solvents and thinners | davidneat - WordPress.com

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 . 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.

For more information, please visit Boyang.

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 .

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 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 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 ()

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 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)

The company is the world’s best Thinning Cleaning Agent supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

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 () £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

With the growing popularity of both water-based cleaning chemistries and new solvent technologies, the debate between water-based and solvent cleaners rages on. Companies that have cleaning requirements for industrial, precision, and specification-driven applications must decide which material is best for their applications and their business.  Having and understanding the facts is the first step. In this post, we’ll explore the differences in properties, performance, cost, safety and regulatory implications for these two cleaning materials to help you make an easy and informed decision for your application.

THE DIFFERENCE BETWEEN A WATER-BASED CLEANER AND A SOLVENT CLEANER

For our discussion, a solvent cleaner or solvent degreaser uses a liquid to dissolve a soil.  It can utilize one solvent, a variety of solvents, or a combination of several solvents and compounds to maximize performance parameters for a specific application.  Solvents can be broken down into their basic functional compounds, such as alcohols, ketones, aliphatic hydrocarbons, etc.  Each chemical category has specific characteristics that lend to different solvency profiles.  The addition of different compounds and mixtures provides the range of solvency seen in commercial products.  These different solvents and cleaning solutions can be tuned to remove a specific soil while leaving other materials relatively untouched. Some familiar solvents include acetone and butyl acetate, which can be found in local hardware stores. Other familiar solvents include alcohols such as isopropanol and ethanol, and even gasoline due to its hydrocarbon composition. 

Water is also a solvent and is a subsection of the solvent category.  Water-based degreasers utilize water as the primary solvent, but can also include any of the solvents mentioned above, plus detergents, pH modifiers, builders, chelating agents, and a variety of other compounds.  When these other compounds are used, water-based cleaners can either be very strong cleaners or mild cleaners.  They can be dangerous or relatively nontoxic, but they usually require a rinse step.  The variety and complexity of water-based cleaners is enormous. The two cleaners are used in a variety of applications which include, but are not limited to, degreasing, precision cleaning, ultrasonic cleaning, and medical device assembly cleaning.

SOLVENT CLEANERS

All solvents work by dissolving the soil; breaking it down into smaller particles and carrying it into the solution and away from the surface being cleaned. Many solvents offer the advantage of quick cleaning, so the soils dissolve and flow off of the substrate without needing extended prep time, processing time, or drying time.

Solvent-based cleaners remain popular in industrial applications due to their cleaning power; they remove thick, baked on oils, dirt, containments, solder flux, and greases. Some examples of strong cleaning solvents are acetone, methyl ethyl ketone, toluene, nPB, and trichloroethylene (TCE). Common mild solvents include isopropyl alcohol, glycerin, and propylene glycol.  In this case, the terms “strong” and “mild” are arbitrary designations. Solvent strength depends not only on the nature of the soils being removed, but also on the amount of soil to be removed and the level of cleanliness that is required.

Solvent-based cleaners can be fast evaporating or slow evaporating, high in odor or low in odor, plastic safe or very aggressive.  The wide array of solvents has allowed the creation of very specific cleaning chemistries for removing specific soils from substrates. For example, some cleaners are capable of removing a specific ink on a plastic substrate while leaving others completely untouched.

FLAMMABLE SOLVENTS VERSUS NONFLAMMABLE SOLVENTS

When choosing a solvent cleaner, one of the first questions is, “should I use a flammable or nonflammable solution?”  If flammable solvents can be safely used and there are no ignition sources, there is good air turnover, and all safety protocols can be followed, flammable solvents tend to be significantly less expensive than nonflammable solvents.  However, if any of the aforementioned safety concerns are an issue, there are many nonflammable solvents to choose from.

EVAPORATION RATE OF SOLVENTS

Solvent evaporation rates vary -- some are immediately volatile at room temperature, while others may only evaporate at elevated temperatures.  Those which evaporate immediately may be better suited to minimizing process downtime, while those that evaporate much more slowly are better suited to elevated temperature soak applications.  There is not a single solvent that works for all applications.  Also, those that evaporate more slowly are less likely to be volatile organic compounds (VOCs) but may need an additional drying process.

SURFACE TENSION OF SOLVENTS

Surface tension is the measurement of a liquid’s ability to pull together into a cohesive droplet.  The lower the surface tension of a material, the harder it is for that material to pull together into a droplet, thus allowing the material to spread out and wet a surface, and ultimately lay down a thin even coat.  When the surface tension is high, the liquid tends to pull together to form droplets.  In general, solvents tend to offer lower surface tension than water-based cleaners, providing the ability to permeate into tight clearance areas to remove soils, without being entrapped.

SAFETY CONCERNS OF SOLVENT CLEANERS

All solvents and cleaners should be handled while using personal protective equipment in well-ventilated areas to minimize exposure. Follow the recommendations offered by the manufacturer’s SDS. 

A growing concern with many solvents is whether they contain Volatile Organic Compounds or VOCs. VOCs are materials that readily evaporate and turn into the gaseous state at normal room temperatures, and their ability to contribute to smog formation and the environmental and personal health impacts associated with them.  This is one reason why low or no VOC solvents are becoming such an important issue as companies are using them to both meet air quality standards and improve worker safety. 

There are a variety of tradeoffs that can accompany the use of solvents that do not contain VOCs.  One downside is the possible increase in the drying time of the cleaners.  This is the case for both water-based and solvent-based systems.  One way to decrease the VOC impact of a cleaner is to add slow-evaporating solvents to the mixture that minimize the VOC contribution to the environment.  This can be the addition of certain materials that act like oils, or in some cases adding water mixtures to the cleaner.  In either case, additional processes including rinsing, drying heat tunnels, or reclamation procedures may be required to meet the required process parameters.

Another tradeoff can be the use of VOC exempt materials, such as acetone, siloxanes, and PCBTF.  While these solvents are generally strong cleaners, they are flammable and the acetone and PCBTF have high odor levels.  Acetone is a relatively inexpensive material, but the PCBTF and siloxanes solvents are much more costly.  Other VOC exempt materials, such as HFC-43-10mee, do not have sufficient cleaning ability to remove most soils when used by itself and must be mixed with other stronger solvents to increase the cleaning ability.

WATER-BASED CLEANERS

Water-based cleaners remove soils not only by dissolving contaminants, but also by chemically reacting with the contaminants to make them more readily dissolvable in water.  For example, some materials will react with or dissolve more readily into an acidic solution (pH of 7 or lower).  Some common acidic materials can be found in lemons (citric acid), vinegar (acetic acid), soft drinks (carbonic and phosphoric acid) and car batteries (sulfuric acid).  Other materials are more readily reacted with or dissolved into a solution with a pH above 7.  These solutions are caustic, or alkaline. Some common caustic materials are ammonia, bleach (sodium hypochlorite), lye (sodium hydroxide), and oven cleaners (more sodium hydroxide).

Most aqueous cleaners contain a variety of other components to enhance the cleaning profile.  These other materials can include[2]:

1. Detergents or surfactants – materials that have wetting and emulsifying properties, and can carry soils into a solution that they would not otherwise dissolve into.

2. Builders – materials that increase the efficacy of detergents in water by adding alkalinity to solutions.

3. Emulsifiers – liquids that can carry oils into water solutions, creating a liquid in liquid solution.

4. Saponifiers – materials that will react with fatty acids and other carboxyl groups to form water-soluble soaps that can dissolve into the water solution.

5. Sequestering agents – bind with calcium, magnesium and other metals in hard water that detract from the overall cleaning ability of the cleaner. Sequestering agents can bind with more than one metal ion at a time.[3]

6. Chelating agents – similar to sequestering agents, but bind to one metal ion only.

The combination of water, solvents, surfactants, and saponifiers can be as effective as solvent cleaning, but often requires a change in the cleaning process. In a high precision application where residues cannot be tolerated, a rinsing process is often required with water-based chemistries. Batch or in-line cleaning systems generally have rinse and dry cycles to overcome these issues.

DIFFERENCES WHEN USING WATER-BASED CLEANERS

Aqueous cleaners can achieve very similar cleaning levels as solvent-based cleaning chemistries, but there are certain differences:

1. Evaporation: Water-based cleaners function in a much narrower range of evaporation time when compared to solvent cleaners.  While solvent cleaners evaporation time can range from milliseconds to months, water-based degreasers usually operate in a much narrower range.  They typically are not left to evaporate on their own, and can normally be used in a cold or hot soak application.

2. Temperature profile:  Cleaning temperatures for water-based chemistries can range from room temperature up to about 80C, depending on the specific cleaner and its formulation.  Although this provides a great deal of process variability, this is much more limited when compared to solvent cleaners. Solvent temperature cleaning range can be much wider just based on the variety of solvents available, from below 0C to above 200C.
   

3. Higher surface tension: In general, water-based cleaners have higher surface tensions when compared to solvents.  Raising the temperature, using different surfactants and emulsifiers, and incorporating spray and drying systems can overcome much of this shortcoming.  However, for the tightest clearance areas, solvents with low surface tension are superior in their abilities to wet into and evaporate out of tight spaces.
   

4. Reactive additives: Some of the reactive additives incorporated into aqueous cleaners can be very aggressive to different metals, plastics, or inks.  Once the part is cleaned, validation of material compatibility with the parts must be checked.  This includes making sure no reactive material is left behind from the rinse process, and verifying that the product will function in the expected manner and in all expected environments.  Trace quantities of some of these reactive materials may contribute to electrical leakage, coating dewetting, and a variety of other defects.
   

5. Rinse and Drying: As noted above, rinsing and drying removes any cleaner components and solubilized contaminants.  While some solvent cleaning systems also require a rinse and dry process, water-based systems are usually more involved with respect to the rinse and dry process in the context of vapor degreasing applications.
   

6. Environmental Impact:  Here again, environmental impact concerns apply to both solvent and aqueous cleaners. Global, national, state and municipal regulations continue to limit the cleaning choices available to manufacturers:
   

• Montreal and Kyoto protocols limit categories of substances like CFC’s (chlorofluorocarbons), HCFC’s (hydrochlorofluorocarbons), and HFC’s (hydrofluorocarbons) due to ozone depletion, global warming, and other environmental concerns.
  

• EPA (Environmental Protection Agency) and state agencies like Cal-OSHA (California OSHA) limit personnel exposure to toxic chemicals.
  

• CARB (California Air Review Board) restricts smog-producing VOCs (volatile organic compounds) in cleaners based on specific cleaning categories.
  

• Hazardous Air Pollutants (HAPs). Hazardous air pollutants (HAPs) are those pollutants that are known or suspected to cause either environmental damage or other serious health effects (i.e. reproductive complications,birth defects, and cancer).[4]  Some solvents are considered a HAP, and in general water-based chemistries do not contain HAPs.
  

• Priority Pollutant List[5]. These are a set of chemicals that the EPA regulates, and has analytical test methods for detecting under the Clean Water Act.  Once again, several solvents are on this list, while aqueous cleaning chemistries are not. 

These regulatory pressures force manufacturers to evaluate new cleaners and cleaning processes to overcome policy-related hurdles. As a result, water-based cleaners are becoming more common in the industry.

WHICH CLEANING CHEMISTRY IS BEST FOR YOU?

Both cleaning technologies have the potential to be very effective in terms of performance – however, the cleaning ability depends on what is being cleaned off of the surface, the substrate being cleaned, and both the process constraints and requirements. All three parameters must work in tandem for the best cleaning results. 

To choose between an aqueous cleaner vs. a solvent, one must evaluate your unique application, requirements, and goals. Then, you must consider safety, performance, and cost of the solution. A good cleaning agent that is made specifically for removing handling soils may not remove machine greases, a cleaner that works well on stainless steel may not be compatible with glass lenses, and a cleaner that removes machining oil may not be clean enough for a liquid oxygen line.

The bottom line is that it’s impossible to make an overall credible judgment of the superiority of either solvent or water-based cleaners without evaluating the unique situation of the user. Luckily, even with the ever-mounting regulations, there's an array of choices that include both solvents and water-based cleaners. 

There you have it - our comparison of solvent and aqueous cleaners. Be sure to post your questions and comments below. And if you still need assistance choosing between a solvent cleaner and water base, speak with one of our product specialists. They’ll help you get the right product for your application.

[1] From ACGIH website, https://www.acgih.org/about-us/history, accessed 07-20-.

[2] Adapted from pages 14-16, “The Aqueous Cleaning Handbook”, McLaughlin and Zisman, ISBN 0--7-X, published .

[3] https://www.researchgate.net/post/Is_there_a_difference_between_chelant_and_sequestrant_agents, Accessed 07-31-.

[4] https://www.epa.gov/compliance/national-emission-standards-hazardous-air-pollutants-compliance-monitoring.  Accessed 08-01-.

For more High Purity Chemicalsinformation, please contact us. We will provide professional answers.