by Gord

Chlorination - a surface treatment for rubber.

Exposing latex rubber to chlorine gas causes the chlorine to attach to sites on the rubber molecules, which has the effect of reducing the friction at the surface of the rubber. In practical terms, rubber garments which have been properly chlorinated are much smoother and can usually be worn without the need for talc or other lubricants. This document sets out to describe a process for chlorination of rubber garments, together with safety notes and other possible methods.

WARNING

The chlorination process described below involves the use of dangerous chemical solutions and a toxic gas. Anyone attempting to perform the process should be aware of:

The inherent risks

Handling procedures of dangerous chemicals

Disposal of chemical wastes

Procedures involving toxic gases

These are reviewed in Appendix I

Objectives

A properly chlorinated rubber cat suit is a delight to put on, wear and take off. Chlorination normally dispenses with the need of talc or lubricants and the inherent costs, maintenance, time and cleaning, and obviates the production of talcum-laden sweat dripping white stains everywhere. In storage, the rubber does not stick to itself and when worn there is far less noise/squeaking from the material, hence the nickname "stealth latex"!

There is a number of techniques for chlorinating rubber garments; the following is widely regarded as the most successful, provided the warnings are heeded. Other methods are reviewed in Appendix II

Appendix III lists references.

Method outline

The rubber garment should be clean and free from body oils, silicones etc. Methods of cleaning are outside the scope of this document.

Household bleach is added to a bucket of water, then acid is added to produce chlorine gas. (Acid and bleach should be handled with care; the resulting chlorine gas should not be inhaled.)

The rubber garment is plunged into the bucket and agitated for a short while.

The garment is turned inside-out and agitated in the bucket again.

After four minutes, the garment is removed and rinsed twice in clean water.

The garment is dried then worn. The effect will be noticeable at once and is widely regarded as amazing!

Chemistry and the Chlorination Process

Latex rubber molecules are complex organic polymers arranged in coiled chains, and loosely bonded to one another in three dimensions to form a continuous elastic sheet. Molecules at the surface of the sheet can only bond to those inside the sheet, not to thin air! This leaves the surface molecules with vacant bonding sites and may be the origin of the micro-roughness that causes the high friction associated with rubber. Garments from such material require wet or dry lubrication, such as talcum powder, to enable wearing. However, once the lubricant is washed off, the rubber returns to its high-friction mode again.

The idea of chlorination is to permanently fill the surface irregularities with ions of chlorine, as these will chemically bond to the rubber molecules, filling the dips and resulting in a much smoother surface.

Chlorine gas cannot readily be purchased, so it is necessary to generate the chlorine "in-situ" using household chemicals, commonly bleach and hydrochloric acid. The formula is:

NaOCl + 2HCl > NaCl + H₂O + Cl₂ OR:
Bleach + Hydrochloric Acid gives Salt + Water + Chlorine

You start with 2 strong reagents, in correct proportions, diluted in water, and end up with chlorine gas and neutral salt water. To achieve a neutral end product, it is essential to use the right mix.

Generally, household bleach is 5%, and Hydrochloric acid is 30%. To achieve a neutral end product, they must be mixed in a ratio of 1:6 (or 5:30). To make the process workable for rubber clothing, the reaction is diluted in a large volume of water; typically 1000ml of water with 30ml bleach and 5ml acid.

The reaction is immediate and that half-life is about 90 seconds, that is half the available chlorine gas will be produced in the first minute and a half. After about 4 minutes, most of the useful chlorine will have been produced; little effective chlorination will take place beyond this time.

Rubber garments can then be removed and rinsed, and the spent solution safely poured down a drain1.

Apparatus and reagents

This can be really simple. I do it with 3 large buckets, a garden hosepipe, a 1 litre measuring jug, a small fluid measure (100ml graduated at 5ml intervals) and a windy day2. A fan can be substituted for a windy day if the latter is not readily available.

Tap water, household bleach and hydrochloric acid are the ingredients. The bleach should be "thin" ("less than 5%") and unscented. Hydrochloric acid (a ~32% solution of hydrogen chloride in aqua [water]) is available in hardware shops often under the name of "Spirit of Salts" or "Muriatic Acid"

Rubber gloves should be worn. Respirators capable of removing chlorine will obviate the need for a windy day, but be sure the filter cartridge is appropriate, as chlorine gas is toxic. Other protective gear may be employed as seen fit, such as goggles, apron etc.

A stirring rod with no sharp edges, and a timer of some sort are also required.

Method for first chlorination trial.

Indoors - arrange the equipment and chemicals on a hard, resistant surface near a window (such as a kitchen work top) and position the fan to blow air from the operator, across the work area and towards an open window.

Outdoors - arrange everything as above, keeping the wind blowing from behind the operator. Ensure a safe path of exit in case the wind should fail or change direction.

Both locations - Choose a latex garment that is small and can easily be turned inside out such as a pair of briefs. Fill 2 buckets with plain rinse water and place to one side. Place 2 litres of cold water in a third bucket. Put on protective gear. Measure 60ml bleach and add to the water in this bucket. Measure 10ml hydrochloric acid and simultaneously: pour into bucket and stir, start the timer, plunge the garment into the bucket.

Stir for one and a half minutes. Ensure airflow keeps the chlorine gas away. Turn garment inside out and continue stirring up until four minutes. Remove garment and plunge into first rinse bucket. Relax. Stir garment occasionally. After a minute or so, transfer garment to second bucket and rinse as before. After a couple of minutes, remove garment and hang to dry. After half an hour, pour all three buckets' contents away, and recover (now dry) garment. Examine dry garment for smoothness - it will be!

Advice for subsequent chlorination.

Two difficulties will have been appreciated during the trial: how much latex clothing per litre of solution, and how long it takes to turn garments inside out. This experience, plus further trials will give the operator the ability to adjust the method for future needs.

If a garment is not fully chlorinated, or has unchlorinated patches, it will be necessary to check cleanliness, especially silicones, and once clean, re-run the chlorination. It is impossible to over-chlorinate a garment - there is a finite number of sites on the garment's surface available to the chlorine.

Excessive/repeated chlorination may have detrimental effects on glued seams and on the colour dyes used in some materials.

Appendix I Health & Safety

Reagents:Hydrochloric acid - risk - irritation/burns to skin, eyes, mucous membranes.
- damage to metals, carbonate stoneware (e.g. concrete)
- minimisation - use protective clothing
- use respiritory protection
- handle with care - avoid splashes/spills
irrigate splashes with plenty of cold water
seek medical attention if necessary

Bleach - risk - irritation to skin, eyes, mucous membranes
- minimisation - use protective clothing
- use respiritory protection
- handle with care - avoid splashes/spills
irrigate splashes with plenty of cold water
seek medical attention if necessary

Mixing reagents (use inert containers/utensils) *** Toxic Chlorine Gas Produced ***

Chlorine - (Ref 2.) risk - *** Poisonous *** Excess concentrations can be fatal
- irritation to skin, eyes, mucous membranes, respiratory tract
- minimisation - use protective clothing
- use respiritory protection
- use in well ventilated area, with forced-air ventilation if necessary
- handle with care - avoid splashes/spills
irrigate splashes with plenty of cold water
seek medical attention if necessary

Process - adding latex garments to chlorination mix/agitiating/removing

- risks - as 'chlorination' above

Rinsing - transferring chlorinated garments with residual reagents to water rinse.

- risks - as 'chlorination' above, but much diluted so lower risk.

(Ref 1.) Spent reagents. If reagents of correct concentration are mixed in the proportions recommended, after ten minutes the resultant mixture will be salt water with a reasonably neutral pH. If any doubt exists, addition of sodium carbonate solution (washing soda in water) should neutralise any remaining acid, but may also give rise to an alkaline pH value.

Drying rubber. No specific risk identified.

Wearing chlorinated rubber garments
risk - residual active reagents
minimisation - ensure garments are rinsed and dried before use
risk - slipping - beware - chlorinated rubber is very slippy
minimisation - awareness of risk. Wear a belt on your jeans over rubber garments!

Appendix II Alternative Chlorination Methods

Chlorination is all about exposing the surfaces of a rubber garment to chlorine for sufficient time and concentration to allow all the sites on the surface molecules to become occupied by chlorine.

1. The acid/bleach method above is well documented and effective.

2. Acid/bleach may also be attempted in a washing machine. This will help contain the reaction and give good agitation. It may be necessary to turn certain garments inside out and repeat. To avoid damage to the washing machine, add the acid last and do not use the heater.

A washing machine should never be exposed to strong hydrochloric acid, so the main method is not recommended for this usage.

3. Chlorine is also produced at a slower rate from swimming pool chemicals. No advice is available

4. Chlorine is produced at a very slow rate from heating household bleach. Repeated washing of rubber clothing in diluted bleach over an extended period will result in chlorination, or leaving to soak for 24 hours will give at least partial chlorination.

Appendix III Things NOT to do, and potential hazards

Apart from the health and safety notices above, other advice and cautions are offered.

Incorrect ratio of reagents - too much acid may damage glued seams, may harm any skin in contact, may require extra rinsing and the spent solution will be mildly acidic.

Too much bleach is unlikely to pose any serious hazard.

Failure of glued seams - this is not widely reported but may result from excessive re-chlorination

Change of colour has occasionally been reported, normally a slight lightening of shade. Blotchiness often disappears after a few hours.

Surface shine may be slightly affected.

The new slippy surface has many benefits, however be aware that vanilla over-garments such as loose-fitting jeans - which previously stayed in place - are now more likely to slip down - a belt could be required! Likewise soles of feet will become more slippery.

Selective chlorination is worth considering, for example chlorinating the inside only of a catsuit (taping neck/cuffs shut during the process) to make it easy to put on, but not slippery on the outside, or chlorinating the outside only of stockings so they swish nicely, but will hold up by themselves.

Appendix III References and Further Reading

Sources all International Association of Rubberists - http://www.rubberist.net

Specifically: Chlorinating Latex Garmentshttp://www.rubberist.net/forums/forumdisplay.php?f=277 (simple membership may be required)

Gord. August 2005