Chapter 6. Cleaning and Reusing Equipment

Much modern medical equipment is labeled "disposable." When resources are scarce, this luxury cannot be sustained. On the other hand, safety regarding reuse of equipment is paramount. Patients should not be put at risk either through introducing infections from previously used equipment or by using malfunctioning equipment. This section discusses the reuse, cleaning, and sterilization of equipment, including guidelines and techniques.

Major governments cannot seem to agree on their recommendations in trying to guide health care professionals in the reuse of single-use devices (SUDs). The United States' policy across several agencies is that SUDs can be reused.

A US government panel of experts stated that in resource-scarce situations, equipment and supplies "will be rationed and used in ways consistent with achieving the ultimate goal of saving the most lives (e.g., disposable supplies may be reused)." However, they also said guidelines are needed on "how to use and reuse common supplies and equipment, such as gloves, gowns, and masks."1

The US Food and Drug Administration (FDA) found that "no data to indicate that people are being injured or put at increased risk by the reuse of SUDs,"2 while acknowledging that many SUDs are commonly being reused. Among these are many types of equipment, including those used in dentistry, orthodontics, otolaryngology, and laparoscopy. Specific equipment being reused also includes needles, scalpels, forceps, trocars, saw blades, staplers, drills, scissors, masks, syringes, gowns, and biopsy devices.3,4 The problems they found with reusing SUDs include a "loss of elasticity in inflatable balloons, persistence of blood and biofilms, loss of original lubricants and resultant effect on catheter threading, and crystallization of liquid x-ray contrast material."4

The US Centers for Disease Control and Prevention (CDC) states that "in general, reusable medical devices or patient-care equipment that enters normally sterile tissue or the vascular system or through which blood flows should be sterilized before each use."5 Except in rare and special instances, items that do not ordinarily touch the patient or that touch only intact skin are not involved in disease transmission and generally do not necessitate disinfection between uses on different patients. Special rules apply when patients are infected or colonized with drug-resistant or highly virulent microorganisms. In these cases, the CDC recommends that noncritical items be dedicated to one patient or patient cohort (someone with the same contagious illness) or that this equipment be subjected to low-level disinfection between patient uses. Reusable items that touch mucous membranes should, at a minimum, receive high-level disinfection between patients.5

The US Government Accounting Office (GAO) concluded that there is no evidence that reprocessed SUDs create an elevated health risk for patients. Testifying before the US Congress, Dr. Kenneth Kizer, a former undersecretary for health at the US Department of Veterans Affairs, said, "Single-use labeling is a real scam for a lot of devices, and by not using reprocessed devices where possible, it is wasteful and not environmentally responsive, since these items have to be disposed of as biomedical waste."6

Members of the European Community have multiple conflicting policies on reusing SUDs, with some allowing it, others regulating it, and some banning it.7

The infection risk that medical equipment poses to patients differs, and can be stratified according to its use into (a) high risk, (b) intermediate risk, and (c) low risk. Each group, under normal circumstances, has different decontamination requirements.

1. High-risk items (sterilization required) come into close contact with breaks in the skin or mucous membranes or are introduced into a normally sterile body area. These include surgical instruments, needles, and urinary or other catheters.

2. Intermediate-risk items (disinfection required) come into close contact with mucous membranes or are items contaminated with particularly virulent or readily transmissible organisms. This includes most respiratory equipment, for example, laryngoscope blades, endotracheal and tracheostomy tubes, and oropharyngeal and nasal airways.

3. Low-risk items (cleaning required) come into contact only with normal intact skin. These include stethoscopes, other physical examination equipment, stretchers and wheelchairs, and electrocardiogram (ECG) and electroencephalography (EEG) leads.8

Cleaning, disinfection, and sterilization all decontaminate medical equipment. Decontamination is the general term describing any method of reducing the risks of cross infection, that is, passing microbes from one infected person to a previously uninfected person.8

Table 6-1 contains recommended processes that can easily be accomplished in most settings for decontaminating and, then, cleaning different types of medical equipment.

When using chlorine solutions, avoid prolonged exposure of the equipment, as this causes metal to rust and rubber and cloth to deteriorate. To avoid dulling the edges, do not sterilize needles or instruments with a cutting edge at temperatures >160°C.

Cleaning is the process of removing any visible dirt or secretions, including dust, soil, large numbers of microorganisms, and organic matter (e.g., blood, vomit) on which microorganisms grow. Cleaning must be done before equipment is disinfected or sterilized; not doing so can impede effective disinfection or sterilization.8

Especially in austere circumstances, "clean items are sufficient to prevent infection in the majority of cases. For the vast majority of minor cuts and lacerations, clean is fine."10 Note that SUD needles cannot be cleaned adequately.

Method

Cleaning normally involves washing the equipment with detergent (soap) and water.8 (To make soap, see "Soap Production" later in this chapter.) Mix fresh dilute soap solutions (and other disinfectant solutions) every 24 hours and store them in a cool place: bacteria may grow in dilute solutions (but not in concentrated solutions).

Clean equipment immediately after use. First, remove blood and other visible dirt by washing equipment thoroughly with warm water without soap. Then wash thoroughly with warm water and soap, rinse with water, and dry completely. Leave scissors and forceps open while drying.11 Clean surgical instruments with a small brush, such as a soft toothbrush.12

Maintenance and Packing

Once the equipment is clean, perform any necessary maintenance (e.g., tighten screws, sharpen edges) and pack them for use or prepare them for disinfection or sterilization.

Disinfection is a process used to reduce the number of microorganisms, although not usually bacterial spores. The process does not necessarily kill or remove all microorganisms, but simply reduces their number to a level that is not harmful to health.8 There are three levels of disinfection: high, intermediate, and low.5

High-level disinfection methods kill all organisms, except when there are large numbers of bacterial spores, through the use of a chemical germicide such as bleach or ethyl alcohol. Intermediate-level disinfection procedures kill mycobacteria, bacteria, and most viruses by using a chemical germicide registered as a "tuberculocide" by the US Environmental Protection Agency. Low-level disinfection kills some viruses and bacteria by using a chemical germicide such as soap.

Usefulness

While the effectiveness of disinfection depends on the method and the disinfectant that are used, some general principles apply8:

• Gram-positive bacteria are more sensitive than gram-negative bacteria.
• Mycobacteria and spores are relatively resistant.
• Non-enveloped viruses, such as Coxsackie, tend to be more resistant.
• Fungal spores can be killed by disinfectants. Other bacterial spores, such as Clostridia, are generally resistant.
• Tubercle bacteria (TB and related organisms) are more resistant to chemical disinfectants than other bacteria.
• Many common pathogenic viruses can be inactivated by exposing them for 10 minutes to 70% alcohol or for 30 minutes to 5.25% sodium hypochlorite (bleach). These include HBV (hepatitis B) and HIV (human immunodeficiency virus), as well as the viruses that cause rabies, Lassa fever, and other hemorrhagic fevers.

Methods

While chemical disinfectants are the norm, in austere environments, disinfection is best achieved by using boiling water, with or without soap. Heat disinfection is more effective than chemicals. At 80°C, most bacteria (but not their spores) will be destroyed within a few minutes. Boiling accelerates rusting of items with a sharp edge, such as scissors and knives. Using distilled or soft water reduces this problem.

Washing instruments in soap solution and then boiling for some minutes in water is an effective method of disinfection.13 Various concentrations of soap solution may also be used to wash hands and operating fields before surgery, to wash bedding and clothes, and for personal hygiene.

Boiling

The general rule is to boil contaminated equipment in clean water (100°C [212°F] for 10 to 30 minutes at sea level). This kills all organisms except for a few bacterial spores. Do not start timing it until the water has come to a full boil. At higher altitudes, the temperature at which water boils decreases, so a longer boiling time is required. In theory, the time should be increased by 5 minutes for each 300-meter (1000-foot) rise in altitude.14 For example, at 4000 meters (~12,000 feet) above sea level, water boils at 86°C (187°F), so ≥60 minutes is required for disinfection.

A way to increase the disinfectant effect of boiling is to use "double boiling." Boil the instruments for 30 to 40 minutes. Let them cool and then boil for another 30 to 40 minutes.15

Various techniques can be improvised to boil medical equipment, including using a sieve, a vegetable steamer, or a sling.16 To use a sieve (or colander), place the instruments in it and put it into a pan of boiling water. When the time has elapsed, lift the sieve out and let everything air dry. With a vegetable steamer, place the instruments in it, cover it tightly, and steam the instruments. Then drain the water and the instruments can cool without being touched. Alternatively, use a sling made from gauze or other thin material. Stretch a piece of gauze, in the form of a hammock, over a pot and tie the ends to the handles. Place wrapped equipment in the hammock and put a tight-fitting lid on the pot. When finished boiling (this takes more time, up to 4 hours, since the equipment is sealed in packages), transfer the packages to a baking pan or an oven grate wrapped in heavy paper for drying. A net bag can also be used to suspend wrapped or unwrapped small equipment in a pot.

Chemicals

There are a number of chemical disinfectants available, even in austere environments. To disinfect against different organisms, the equipment must be immersed in the chemical for the appropriate amount of time.

Hypochlorite Solutions

Hypochlorite (e.g., bleach) in varying concentrations has a wide range of activity against bacteria, fungi, viruses, and bacterial spores. It is an effective disinfectant, both for equipment and for medical areas such as operating rooms.

Thoroughly clean equipment before using bleach as a disinfectant, since its activity is reduced by the presence of a biofilm or organic material. Since bleach is corrosive to metal instruments, don't leave instruments in the solution longer than 30 minutes. As soon as they are removed, rinse and dry them.

In health care facilities, (Table 6-2) bleach is used to clean environmental surfaces, disinfect laundry and equipment, decontaminate blood spills, and decontaminate medical waste prior to disposal. Bleach has also been recommended as a good way for IV drug addicts to clean needles for reuse (see "Needles" in this chapter). In the past, health care workers used bleach to clean their hands.17

Alcohols

Alcohols (e.g., methanol, ethanol, and isopropanol) are active against bacteria and viruses. When an alcohol solution of ≥70% concentration is used, immerse the equipment in the solution for ≥10 minutes, and for 12 hours or more, if possible.18 As with bleach, use alcohol as a disinfectant only after equipment has been cleaned—or, at least after all the visible surface dirt has been removed from the area to be disinfected.8 To prepare a 70% ethanol solution, add 8 parts 90% ethanol to 2 parts water. To prepare a 70% isopropanol solution, add 7 parts standard isopropanol to 3 parts water.14

Aldehydes

Aldehydes (e.g., formaldehyde) are potent and potentially dangerous chemicals. Formaldehyde, usually available wherever a laboratory or mortuary exists, is active against bacteria, viruses, and fungi, but has a slow action against tubercle bacilli.8 Prepare an aldehyde disinfectant solution by adding 1 part 4% formaldehyde to 3 parts water. Soak instruments for 30 minutes or, if they were used on infected patients, for 1 hour before drying and sterilizing.11,14

Povidone-Iodine

Povidone-iodine (PVP; Betadine) may be used for disinfecting instruments if nothing else is available. While exact information about this is sketchy, studies seem to support its use. The recommendation is to add 1 part 10% povidone-iodine solution to 3 parts water and soak instruments for 15 minutes.14

Sterilization removes or destroys all forms of microbial life, including bacterial spores.8

Methods

There are several methods for sterilization, but only the methods using heat are useful in austere environments. Clean and open instruments, then wrap them in paper (including newspaper) or tightly woven cloth. Double wrapping generally gives the equipment a shelf life of several weeks. The ideal wrap is a layer of cloth inside a paper cover.14 If instruments or cloth packs are kept in metal boxes for autoclaving, the boxes must have multiple holes in the bottom to let the dry air "run out" of the box.15

Moist Heat: Pressure Cooker

Moist heat is the most effective method for sterilization in austere situations, although the necessary equipment may not be available.

If you can find one, a home pressure cooker will sterilize medical equipment very well. (Note that this is not a "double-boiler," but a sealed cooker with a pressure gauge, such as those used for home canning. The combination of steam and pressure sterilizes the equipment.) Home pressure cookers do not have a thermometer: use time and the pressure gauge to decide when sterilization is complete. Generally, you should boil items for at least 30 minutes under 3 to 5 pounds pressure.16 For an extra measure of safety, add another 30 minutes.

To sterilize equipment using a pressure cooker15:

1. Add water, preferably distilled or fresh rainwater to lessen mineral deposits that have to be cleaned off. Add enough water so the cooker won't run dry during the process.

2. Put the equipment on the pressure cooker tray over the water and close the lid. Do not stuff the equipment in; the steam must circulate to be effective. Put any metal container containing equipment on its side with the top removed, so the steam will circulate.

3. Open the valve and apply heat. Bring the cooker to a full boil. It will begin whistling like a tea kettle when ready. When it stops expelling air and water from the valve, close it.

4. Only at that point should you begin timing. (The sterilization process will be ineffective if you begin timing before it is boiling.)

5. Once the process is done, take the cooker off the heat and, when it has cooled and the steam is out, open the valve. Unlock the cooker and let the equipment dry by evaporation as it cools. Equipment packs may need to be placed on a drying rack. The time required to cool off depends on the material, but usually is at least 30 minutes. Glass and culture media can take several hours to cool. To cool the equipment quickly, run cool (sterile) water over it. Caution: this may cause any glass to shatter.

6. Clean the pressure cooker with distilled water or fresh rainwater after each use; do not use detergents. Check the gasket, pressure vent, gauge, and other parts; you don't want it to explode on you. If the cooker has a manual, read it to determine any special maintenance requirements, time variations for sterilization, how much water to add, and how to tell when it is safe to open it.14

Dry Heat

Oven

An oven is normally used for hot air sterilization, but this takes a long time. Equipment must be able to withstand temperatures of at least 160°C (320°F) for 120 minutes or 170°C (340°F) for 60 minutes.19 Do not start timing until the desired temperature has been reached. Be careful not to exceed 170°C (340°F) or metal instruments may be damaged.

To eliminate most moisture and decrease the chance of metal equipment rusting, leave the door open for a few minutes while heating the oven. Use this method for surgical instruments and high-temperature glass or plastics, but not for textiles. (See "Dressings and Other Textiles" later in this chapter.) Heat the oven to 160°C (320°F) to disinfect oils, ointments, waxes, and powders. Bake them for 2 hours.

Fire

Equipment "soused" and "flambé" are two common methods to quickly disinfect small metallic medical equipment in austere settings. The recipients of this affection are usually pins (e.g., to trephine nails or open blisters), knives (e.g., to incise and drain abscesses or remove foreign bodies), and needles (e.g., to suture or remove foreign bodies). Dip the instrument in alcohol, preferably the highest concentration available, and set fire to it. This is not a completely reliable sterilization method and will damage the instruments. If alcohol is not available, heat the "business end" of the instrument with an open flame until it glows red. This is an effective sterilization method, but it will also damage any instrument on which it is used.14

Syringes

There are two types of syringes: disposable and reusable. The main differences relate to the material used to make the barrel and plunger of the syringe.

Reusable Syringes

A reusable syringe's body and plunger are made of either glass or a plastic that can be autoclaved. Even though these instruments may sometimes be called "permanent," autoclaving eventually breaks down the rubber on a "reusable" plastic plunger and the glazing on the glass plunger wears out.10

Sterilization

The best method to sterilize syringes is to use a rack to suspend the barrel and plunger. The World Health Organization (WHO) reports a 40% failure rate with other methods—probably because the syringe surfaces in contact with the tray are not accessible to the steam; thus, some organisms survive.

Make a holder by bending metal in an "S" configuration so that the syringe bodies, plungers, and needles can be suspended with minimal contact with the rack itself; they should hang freely. Be sure to take the plungers out of the syringes or they may break.

An alternate sterilization method is to wrap the plungers and cylinders in an operating room (OR) towel and push the needles through the cloth. No item should be in contact with another. Fold to make a pack and autoclave, or use a pressure cooker as described previously.10

Single-Use Syringes

The danger of reusing syringes, even though this practice is common throughout the world, appears to negate any good produced by medical treatment. Every year the reuse of dirty syringes infects millions of people with AIDS and hepatitis and "causes 1.3 million early deaths, a loss of 26 million years of life, and an annual burden of US $535 million in direct medical costs."20 Young adults are most affected.

If you still plan on trying to sterilize disposable syringes, understand that they will generally melt when heated to sterilizing temperatures, but they can be autoclaved several times before deforming beyond usefulness.10

Needles

Reusable Needles

Reusable needles generally have a Luer lock attachment to fasten to the syringe (as do many disposable ones) and are made of a harder metal than the disposable needles so that they can be sharpened. They also come with a needle plunger so anything trapped in the needle cylinder can be removed.10

Sharpening Permanent Needles

According to the editors of Survival and Austere Medicine, this is how to sharpen a permanent needle10: Place a drop of light oil (sewing machine, light machine, or gun oil) on a fine sharpening stone. Draw the bevel of the needle (flat part of tip) back and forth at a uniform angle with no rocking. The goal is to keep the bevel the same length as on a new needle. Any rocking side to side will cause the bevel to become rounded, which need to be corrected. Changing the angle of attack against the stone will cause, at best, a dull needle and, at worst, a hook on the point. After sharpening for a bit, a burr will form on the sides of the bevel—this is a thin edge of metal. Remove it by gently drawing the needle on the side to the top, forming two facets along the top of the point.

Always finish by giving one rub along the bevel and one to each facet. When finished, check it with a magnifying glass. Needles should be soaked overnight in trichloroethylene to remove any oil. Then, polish with a soft cloth and push water through the needle to make sure the cylinder is clear. If you do not have access to oil and a solvent to remove it, then sharpen and clean the needle using hot soapy water (including inside the barrel using fine wire). This procedure should be done only when the needle seems to be getting dull, not after every use.10 Maurice King's A Medical Laboratory for Developing Countries (Oxford University Press, 1973) contains more complete instructions and good illustrations.

Single-Use Needle on Same Patient

Patients with diabetes routinely reuse the same syringe for up to one week, which is fine if it is kept in a clean container. During this time, they do not decontaminate the syringe. Likewise, in situations of scarcity, a needle should be able to be used on the same patient over a short time period (e.g., 1 week). This assumes that care will be taken to keep the needle clean and that it won't be used on anyone else.10

Reuse of SUD Needles

Unsterilized SUD needles are responsible for 1.3 million deaths per year, mostly in developing countries.21 In addition, it is estimated that 160,000 new HIV infections and millions of new cases of hepatitis B and C are caused each year from the use of dirty needles.22

Disinfection Method for Needles and Syringes

It is optimal either (a) to administer medications other than by injection when appropriate or (b) to use reusable needles with appropriate sterilization or new SUD needles when possible. When no other option exists, use high-level disinfection to make SUD needles and syringes as safe as possible. US governmental agencies recommend that needles and syringes potentially contaminated with HIV virus should be thoroughly cleaned and then immersed in full-strength bleach (5.25% sodium hypochlorite). They recommend using full-strength bleach because of the difficulty of cleaning the interior of needles and syringes for parenteral injection.17

Respiratory, Anesthesia, and Resuscitation Equipment

In general, it is unnecessary to sterilize respiratory and anesthetic equipment, since spore-bearing organisms are not a cause of respiratory infections.8 High-level disinfection, or even a lower level of decontamination, often suffices.

Anesthesia Equipment

The internal circuit in mechanical ventilators can often be autoclaved. The external (or patient) circuit should be changed every 48 hours or between patients. Both the external circuit and the humidifiers require high-level disinfecting. Heated-water humidifiers, however, need only be cleaned, dried, and refilled with sterile water every 48 to 72 hours.8

Nebulizers should be cleaned and rinsed in alcohol every 48 hours.

Resuscitation/Respiratory Equipment

Bag-valve-masks (BVMs) should be washed and cleaned as soon as possible after each use. Laryngoscope blades should be washed after each use, ideally using hot, soapy water to remove secretions. A surgical brush helps to clean the blade. High-level disinfection should follow.23

SUD endotracheal tubes can be reused if they are cleaned and given high-level disinfection. Note that using heat will probably damage them, so immerse them in a 70% alcohol solution for 10 minutes. Allow the tubes to dry before reuse.8

Suction catheters can be difficult to clean. The best method is to suction clean water through them. Then use a high-level disinfectant and allow them to air dry before reuse.

Surgical Instruments

Sharp/Delicate Instruments

Sharp or delicate instruments should be chemically sterilized using alcohol. Acetone can also be used if the equipment does not contain plastic or polymers. Rinse them in hot, sterile water and let them dry before reuse.12

Lightweight Surgical Instruments

Lightweight surgical instruments, such as ophthalmic or plastic instruments, can be sterilized in a pressure cooker or autoclave. Heavier surgical instruments (without a fine tolerance or sharp edges), such as mosquito clamps, towel clips, and large needle holders, may be disinfected in boiling water.12

Endoscopic Equipment

Laparoscopic or arthroscopic telescopes (optic portions of the endoscopic set) should be sterilized before each use. If this is not feasible, use high-level disinfection. Sterilize heat-stable endoscopic accessories, such as trocars, using an autoclave/pressure cooker or dry-heat oven.5

Dressings and Other Textiles

Disinfection can be accomplished with the following methods10,14:

• Ironing: Cover a table with a cloth that has previously been ironed. Then, dampen that cloth and the one to be disinfected with boiling water and press with a very hot iron for several passes. Steam as you iron.
• Solar: Hang the textile in full sunlight for 6 hours per side.
• Washing: When dressings are in short supply, they can be disinfected by (a) washing and then boiling them for 5 minutes or (b) washing, rinsing, and then soaking them for 30 minutes in a 0.1% chlorine solution or a 5% Lysol solution.

"Sterile" Dressings

Cloth for a dressing can be cleaned and disinfected by boiling it in water for 15 minutes or by saturating it with alcohol. It can also be sterilized using any of the sterilization methods described previously. Normally, clean and disinfected is sufficient. If using dry-heat (oven) sterilization, remember that the exact time and temperature required will vary according to the volume of material treated, volume of the autoclave, contamination level, and moisture content of the cloth: the minimum is 160°C to 170°C (320°F to 340°F) for 2 to 4 hours.24

When reusing dressings (common in austere battlefield conditions), wash the gauze dressings (or immerse in saline) to remove stains, dry them, and then sterilize using dry heat.25

For ease of use and to make sterilization easier, wrap dressings in aluminum foil and place the package on a flat pan in the oven. Bake at 350°F (177°C) for 3 hours. When they have cooled, label each dressing with its size.26

Gloves, Tubing, and Plastic Items

Gloves

While disposable gloves are preferred, they may not be available—or may be too expensive to use only once. Single-use surgical gloves may be reused up to three times if they are not obviously torn. After that, additional autoclaving breaks down the rubber and the gloves develop microscopic tears that put the patient and clinician at risk.

To prepare disposable gloves for reuse, first blow into them to ensure they do not leak. If there are holes, patch them from the inside. Next, decontaminate the gloves by soaking in a 0.5% chlorine solution for 10 minutes, or simply wash and rinse them. Cover the inside with talcum powder and let them dry thoroughly; otherwise, they will stick together and be unusable. Sterilize by autoclaving or perform high-level disinfection using steam or boiling.27

Rubber and Plastic

Rubber and plastic deteriorate with repeated sterilization. Wash all tubes, catheters, gloves, and other rubber or plastic equipment for reuse in cold water immediately after use, next wash in warm water with soap, and, finally, rinse in water. Dry rubber equipment thoroughly. It sticks to itself and becomes damaged if stored moist.28

Plastic Items (Airways, Syringes, and the Like)

How to sterilize plastic equipment depends on the type of plastic.10 Unfortunately, that may be difficult to discern. General guidelines are as follows:

• HDPE (high-density polyethylene): Translucent. Autoclave at 121°C (250°F) for no more than 15 minutes.
• PP (polypropylene): Translucent. Autoclave at 121°C (250°F).
• PMP (polymethylpentene): Clear, brittle at room temperature, can crack or break if dropped. Autoclave at 121°C (250°F).
• PC (polycarbonate): Clear. Autoclave at 121°C (250°F).
• PTFE (polytetrafluoroethylene): Not translucent. Autoclave at 121°C (250°F) or put in oven at 160°C (320°F) for 2 hours or 170°C (340°F) for 1 hour.

Glassware

In general, clean and then sterilize glassware used for laboratory or patient care. Use a pressure cooker or autoclave. However, note that glassware can crack or shatter if the autoclave or pressure cooker is opened too soon or if cool water is poured over hot glass (known as speed cooling). Also, some glassware, especially pipettes, may not fit in a pressure cooker.

Soap is generally available, and cheap, in most places. Sometimes you may have to make your own. A very basic recipe for hand soap is

• 0.50 ounce (oz) (14 g) lye
• 0.25 cup cold water
• 0.50 cup lukewarm fat
• 1 Tablespoon lemon juice (optional)

In a plastic container, gently stir the lye into cold water with a wooden spoon. Slowly add lukewarm fat. Continue to stir until slightly thickened. Add lemon juice, stirring to mix thoroughly. Pour mixture into plastic molds. Cover with plastic wrap and leave for 24 hours. Remove soap from molds and allow to air dry for 14 days. This will make 1 to 2 medium-sized bars.

The details of making soap, including methods to make liquid, hard, and even "smelly" soap, can be found at: http://www.folksonline.com/folks/hh/tours/soapmkg.htm.