaline
What works
Sodium hypochlorite (chlorine bleach) is effective against Mould Disputed
THE SOURCES DISAGREE, AND THE DISAGREEMENT IS THE ANSWER. All of them put moisture control first and physical removal with detergent second; where they part company is whether a bleach step afterwards is worth adding, and at what dilution.
Sodium hypochlorite (chlorine bleach) is safe on, in specific conditions, Solution-dyed acrylic
Safe only in specific conditions
This is only appropriate within specific limits. Outside those limits, no claim is made.
An unusual positive clearance for bleach on a textile, and it exists because of how the fibre was dyed rather than because outdoor fabric is tough.
Only within these limits:
- one cup of bleach with a quarter cup of mild soap per gallon of water
- left to soak for 15 minutes, then worked with a sponge, clean towel or very soft bristle brush
- rinsed thoroughly to remove all residue, then air dried — never machine dried
- surrounding non-Sunbrella fabric protected, because bleach may discolour it
- solution-dyed acrylic only; not surface-dyed or printed outdoor fabric
The manufacturer states that for severe growth the bleach quantity may be increased.
Precautions
- Wear gloves
- Wear eye protection
- Never mix with other cleaning products
- Rinse thoroughly afterwards
- Dispose of responsibly
Evidence
Supported
Sources
Sunbrella Upholstery Care and Cleaning
Glen Raven, Inc. (Sunbrella), 2023 · Manufacturer documentation
Relied on for: That mould and mildew are removed with one cup of bleach and a quarter cup of mild soap per gallon of water, sprayed on, soaked for 15 minutes, cleaned with a sponge or very soft brush, rinsed thoroughly and air dried, and that the fabric is solution-dyed acrylic. (states this directly)
Sodium hypochlorite (chlorine bleach) is safe on, in specific conditions, Olefin
Safe only in specific conditions
This is only appropriate within specific limits. Outside those limits, no claim is made.
Only within these limits:
- The fibre must actually be olefin — most readers cannot tell, and being wrong is irreversible
- Bleach-proof means the COLOUR survives; it is not a clearance for the backing, the adhesive or anything underneath
The single exception in a category where everything else is permanent damage, and a manufacturer recommends the fibre for laundry rooms and poolside areas on exactly this basis.
Evidence
Supported
Sources
Consumer Floor and Furnishings Care Information: carpet topics
Institute of Inspection, Cleaning and Restoration Certification (IICRC) · Trade or professional body
Relied on for: That olefin fibres are bleach-proof, are the one exception to chlorine bleach causing colour loss on textiles, and should be considered for carpeted laundry rooms and areas near swimming pools. (states this directly)
Where the answer depends
Sodium hypochlorite (chlorine bleach) may damage Coated upholstery
Not established
Whether this is safe is not established by any authoritative source. That is not the same as it being safe — it means the evidence needed to answer has not been published. Do not treat this as permission to proceed.
Evidence
Plausible mechanism, untested in this application
Sources
ACT Coated Fabric Selection Guide for Healthcare Upholstered Seating
Association for Contract Textiles · Trade or professional body
Relied on for: That coated fabrics are soft-surface materials, and that cleaners, sanitizers and disinfectants formulated for use on hard surfaces are not intended for use on soft surfaces and could damage vinyl, polyurethane and silicone upholstery fabrics. (applied to this case rather than stated directly)
Why
- Sodium hypochlorite (chlorine bleach) is explained by Oxidation and bleaching
- Sodium hypochlorite (chlorine bleach) is explained by Corrosion and passivation
Its chloride content is what threatens stainless steel — a separate property from its oxidising power.
- Sodium hypochlorite (chlorine bleach) is explained by Cleaning, disinfecting and sterilising
- Sodium hypochlorite (chlorine bleach) is explained by Cleaning products and animals in the home
- Sodium hypochlorite (chlorine bleach) is explained by Colour coding, and why professionals never carry one cloth
Hacks and claims involving this
- Leaving bleach in the sink overnight Does not work
- Following bleach with an alcohol sanitiser Does not work
- You will smell it if the fumes are dangerous Does not work
- Decanting bleach into another container Does not work
- Combining bleach and hydrogen peroxide Does not work
Where the sources disagree
What is the correct bleach dilution and dwell time for sanitising a chopping board at home?
The two positions have the same scope, which is what makes the disagreement a real one. All three are university extension services addressing the same domestic task on the same two materials, and Arizona's reference list traces to the same federal fact sheets the others rest on. They are not answering different questions — they publish different numbers, spanning roughly a factor of two in concentration and one minute to several in dwell, with rinsing explicit in two and absent in the third. THERE IS A LIKELY REASON, AND IT RESOLVES NOTHING. Maine states its dilutions in PARTS PER MILLION as well as in spoons — 50 to 200 ppm routine, around 100 ppm for a deep soak. If the target is a concentration range rather than a recipe, three volumetric instructions landing in one band is what independent translation of one target looks like. That is an explanation, not a reconciliation: the other two publish no ppm figure, so there is no way to know they aimed at the same band.
What to do: Do not treat any single household bleach dilution as the correct one. All three fall in the same broad band, so the practical answer is to follow the dilution printed on the bottle in hand, apply it to an already-washed board, leave it for the time that product states, and rinse a food-contact surface afterwards. The steps all three agree on matter more than the number they disagree about: wash first with hot soapy water and a brush, sanitise as a separate step, and replace a board whose grooves mean it can no longer be cleaned.
The sources genuinely disagree
Should chlorine bleach be used on household mould, and at what dilution?
Read side by side these bodies agree on far more than the disagreement suggests, and the agreement is the useful part. All three put MOISTURE CONTROL first and say the growth returns without it. All three make PHYSICAL REMOVAL with detergent and water the actual method. None presents bleach as the way mould is cleaned. What they differ on is whether an optional kill step afterwards earns its place — and the answer tracks the WATER, not the mould. Where the water was clean, the bleach step is merely offered and the federal guide declines to recommend it; where it was floodwater or sewage, both bodies that give dilutions positively recommend it, because the concern has shifted from mould to what else the water carried. The federal guide's reason for declining is not that bleach fails: it is that killing without removing leaves an allergenic residue, and that a background level of spores is normal once the area is dry.
What to do: Fix the water first — every source says the mould returns otherwise. Then remove the growth physically, scrubbing hard surfaces with detergent and water and drying completely; that is the method all three bodies give. Porous material that has grown mould — carpet, plasterboard, insulation, ceiling tiles — is discarded rather than treated, on every source. If you add a bleach step on a hard surface afterwards, that is a position two public bodies support and one declines to recommend; use the conditions they all agree on: dilute, ventilate, gloves and unvented eye protection, and never mix bleach with ammonia, with acids such as vinegar, or with any other product. Mould over about ten square feet, or after flooding or sewage, is not a cleaning job.
The sources are answering different questions
Sources for this page
Sources
NIOSH Pocket Guide to Chemical Hazards
US National Institute for Occupational Safety and Health (NIOSH), CDC · Poison or chemical-safety authority
Relied on for: That chlorine and chloramine are hazardous respiratory irritants recognised by an occupational health authority.
Right to Know Hazardous Substance Fact Sheet: Sodium Hypochlorite
New Jersey Department of Health · Government or regulator
Relied on for: That a 5.25% solution of sodium hypochlorite in water has a pH of 10.8 to 11.4, that the substance is classified corrosive and a strong oxidizer, and that it decomposes and must be stored away from light. (states this directly)