As a model, as a porn girl, i have to be aware of marks on my body, a clean canvas is so very necessary for work.  Some people may be wary for other reasons.   This article is posted on my web site, and i have copied it here so that the information is more accessible to people.

Overview:

A bruise is a common skin injury that results in a discoloration of the skin. Blood from damaged blood vessels deep beneath the skin collects near the surface of the skin resulting in what we commonly call a black and blue mark.


Causes:

Bruises can easily be the result of erotic power exchange play. For some they are considered nice reminders, marks carried of their Master. For others, bruises are almost a badge of honor, like brownie points. However, others hate them or - for social reasons - do not like them at all. For some bruises must be treated quickly, so that they may work again, as in the case of professional submissive and models.

A bruise will occur after being hit with an instrument. Caning for example will leave fierce and long lasting stripe bruises, or the skin may be broken after a welt is hit. Bruises that are the result of spanking may disappear quickly. Bruises can occur on some people who are made to exercise rigorously, or lift weights. These bruises result from microscopic tears in blood vessels under the skin. There are very little general rules about bruising, since much of this depends on your physique and physical condition. Some medicine - for example aspirin - may even have a "bruise-improving" effect on a person’s body. Drinking alcohol within 24 hours of play will increase bruising.

Less obvious causes of bruising are:

Kneeling and crawling may cause bruises (even when not done across rice grains or legos).

Lying down for a several hours at a time without being able to change position during prolonged bondage or when locked in a cage will cause bruises.

Untying your bondage by pulling away access rope ends you can easily burn the skin in a way that causes rope burn and bruising. A simple prevention is to put two fingers under the rope and letting the end, you want to pull, slip through in between your fingers.

Labia and nipples can and will bruise as well, but due to the dark skin color you may not be able to notice the discoloring. Nipple and labia clamps for example almost always leave bruises; you are just unable to see them.

Physical Prevention:

These are some techniques I use to keep myself less bruised, more clean canvas.  


Something simple like placing a latex sheet over yourself or wearing latex will help to prevent bruising.

The technique in using a cat-whip with broader and more strokes produces a sturdy effect but - since the impact is spread more evenly – and it also prevents bruising. Rounding the tips of the strokes will also help. Wide paddles are less like to bruise than narrow paddles. The suede based floggers are bruisers, and are not as "soft" as you think they are. Deer skin is much softer than elk, moose, bison or cow. Going slow and opting for MANY instead of HARD strokes (which will eventually produce the same effect) will also help you to prevent bruises. That is also true for spanking. A good warm up also helps.

Another prevention tool is the temperature in the room. If it is warm enough, the body will send LESS blood to the skin in an effort to warm it, hence the internal pressure in the capillary is a lot less and there is less risk of the small veins breaking, which is what causes the bruise. Alternatively, if the temperature in the room is to high, the body will also send larger quantities of blood to the skin in an effort to cool it (which is also what the body does during an actual spanking or flogging, this is what colors the skin reddish), hence the capillary pressure again is higher than normal.


Clamps with a broader, flattened beak coated with cork, latex or plastic - are less likely to bruise. Sharp small clamps with little teeth inside bruise more easily. If you are using clothespins, the side of the pin is the cause the bruising. Rounding them off a little with sandpaper helps preventing bruises.

In general, if you have an impact surface that is spread out rather than concentrated to a smaller spot, you bruise less.  It is simple physics: energy force spread over a greater area rather than the same energy force spread on a smaller area, impacts less.

Bruises and sprains

i highly recommend ice packs applied within 24 hours to reduce inflammation and fade marks. Applying for 20 minute periods and off for 20 minutes, a minimum of three times will work wonders.

Comfrey (Symphytum officinale): A poultice of comfrey leaves will reduce bruising and speed healing of sprains and fractures. BUT, it must not be used on deep wounds as comfrey is such a powerful tissue healer that the surface skin may heal before the wound has healed deeper down. Comfrey also encourages good formation of scar tissue.

St John’s wort (Hypericum perforatum) and arnica (Arnica montana): Both are excellent for sprains and bruises, especially if there is any pain or inflammation of the skin. BUT, do not use arnica where the skin is broken.


Calendula (Calendula officinalis) , agrimony (Agrimonia eupatoria) and elder leaves (Sambucus nigra): All are soothing and healing for bruises, sprains and other minor wounds.

Balm of Gilead (Cedronella canariensis): Relieves bruises, cuts and arthritic pain.

Myrtle (Myrtus communis): Aids bruising.

Catnip (Nepeta cataria): Ointment or a poultice containing mashed leaves and flowering tops of catnip soothes external bruises.

Hyssop (Hyssopus officianlis) and Bay (Laurus nobilis): Essential oils of either of these can be gently massaged around sprains and into aching joints or bruises.

Parsley (petroselinum crispum): The juice reduces swelling and its leaves can be used in a poultice as an antiseptic dressing for sprains and wounds.
Distilled witch hazel: Apply with sterile cotton wool as soon as possible to small bumps and bruises to halt swelling.


If you do not grow your own herbs and cannot buy them, you may go to a Whole Foods or Wild Oats Market (these are Health Food chain markets in California) or online to purchase:

Arnica lotion or gel

Traumeel which has arnica montona and calendula as ingrediants.

Herb Pharm brand: Comfrey (liquid herbal extract) and Herbal Ed's Salve which has Comfrey, Calendula, and St. John's Wort.


Inflammation


Marshmallow root or Borage leaf (Boraginaceae): A poultice or ointment containing either of these soothes inflammation and bruising.

Calendula: Oil extracted from the petals is healing and rejuvenating. In particular, it soothes inflammations and cracked skin (especially good on nipples).

Lavender (Lavandula angustifolia): Massage oil containing lavender aids inflammation and rheumatic aches.

Cuts and Abrasions

i have Neosporin in my sub back to apply immediately on cuts after play.

Witch hazel, thyme, rosemary and calendula: Clean any cuts by soaking in witch hazel diluted with 4 parts water, or use 3 drops thyme or rosemary oil or one half a teaspoon tincture of calendula to 1 cup of hand-hot boiled water. These antiseptic washes can also be gently swabbed with a series of sterile cotton-wool.

Lady’s mantle (Alchemilla vulgaris): An infusion of lady’s mantle can be used as a compress to arrest bleeding, heal wounds and reduce inflammation.

Comfrey, self-heal (Prunella vulgaris) Chamomile (Chamaemelum nobile) and yarrow (Achillea millefolium): For slow-healing wounds apply a compress or poultice of comfrey (BUT see above regarding its effects on deep wounds). Compresses or ointments containing self-heal, chamomile or yarrow are beneficial

.
Plaintain leaves (Plantago major): These have antibiotic properties.

Tea Plant: Tea plant ointment is a good antiseptic.

Comfrey, calendula and agrimony: To continue treatment, a soft ointment containing any of these is soothing and healing.



NOTE: If applying a poultice to an open wound, dip the leaves briefly in boiling water to sterilize them.

Minor Burns

Aloe Vera: Immediately apply the cool inside surface of an aloe vera leaf to reduce pain, speed healing and leave a protective seal against infection. Crush the sap from fresh aloe vera leaves or slice them and apply as a poultice. For small burns, break off a leaf and apply the sap; for larger burns split and open out the leaf, place the sap against damaged skin and lightly bandage
in place, renewing as necessary.

Calendula: Applied as a cool compress or ointment, it soothes and heals.

Marsh mallow(Althaea officinalis): Added to an ointment, it will soothe minor burns.


Circulation

Rosemary (Rosmarinus officinalis): The leaf stimulates circulation and eases pain by increasing blood supply where applied. It can also be good for aching joints and rheumatic pains.





Ending thoughts:


A bruise is there to tell you that the bruised area requires healing before it can be used for similar activity again and the physical signs (discoloring) will act as an alert to not use that area again until the marks/bruises/cuts have healed and disappeared completely. Apart from the fact that hitting an existing bruise again can be very painful, it can also cause other - persisting - problems such as scars. Under the skin scars are one of the main dangers, especially when it comes to caning and intense flogging. The scar will not be visible, since it will be embedded in the natural fat (especially on the bottom and breasts) but unfortunately it will appear at a later age - or after reducing your body weight - as a very nasty "bump" that will not go away anymore. A bruise will tell you that that particular part of the body has had as much as it can handle and that any further activity may cause more permanent damage.


Permanently damaging nerve ends is another hazard. There are thousands and thousands of nerve ends in and directly under your skin and losing one or two won't create dramatic changes, especially not in your bottom. Losing one nerve end there will only cause the loss of sense in an area less than a square millimeter and the neighboring nerve ends are very likely to take over. However, in other areas, such as around joints, the anus and genital area, this is an entirely different story. Damaging nerve ends there may cause loss of sensitivity. For that reason, in my opinion, bruising areas like the labia/clit should be prevented as much as possible.


There are a number of other non-scene medical conditions that can cause bruising, too. The wise thing is to consult your doctor just to be sure nothing really important is overlooked because you thought it was from a scene, when it was maybe unrelated to your kinks, but serious anyway for other reasons.

A web based medical advice site is WEB MD. Check it when you want and need a medical question answered online.

Only a few slaves can I be hardcore with & leave sever marks, but every1 else has a family, so if your an artist, like me you can prevent marks from appearing for long periods of time.

I don't leave scars or marks.....I think that is a bit beyond my comfort zone....my clients have to return home to their families.........the point is to have fun and experience a fantasy for a few hours....it makes it more exciting that the only memories thay have when they leave are mental images....and perhaps a review.

See, that is one of the big differences between being a provider that Tops, and being a provider that Bottoms/is the submissive.

Most of my clients do not have the tools, time, any place they can practice learning how to crop, flog, let alone cane without leaving marks.  i have simply taken the wood (no pun intended) out of my sub bag.

Yes, it is possible to cane, crop, be paddled and have no marks that last.

i took a two hour caning a month ago in Manhattan, given by a pro Domme (my client hired and wanted to watch).  i still have the broken skin healing, it simply doesn't heal as fast as when i was 20 years younger.  i had a great time though and i was compensated to my satisfaction.

i did ice my affected areas immediately when we finished and the next day the only marks were the broken skin that wept for two days.  Most likely not the scene provider Tops give patron bottoms.

If you have any question in your mind as to whether something will leave a mark, ice it for 20 minutes.  

i can't begin to tell you how passive rope looks and how vicious it really is.  

i posted the information as a resource, just in case, even ONE person needed it.

~a