Black Marks & Mildew On Door Seals
The causes of mildew and marks on door gaskets and how to solve it
This, as shown in an extreme example in the photograph to the right, is caused by a bacteriological build-up in your machine due to poor cleaning. It really is that simple and, all too often, it is caused by incorrect detergent use.
What happens is that under-dosing or using the incorrect detergent for too long without performing a maintenance wash will allow bacteria to build up in the washing machine, which will grow very happily in the warm damp conditions, which will eventually lead to what is shown here on the door seal or door rubber as some people call it.

Also, using solely liquid detergents, liquid tablets, colour only powders (or liquid) as well as most of the “alternative” products like Soapnuts, Ecoballs and Ecover do NOT contain any bleach and will not remove any bacteria effectively. Should you wish to use these alternative products, you will also have to add bleach to prevent “greying” of your whites over time as well as other problems.
You can read much more about these natural products in this article
Leaving the machine door slightly ajar when not in use also massively helps as this allows the seal to dry out and hinders the growth of bacteria inside the washing machine’s drum as well as the door seal.
Effects On Your Machine And The Cure
As you can see from the photograph, the effects are extremely visible and noticeable to the naked eye and whilst a maintenance wash will help the situation, depending on how bad it is, there may well be no alternative but to replace the door seal. On most washing machines, you can expect to pay about £60-80 to have this done by an engineer using the engineer search if it really is bad.
Ultimately the only real cure is a replacement door seal on the washing machine and regular maintenance washes thereafter.
But before you call an engineer in try cleaning the seal with a little bleach solution and a cloth; it may clear it if it’s not too bad.
There have been some reports of other cleaning products working in some instances, but these are sketchy at best for the most part, and it is very hard to get into the crevices of the door seal to get it clean.
In cases where this does happen, I’m afraid that almost every time, it’s too late by the time that you do something about it, and there is little alternative bar a replacement door seal and that prevention is better that the cure. Of course, you can find a replacement door seal for your washing machine in our washing machine spares section.
To keep your door seal clean, we can recommend the use of Affresh. We’re not saying that it will cure every single case because, as we said, if it is really bad already, the only solution is to replace the door seal, but as a preventative cure and the general health of your washing machine, it is very good.
More On Washing Machine Cleaning
You can find more, as well as related, information on the effects of not carrying out a maintenance wash from the following articles:
Smelly Washing Machines how to avoid nasty smells and get rid of them
Washing Machine Health Risks all about biofims, dark spots, mildew, mould and more
Washing Machine Soap Drawers how to clean them to avoid smells and bacteria build-ups
Maintenance Wash What it is and why it is important
Whiter Whites, Brighter Colours how to use detergents correctly.

Hope this is the correct box. I have a Bosh avantixx dish washer…..I have checked my machine but can not find any where the model no and batch no…..any help would be much appreciated.John M. Fox
This is a fabulous site. Thank you for taking the trouble to put this information on here. Single Mum and just fixed my machine. Thanks :).
My washing machine has started to get a burning smoky kind of smell when I use it. The plug doesn’t feel hot so I’m thinking could it be the heating element and is it safe to carry on using it. Everything else works fine.
my hotpoint washing machine door will not open have tried several cycles but no joy
I have small black marks on my white washing when I -do a hot white wash is this a bacteria can you tell me what to buy to cure the problem
Yes it is probably gunk inside the machine that has built up over time.You can try running a maintenance wash or use Affresh to try to clear it. How long that will take is hard to say as it depends on how gubked up the machine is inside.
Sludge on clothes. Have tried Clr, vinegar and even dishwasher cleaner. Still keeps coming back. Cleaned soap dispenser etc. any suggestions.
Washing keeps coming out on 40degree wash with large grey oil looking marks cleaned washer, boil washed and done again but still doing , does any one know what this could be pls
Washing machine making grey oil like large marks on clothes, cleaned and boil washed but still doing it, only on 40degree or less wash?
We have a Panasonic Cold Fill Washing Machine. Door seal and Glass get dirty we have used the Maintenence wash. I think the Heater is not working. How can I check.
Hi Brendan
If the machine goes through the cycle then it is extremely unlikely that there is a fault with the heater.
This will not appear as a link but if you copy and paste it into your browser you will get an explanation of that:
http://www.ukwhitegoods.co.uk/help/fix-it-yourself/washing-machine-washer-dryer/4062-washing-machine-heating