solvents and thinners

Because solvents (for cleaning up or softening) and thinners (for diluting or extending) are useful not only in painting but in other areas such as modelling or mouldmaking/casting I have given them their own sub-section here. Many common solvents (such as water, acetone or white spirit) can be used equally as thinners, though not all. Some may be needed only occasionally and then only for special purposes so it’s often difficult to remember what each can do. One may only want a quick reminder, so I’ve done my best to keep to the most significant facts. I’ve included suppliers and example prices from early 2015. Although I’ve used many over the course of the years I’m by no means an expert on solvents and thinners .. so please don’t post here asking me questions such as how to remove Siberian coconut oil from a treasured rug! If there’s no clue already here, I won’t have any others.

The safety data provided here is no more than a summary and therefore should not be fully relied upon! It is very important especially in the case of solvents or thinners to read the latest MSDS (Materials Safety Data Sheet) for the product which nowadays can be obtained online from the manufacturer’s or the retailer’s websites. Also, and if in doubt, you can find health&safety information for most chemicals in common use on the ‘Public Health England’ site below, through an alphabetical list

http://www.hpa.org.uk/HPAwebHome/

Actually it’s perhaps best to consult sites like this one for a fairly clear idea of the health risks first. Unfortunately some official MSDS documents aren’t very clear at all, as if they’re not written for the ordinary public but rather for industrial chemists ..  or their lawyers! I’ve been referring to them for years and even I’m not certain about the extent of the dangers from some materials i.e. what would actually constitute harmful exposure! For this reason and to cover any doubts I would recommend that whatever solvent or thinner you’re using you make sure of at least the following:

– that the room is well ventilated ( i.e. more than one window open! ) and that no ‘innocent bystander’ is sharing it, or will be for a while afterwards

– that there are no naked flames around, no cigarettes, not even a soldering iron on the go .. no possible way that flammable vapour could be ignited!

– don’t leave containers open for longer than necessary. It helps if you decant smaller amounts of solvent into handier glass or resistant plastic (i.e. polypropylene) jars. I use sandwich paste jars which have tight-sealing lids but flip-tops would be even better as long as the plastic isn’t affected.

– wearing nitrile gloves is highly recommended (more resistant to chemicals than latex), but otherwise avoid all contact with the skin i.e. if using tissue swabs wetted with solvent at least hold them between a piece of polythene (I wear just a couple of fingers cut from rubber gloves if I don’t want to put the whole glove on)

– use eye-protection if there’s even the smallest likelihood of splashes and even if you’re the type that doesn’t splash, don’t forget about the effect of vapour build-up on your eyes!

– store solvents in a safe, cool place well away from sources of heat and direct sunlight. In the industrial workplace solvents usually have to be stored in a locked metal cabinet so safety measures in the home or private studio should really be the same

It doesn’t take long to realize that there are groups of products that have basically the same main ingredient, but this doesn’t mean that they can all be freely used for the same purposes. There are often slight differences in composition which can produce very different properties! An example is the group that contains naphtha (derived from petroleum) as it’s base, usually more than 80% and some hardly anything else. The differences derive either from the way the naphtha is processed or from the addition of certain other things. This group includes the different forms of ‘white spirit’ as it’s known in the UK, ‘mineral spirits’ or ‘Stoddard solvent’ in the US, lighter fluid, WD-40 and many ‘adhesive cleaners’. All of them will perform in much the same way as solvents for removing oily, greasy or waxy substances or dissolving some types of glue .. but one would never, for example, thin oil paint with WD-40 or fill a lighter with white spirit!

On that subject, a question that’s often asked is .. If a paint brand manufacturer (such as Humbrol for enamel paints or Winsor & Newton for artist’s oil paints) recommends the use of their own thinners when working with the paint, does this mean it will produce the best results or can one get them equally using other products? There is no straight answer to this unfortunately! There will be many different opinions if one looks online and the only sure way is to experiment oneself. The one thing you can be certain of is that the manufacturer’s own brand of thinners will be more expensive and it is very likely to be just a combination of materials that could be obtained easily elsewhere .. if one knew the combination!

Supplier and price information shown was last updated May 2017.

White spirit

What we in the UK call ‘white spirit’ and known in the US as ‘mineral spirits’ (also referred to by some as ‘turpentine substitute’) is primarily marketed as a general-purpose thinner and brush cleaner when working with oil or spirit-based paints. It is a thin (thinner than water), colourless liquid and has a strong, sharp oil paint-like smell. Not miscible with water. It is claimed that, if used as a thinner, white spirit will not affect the drying time of oil-based paint. In fact it can speed up the drying of some e.g. Humbrol enamels

It is basically naphtha which is derived from petroleum (i.e. a ‘petroleum distillate’), but there are a few different types of white spirit which differ according to how the naphtha has been processed i.e. whether it has been ‘desulfurized’ or not (the photo above includes ‘genuine’ turpentine, which is not a form of white spirit but a different substance and dealt with later). If you look on the MSDS sheet for any brand of white spirit you will see the principal ingredient listed as either ‘naphtha (petroleum) hydrodesulfurized heavy’ or ‘naphtha (petroleum) hydroteated heavy’. Bartoline now produces a ‘Premium Low odour White Spirit’ which the MSDS lists as ‘naphtha (petroleum) hydrotreated heavy’, so basically the same thing but apparently odourless because further refinement has removed some of the ‘aromatic compounds’. Just remember that these odourless forms are not ‘safer’ or any less potentially irritant just because one can’t smell them as much, but it does make working with them more pleasant!

Uses as cleaner or thinner for most oil-based paints, including artists’ oil paints; used industrially as a degreaser especially for removing oils, greases from metal; will clean up uncured silicone rubber, can even be added to the mix to increase volume temporarily and can be added to Platsil Gel silicones to make a silicone paint; will dissolve coloured pencil and pastels to create washes or tints; when used as a carrier for pigment when staining wood, will penetrate better; good thinner for Humbrol enamels

Safety data Flammable liquid and vapour; harmful if swallowed; vapours may cause drowsiness and dizziness; repeated skin contact may cause dryness and cracking. Inspite of what the strong smell may suggest, white spirit is classed mainly as an ‘irritant’ and is considered harmful only in situations of extreme exposure i.e. if swallowed, inhaled progressively or soaking the skin for a long period

Obtainable all decorator’s, ironmongers or DIY stores. Price e.g. B&Q £2.31 per 750ml, £3.74 per 2litres. Bartoline Premium Low Odour White Spirit £3.92 per 750ml (Note 2017 having used the ‘Low Odour’ type for a couple of years now I’ve found it just as effective as a cleaner, though I still use regular white spirit as a thinner.)

WD-40

Although the exact composition of WD-40 is shrouded it’s fairly clear from reading the MSDS sheets what it contains and why it has the ‘2,000+ uses’ claimed for it. It is mainly naphtha (80%) with a mineral oil dissolved in it (15%) and the other 5% is carbon dioxide gas as a propellant. The naphtha will do the cleaning, but when WD-40 is applied to a surface this will quickly evaporate leaving the oil as a thin film to lubricate or protect.

Uses as a lubricant; as protection for metal against corrosion and also rust remover (or loosener of rusted parts); displaces moisture (WD stands for ‘water displacement’). Also often used as degreaser and cleaner tackling grease, some adhesives, even chewing-gum. Can damage some plastics.

Safety data Highly flammable. Classed as harmful if swallowed or with repeated exposure (causing dizziness, skin dryness)

Obtainable household, car, ironmongers, DIY stores or supermarkets. Price e.g. Tesco £3.00 per 200ml spray can; Halfords £3.99

Lighter fluid (petroleum distillate)

This is sold in cans as fuel for filling petrol lighters e.g. Zippo lighters, but also described as ‘cleaning fluid for the home, garage and studio’. It is usually described on the can as ‘solvent naphtha (petroleum) light aliph’

Uses removes oil or grease-based stains including tar, solvent-based inks and some soft glues (i.e. good for removing residues left from tape or labels)

Safety data highly flammable; harmful if swallowed or inhaled in concentration; can cause skin irritation;

Obtainable most newsagents or supermarkets in 133ml cans e.g. Ronsonol c. £1.70

Turpentine

Whereas ‘white spirit’ is mineral or petroleum-based, turpentine on the other hand is vegetable-based, non-hydrocarbon, most often distilled from the resin of pine trees. It’s often referred to as an oil (e.g. Oxford English ‘a volatile pungent oil distilled from gum turpentine or pine wood, used in mixing paints and varnishes and in liniment’). Can be expensive and there is no cheap (i.e. B&Q or £shop) version. Strong smelling, considered harmful (more so than white spirit) and evaporates much more slowly. Because turpentine is plant-based many assume it must be healthier than other solvents but this is not the case!

Uses for thinning oil-based paints, for many superior to white spirit when working with artists’ oils; as ingredient in varnishes or wax polishes (i.e. beeswax dissolved in turpentine as furniture wax); also dissolves resins such as Dammar resin; medicinal use (see below)

Safety data flammable; harmful to lungs and respiratory system; irritating to skin; vapour irritating to eyes. With turpentine the confusion is understandable because it has been used in the past as a relief for joint or muscle pain, even toothache, by being rubbed on the skin. Also as inhalant to relieve congestion!

Does thinning with turpentine give a smoother oil-based paint than thinning with white spirit? Some artists do say that tube oil paint thins more evenly using turpentine and that colours are brighter, but also that turpentine discolours in time.

Obtainable art materials suppliers e.g. Winsor & Newton Distilled Turpentine c. £4.00 per 75ml; c. £9.00 per 250ml

Bartoline ‘Clean Spirit’

This is marketed as a ‘water-based alternative’ to white spirit or turpentine, with a minimal solvent content (below 8%). Bartoline claims that it will clean both oil and water-based paints from brushes and can be used as a degreaser. It is apparently odourless, non-flammable and classed as non-toxic. I haven’t used this yet myself (it and other odourless versions of white spirit are comparatively new) but will update here as soon as I do. One thing I can say though is that if it is water-based it obviously can’t be used as a thinner .. it’s just for cleaning.

Obtainable B&Q Bartoline ‘Clean Spirit’ £1.68 per 1litre ( Update 2017 at B&Q this has been replaced by Diall Clear Water Based Clean Spirit £2.00 per 750ml )

Acetone

Widely used as a solvent and cleaner; present in many paints (particularly spraypaints) and some glues. Colourless, thin liquid, evaporates quickly with cooling effect, sweet mint-like smell. Miscible with water or alcohol. Nail polish remover used to be mainly acetone, but now this is either acetone free or has a certain amount combined with less aggressive ingredients.

Uses will dissolve many paints such as cellulose-based (car paints), varnishes, lacquers, fats, oils, waxes and some glues; used for thinning polyester and epoxy resins, will clean up uncured polyester, polyurethane and epoxy; pure acetone will dissolve superglue but only before it hardens completely; will attack and dissolve forms of styrene plastic inc. styrofoam, polystyrene; good degreaser of surfaces such as metal prior to painting; can be used as a releasing agent for transfering a toner photocopy (not inkjet print) to another surface.

To witness what acetone does to expanded polystyrene (which is known as ‘styrofoam’ in the US) look at this video

http://www.youtube.com/watch?v=h9Jx8NRkWTo

Safety data highly flammable; irritating to eyes; dries the skin quickly, prolongued contact will cause dryness and cracking, can cause damage to eyes and nasal passages; vapours may cause drowsiness and dizziness

Obtainable cfsnet.co.uk £6.09 per 1 litre, £19.76 per 5 litre; easycomposites.co.uk £3.60 per 500ml, £5.94 per 1 litre; Tiranti £7.80 per 250ml, £17.94 per 1 litre

Cheapest for larger quantities is specialplasters.co.uk £6.36 per 1 litre, £10.20 per 5 litre, £35.40 per 25 litre (2017)

Toluene

A solvent ingredient in many paints (particularly spraypaints) and glues. Thin, colourless liquid with a strong, sweet smell. Not miscible with water. A specialist material, expensive and not usually available from ‘general’ suppliers.

Uses as a solvent and thinner for many paints and glues; effective as solvent/thinner for prosthetic (addition cure) silicones and paints (i.e. SmoothOn ‘Psycho Paint); is used to melt/weld styrene parts in model kit making (but not to be confused with dichloromethane which does the same)

Safety data highly flammable; vapour (heavier than air) explosive when exposed to heat or sources of ignition; irritating to eyes, throat, lungs and skin; toxic to inhale or ingest

Obtainable 4D modelshop £17.99 per 1litre ( Note 2017 no longer found on shop website)

Methylated spirits

In the US this is known as ‘denatured alcohol’ which better conveys the fact that it is ethanol which has been rendered undrinkable by adding methanol (c. 10%), hence the UK name. The usual mauve/purple colour is just a dye added to identify it.

Uses will disolve or thin shellac or shellac-based varnishes (hard shellac is dissolved in it to create the varnish); can be used to thin epoxy resin; used as a fuel for small burners; will help in removal of ink stains and permanent markers from non-porous surfaces such as metal, glass, plastic .. generally a good cleaner for hard surfaces; as a preservative for biological specimens; to clean/disinfect skin before surgery; window washing (streak-free polishing with a 50-50 mix with distilled water);

Safety data highly flammable; dangerous by ingestion; harmful by inhalation and skin contact (will de-fat skin and strip it of moisture)

Obtainable B&Q (Diall brand) £3.87 per 500ml

Dichloromethane (methylene chloride)

A commonly used plastic solvent used to melt/bond certain plastics together (styrene, butyrate, ABS, acrylic, perspex). Architectural model-makers use this a great deal when building in white styrene because there are virtually no traces of gluing left outside the join. DCM is also recognised as a very effective general solvent and is a common component in paint-stripper. It is also one of the most dangerous! Architectural model-makers commonly use a special solvent dispenser rather than taking from an open bottle, which is meant to reduce build-up in the air.

Safety data harmful to skin (can cause burning sensation, prolonged contact can dissolve fatty tissues), harmful by inhalation (particular hazard because when inhaled the body metabolizes it, producing carbon monoxide .. but apart from that can cause drowsiness, headache etc. Because DCM evaporates very quickly concentrations of vapour can easily occur especially in confined spaces. Classified as a Category 3 carcinogen in the European Community i.e. it has been linked to cancer.

Obtainable as Plastic Weld solvent from 4D modelshop £3.70 per 57ml, or ema-models.co.uk  £6.00 per 500ml can

Isopropyl alcohol

Also known as ‘isopropanol’. Colourless liquid, evaporates quickly. Miscible in water and alcohol. One of the least toxic of solvents or cleaners, but good ventilation is as always still necessary. Sometimes referred to as ‘rubbing alcohol’ but see ‘Surgical spirit’ below.

Uses as a cleaning agent in precision engineering, optics and electronics; solvent for natural resins and gums including shellac; dissolves oils; removes some sticky label glues; preserves biological specimens

Safety data highly flammable; toxic if swallowed or inhaled; irritating to skin; vapours can cause drowsiness or dizziness

Obtainable from stage makeup suppliers (sold as solvent for glues used to attach false hair or prosthetics), electronics stores. Also sold as whiteboard cleaner. CharlesHFox £18.00 per 1litre; Maplin (electronics) Servisol IPA 170 in 400ml spraycans £9.99, or 1litre as liquid £14.99.

A good source for larger quantities is specialplasters.co.uk i.e. currently (2017) £4.38 per 1litre, £15.00 for 5litres

Surgical spirit

Also known as ‘rubbing alcohol’ with ethanol (or ‘ethyl alcohol’) as its main constituent along with methanol (or ‘methyl alcohol’). Can also contain isopropyl alcohol ( versions containing mainly isopropyl alcohol usually called ‘Isopropyl rubbing alcohol’ ). Like methylated spirits it is often coloured and made ‘bitter’ to prevent drinking. It’s most used as a disinfectant and as a toughener for the skin. Some brands contain castor oil to counteract dryness.

Uses traditionally used by guitarists and ‘hill walkers’ alike to prevent blisters by toughening the skin; as a cleaner/disinfectant for minor cuts, clinical equipment and surfaces and skin prior to injections

Safety data highly flammable; harmful if swallowed; good ventilation necessary to avoid inhalation dangers; irritating to skin, can cause burning sensation

Obtainable chemists e.g. £1.79 per 200ml Superdrug