How to treat red rot and other bad problems
- Peter Smith
- Feb 24, 2023
- 8 min read
Updated: Sep 24
In this article we look at various problems that have affected aged leather articles.
There are a lot of things that can effect the health of leather articles. From dry rot (red rot) to cracking, scuffs, scratches to tears and cuts.
In this article we take a look at the following (more common issues).
Red rot
I have worked on several articles with red rot, such as this project here.
What is Red Rot?
Red rot is when leather has dried out and deteriorated over time and appears as a red "dust" on the surface of the leather. Although you may see this on the surface of the leather, the deterioration goes deep into the fibrous structure. At this stage, the leather will tear easily or even just fall apart as there is no structure and strength left.
If left untreated, the leather will disintegrate completely, get weaker and tear easily and stitches won't hold.
Cause
The causes of red rot are not fully understood but it is said that various acids, including those used in the tanning process and exposure to pollution among other examples, cause the breakdown of the fibre in the leather.
Liquids and heat can accelerate the process of drying, which can lead to red rot.
Prognosis
If left untreated and not suitably stored, the leather will continue to disintegrate.
Treatment
There is no treatment that can reverse the effects of red rot. So we are into conservation and preservation mode.
To arrest red rot, sealants and consolidators, formulated especially for this are used.
Some Museums may treat red rot with a specially formulated leather consolidator.
The museum preference however, for older and delicate articles is not to do any treatments and will prefer placing articles in controlled storage such as archive boxes, cabinets or display cases where temperature and humidity is controlled and acid free tissue paper or other barriers are used to protect the article.
The decision to treat or to just store is up to the article owner and comes down to the severity of the damage and what the owner would like to do with the article.
Drying and cracking
There are many articles I have treated in this state such as this holdall.
Old articles, especially those with a thicker, vegetable tanned leather, which have not been treated and stored correctly, will go dry, brittle and crack, I have seen this in countless articles such as cases, hat boxes, and more.
Symptoms
Dry leather feels and looks dry and will tear easily. You may find that even the thread in the stitching has rotted and breaks easily. The surface of the leather may have cracks and parts of it may be peeling off.
Cause
Drying out of the leather due to age, heat, the weather and lack of treatment.
Prognosis
If left untreated the leather will continue to dry out and deteriorate. It will become more and more brittle and fragile. It will become so fragile that it will tear very easily. The surface of the leather will start to chip away. Red rot may set it.
Treatment
When leather is in this state, we are again, into arresting and conservation mode.
There are several processes I use to arrest further cracking and flaking. I use a combination of a leather binder, a consolidation product and then finishing with a seal.
All the products used are specially formulated to treat, feed and preserve the leather to extend it's life.
To re-iterate however, we cannot reverse the effects of dry leather.
Stains and spills
Think of leather as blotting paper! Leather soaks up liquid deep into the fibres and even water will leave a stain mark.
Stains are difficult to remove if they are oil based or caused by ink spillage. Water and other liquids such as perfume are relatively easy to deal with if the article can be soaked in water!
Symptoms
You will see darker patches or even coloured patches if colour has transferred onto the leather or the stain is caused by ink or other coloured liquid.
Cause
Spillages, rain, water, oil, perfume, etc.
Prognosis
In some cases, the stains are not damaging to leather. Other stains can be permanent, such as ink or dye transfer. Others, like water stains can be treated, depending on the article.
Treatment
This depends on the type of leather and nature of the stain. Ink or dye stains are permanent!
Suede is particularly difficult to deal with. Some, and I mean very few, suede items can be washed - not something I will do since this will shrink and dry the leather out and make it stiff.
For water stains, such as in the photo above, the process is to wet the whole article, then let it dry naturally (no heaters or hair dryers!). After this, treat the leather with an appropriate dye, such as an oil dye, or my favourite, an antique gel. Don't use water or solvent based dyes unless you really want to change the colour.
NOTE: you can only change the colour if you are going from light to dark...
Tears and cuts
Unsightly and damaging tears are common especially in older articles.
Symptoms
Tears and cuts. Dry or weak leather may even split under stress, like the photo below.
Treatment
I am often asked if I can repair tears and cuts.
Yes I can - if the leather is in good condition and if the tear is not too long. There is no point in repairing leather that is already frail and tears easily.
Again, depending on the type of leather and what finish it has, a tear can be invisibly repaired. This is a process that can be done at home, if the instructions are followed carefully. Have a look at this article, which guides you through the process, along with what products to use.
Cause
Improper use of the item, stresses placed on the leather, e.g. seats, bag handles, heavy loads in bags, etc.
Prognosis
If left alone, the tear or cut will expand.
If the leather is dry, then replacing it will be the better option.
Scuffs and scratches
I do a lot of work on articles that have felt the wear and tear of life and every day use like this extreme example.
Symptoms
Lighter areas and patches from scuffs, rubbing off, etc.
Cause
General usage, wear and tear.
Treatment
There are different treatments for different types of leather and how the original leather was finished.
For non-porous leather, such as we get on leather furniture, you will be looking at a re-spray using a specially formulated paint. First the leather is cleaned, then the existing spray is removed with an alcohol. A cross-linker (curing agent for polyurethane coatings with improved durability, especially suited for use with automotive and furniture leather) is used with the paint.
For porous leather, you have a wider choice for restoring colour to your article. You can use a leather balm, which has been coloured or you can use an oil dye or antique gel. Your choice is driven by the final look you wish to have on the article.
Once you have dyed your article, be sure to seal it off so that the colour lasts and to protect the article.
Prognosis
Deep scratches can't be removed but the look of the scratches can be minimised and blended so as not to look so severe.
For fading and scuffs, most articles can be recoloured. My method for recolouring is such that all wounds will be blended so that scratches, scuffs and fading don't look so bad.
Faded leather
This is when the original colour has faded, leaving you with patchy colouration.
Symptoms
Lighter areas where dye has faded, possible hardening of the leather.
Cause
Direct sunlight, ageing.
Treatment
As with all leather articles, there are different treatments for different types of leather and how the original leather was finished.
The treatments are the same as for Scuffs and scratches above.
Prognosis
If left alone, especially if the article is in direct sunlight, the leather will fade further and will dry out, leading do dry rot issues.
Complex issues
Complex, or multiple issues are common with older articles, having any combination of the above.
When there are complex issues, the secret to renovation is 'the plan'.
First, make a list of all the issues you see. Look for all the issues you have read about in this article with some additional items you may want to address such as "polishing the hardware".
Make sure you are confident to deal with each issue.
Write down how you will deal with each issue. In some cases, you may have to dismantle the article in order to deal with certain issues. In some cases, I have completely dismantled articles down to their individual components (one article was made up of 46 pieces of leather!).
Write down what materials you will need for each issue.
Write down any outsourcing you may require. For example, you may need the services of some who can do gold foil embossing.
So, your plan is there. Now, gather your materials and if needed, research your outsourced work.
Before getting stuck in, write down the order in which you will execute the renovation and repairs listed in point 1 and 3.
Now, be brave, be patient! and get started. Don't be tempted by enthusiasm and skip your steps!
Tips for leather care
Leather is a natural product that needs to be maintained and fed. There are products that are designed for purpose. There are different products and methods for caring depending on the type of leather.
First identify what leather you are caring for before going ahead and applying any treatments!
Do not use any product with oil content. Be it mink, coconut, neatsfoot or others. Oil oxidises over time and will deteriorate your leather. Paradoxically, oils will dry out the leather and it will crack over time.
Do be careful about what you find on the Internet. Not all sites do know what they are talking about and are just out there to sell their products (which may not work and in some cases can make things worse!).
Do not use furniture polish and spray polishes. These contain propellants and ingredients that can cause more damage.
Store your items in a cool dry place.
Use the correct processes and products for cleaning.
If the leather is in good condition, keep it so:
For vegetable tanned articles
use a wax based, clear boot polish. Coloured polishes contain pigments and powders that you do not want on your leather item.
Polish the wax on, allow to dry, then buff off with a soft, lint free cloth.
For furniture or motor vehicle leather
Clean the leather first. I use Leather Ultra Clean from Furniture Clinic.
Then seal the leather with a protection cream, also available from Furniture Clinic.
Handle your article with care, trying not to get it scratched or scuffed.
Conclusion
Renovating, repairing, conservation, preservation! These are choices you should make before tackling your article.
Most of my work is about 'sympathetic repairs and restore'. Most of these articles can be used for their intended purpose.
Some of my work is preservation and conservation. The articles are too fragile to be used, so proper conservation is required.
What is done should be reversible (example: desktop inlays).
Do not use oils to treat leather. Seek out the best way to treat the type of leather you are working on.
The leather world can be very confusing when you are starting out. Different types of leather and different tanning and finishing processes make it hard to know what to do with your leather article.
When you are in need of some advice or help, I am here. Don't be shy, contact me and let's see what we can do.
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