Crafty Cabbage

Black Mould Treatment of Silicone Sealants

January 17, 2025 by Crafty Cabbage

Getting rid of the black mould that always appears on silicone sealant is a perennial problem (Photo 1). I've seen lots of claims for homemade remedies, usually involving either bleach or vinegar on their own or mixed with baking soda (sodium bicarbonate). In my experience, these may work (partly) with relatively fresh mouldy stains but do not touch ingrained stains. I've always assumed this was because the black mould grows into the (water-repellant) silicone which is inaccessible to water-based remedies. I could be wrong on this and, certainly, you will find lots of testimonials on the efficacy of such products.

Photo 1: Ingrained Black Mould near the Kitchen Sink

As a first step, you might want to give the homemade recipes a try; especially if you already have the ingredients. Long contact times (4 - 24 hours) are recommended so don't be in a rush to wipe off your weapon of choice.

If your homemade recipe doesn't cut the mustard, what other options do you have? I would say you have two: either use a commercial cleaning product or remove the offending silicone and reapply fresh silicone. As a general rule, fresh silicone does not adhere to old silicone which is why you have to remove the old stuff first.

1. To remove the old sealant, you will need a silicon seal remover kit (Photo 2) available from all good hardware stores. The kit includes a brush with which to apply the silicone softening gel and a plastic scrapper to remove the treated silicone once it has softened (15 - 60 minutes later). It is worth removing any loose silicone before the first application and you may need to repeat the process.

Photo 2: One of Many Silicone Removal Kits

Once you're happy that you have removed as much as you can, use a wet cloth to clean the area of residual silicone softener and allow it to dry completely before re-applying a suitable anti-mould silicone product.

For small jobs, you can buy squeezable tubes of sealant but it is probably worth investing in a sealant gun and using the more cost-effective silicone cartridges. Be aware that even anti-mould silicone products will eventually need to be replaced - nothing is 100% mould-proof.

In the past, I have found this Unibond Special Sealant works well. It is less viscous than your standard silicone sealant and will adhere to old sealant. I still recommend you try to remove as much old sealant as possible though.

Photo 3: 'Special' Silicone Sealant

2. The second option is to use a commercial cleaning product of which there are many sold on Amazon.

Photo 4: Successful Mould Remover

While the various products appear to be similar (containing a bottle of anti-mould gel, a brush, a cloth and a disposable glove, Photo 5) ...

Photo 5: Box Contents

... the ingredients in the active gel do vary. For example, the active ingredient in the Aticers product (Photo 4 & Photo 5) is N-(hydroxymethyl)urea, a biocide. The Glowpoint mould remover gel (Photo 6), on the other hand, is a chlorine bleach (sodium hypochlorite) based product.

Photo 6: Chlorine Bleach Mould Remover

So far, I have only tested the Aticers product and I was moderately impressed with the ease of use and the efficacy of this product. Photo 1, at the top of the page, shows the pre-treatment condition of the silicone sealant. After one application (12 hours between gel application and removal, Photo 7) ...

Photo 7: After One Application

... and after a second application (12 hours between gel application and removal, Photo 8) ...

Photo 8: After Two Applications

The Aticers product did a reasonably good job despite the age of the mouldy sealant (8 years). Some mould stains reacted better than others to the treatment. When applied to a relatively new (1 year) sealant mould in a shower cubicle, the black mould was not visible after treatment.

I will report separately on the performance of the Glowpoint product.

The main advantage of the commercial cleaning product was that the shower/sink was not taken out of use for the cleaning process. After ensuring the sealant was dry by rubbing with an adsorbent paper towel, the gel was applied before going to bed and removed (wet cloth) first thing in the morning. Removing then replacing the silicone sealant (Option 1) not only takes longer and more effort, but the sink/shower/bath is out of action for a longer period (24 hours).

I have some tougher mould stains to try out these two products and will report at a later date. If the chlorine bleach product (Glowpoint) works well then I may need to rethink the homemade recipes!

2024 - Warmest Year Globally and Third Warmest for Herefordshire

January 14, 2025 by Crafty Cabbage

The reign of 2023 as the warmest year globally was as brief as it could be; 2024 has just superceded it. Not only that, according to the Copernicus Climate Change Service, we surpassed the preferred 1.5 ℃ limit, agreed at COP21, for the first time (Figure 1). Note that, according to the 2015/2016 Paris Agreement, we have not yet broken the 1.5 ℃ limit; to do this requires an extended period (5 - 10 years?) where annual global temperatures are consistently above the 1.5 ℃ limit. As we move into a La Nina phase of the El Nino/Southern Oscillation (ENSO), the average global temperature for 2025 is expected to fall back below 1.5 ℃. We may breakthrough the 1.5 ℃ limit anytime from 2030 onwards.

Figure 1: Annual Global Average Temperatures Compared to the Pre-Industrial (1850-1900) Average

Most disconcerting is the fact that the last two years have not only 'smashed' the mean global temperature records but, for 2024, achieved this even as we moved from an El Nino phase (warming) to a La Nina phase (cooling) (Figure 2).

Figure 2: Monthly Sea Surface Temperatures (Nino 3.4 Index Values) from NOAA

Of course, using a single number to summarise a global effect (warming, in this case) will necessarily lose information. Not everywhere will warm, some places will warm less than the average and some places will be much hotter than the average. I was interested to see how warm the last two years (2023-2024) were in Herefordshire.

I have done a couple of blogposts on Herefordshire's climate history; see here and here. As a proxy for Herefordshire, I use weather data from the Met Office's Ross-on-Wye weather station located in the south of the County. Monthly data on temperatures (maximum and minimum), rainfall, sunshine hours and the number of air frost days are available from 1931 onwards.

In Figure 3, the mean annual temperatures for the Ross-on-Wye weather station are as a time series. There is a good deal of scatter (as you would expect from a single weather station) but also a clear warming trend.

Figure 3: Average Yearly Temperatures for Ross-on-Wye (1931 - 2024)

The same data, this time as an anomaly plot using a 1931-1960 baseline, is reproduced in Figure 4.

Figure 4: Temperature Anomalies (1931-60 baseline) for Ross-on-Wye Weather Station

In the historical record (1931-2024), the three warmest years are 2022, 2023 and 2024 with 2023 being the warmest and 2024 the third warmest. The temperature anomalies for 2022, 2023 and 2024 are, respectively, 1.8 ℃, 1.9 ℃ and 1.7 ℃. To these values we could add 0.1 ℃ to move the temperature baseline back to the pre-industrial period (1850-1900). Unless 2025 is much cooler than 2024, it seems likely that, in terms of global warming, Ross-on-Wye (and, perhaps, Herefordshire) has already broken the 1.5 ℃ limit.

View from the Rear Window - April 2024

January 09, 2025 by Crafty Cabbage

April - originally the second month of the year (Aprilis) in the old Roman calendar (after March), its origins are a bit hazy. Possibly named after Aphrodite though the more widely accepted origin is from the Latin word aperire meaning 'to open' signifying the start of Spring when flower buds burst open.

A couple of photos from the daily garden pictures this month: the first (Photo 1) on the 6th with its fine display of tulips, and the second on the 26th (Photo 2) where the wisteria and acer take centre stage.

Photo 1: Rear Garden (6th April 2024)

Photo 2: Rear Garden (26th April 2024)

The daily garden photos are presented in Video 1:

Video 1: Daily Photos of the Rear Garden (April 2024)

The Met Office's summary for April 2024 was unsettled, wet and dull. While generally true for Hereford, the details are more nuanced. The table below summarises the weather statistics for a city-based garden in Hereford (i.e. my Davis Weather Station). Overall, not too bad and a reasonable one for gardening and vegetable sowing and planting where the absence of April frosts (unlike 2020 - 2023) helped greatly.

April 2024
Weather Parameter	Value	Dates
Average Monthly Temperature	10 oC
Maximum Monthly Temperature	21 oC	12th
Minimum Monthly Temperature	0 oC	18th & 20th
Number of Air Frost Days	0
Number of Hot Days (> 25 oC)	0
Monthly Precipitation	55.4 mm
Greatest 24 h Precipitation	10.2 mm	4th - 5th
Number of Dry Days	12
Monthly Sunshine Hours (estimated)	146
Highest Wind Speed	48 km/h	15th
Heating Degree Days	236.7
Cooling Degree Days	0.4

Daily maximum and minimum temperatures are plotted in Figure 1 (click on the figure to see a larger version). The month started reasonably warm but cooled off towards the end and meant I had to bring some of the vegetable plants in(doors) from the polytunnel because of the cooler nights.

Figure 1: Min/Max Daily Temperatures (April 2024)

In Figure 2, rainfall and solar radiation (proxy for sunshine hours) are plotted. Most of the rain fell during the first part of the month - a sort of extension to wet March. The final two thirds of the month were moderately sunny and dry though not especially warm (Figure 1).

Figure 2: Rainfall & Sunshine (April 2024)

How does April 2024 compare with the same month in 2020 to 2023? See Figure 3 and Figure 4.

Figure 3:

Figure 4:

Jobs in the Garden

Disinfect plant pots, seed trays, Quadgrow planters, etc with Citrox P
Pot up cucumbers, tomatoes, chilli peppers, courgettes & aubergines in 9 cm pots and harden off in the polytunnel (April 7th)
Sow celery and celeriac in seed trays (April 11th)
Sow French Beans (Cobra) in Root Trainers, a few at a time for succession sowing (April 11th)
Direct sow chard, parsnip & beetroot (April 11th)
Sow chard, perpetual spinach & beetroot into Salad/Veg Planter (April 12th)
Possible frost on the 18th; transfer polytunnel plants indoors and return to polytunnel on 28th.
Asparagus cropping; 20 spears
Sow parsnip in Salad/Veg Planter seed bed after potting on beetroot, chard and spinach (April 22nd)
General weeding and composting

Flora & Fauna (seen in the Garden)

Unidentified (moved too fast) 'white' butterfly (April 7th) & this one on the 12th

Photo 3: Small/Large White (male) on 12th April?

Red Admiral butterfly (April 9th)
Holly blue butterfly (April 11th)

Video 2: Recently Emerged Holly Blue Butterfly (11th April)

Bat seen in the evening (April 11th)
2 x Blackbirds (male & female)
2 x Blue Tits

Video 3: Blue Tit Singing (16th April)

2 x Collared Doves
1 x Crow
1 x Dunnock
2 x Great Tit (male & female)
7 x House Sparrows
2 x Herring Gulls

Photo 4: Herring Gulls

1 x Lesser Black-backed Gull
1 x Magpie
8 x Starlings
3 x Wood Pigeon
1 x Wren

And, finally, a few pics from the garden:

Photo 5: Snake's Head Fritillery (3rd April)

Photo 6: Our Small Garden Pond (3rd April)

Photo 7: Bluebells (3rd April)

Photo 8: Holly Berries on a Sunny Day (3rd April)

Photo 9: Tulips

Photo 10: Front Garden (3rd April)

Photo 11: Front Garden (3rd April)

Photo 12: The Art Shed

Photo 13: Aster (Leopard's Bane?) - 12th April

Photo 14: Saxifrage

Photo 15: Forget-me-nots

Photo 16: The Paradise Garden (23rd April)

Photo 17: Wisteria (30th April)

Photo 18: Acer

Photo 19: The Secret Garden

View from the Rear Window - March 2024

January 07, 2025 by Crafty Cabbage

March - derived from Martius (named after Mars, the Roman God of War) and was the first month of the earliest Roman calendar.

I have been somewhat lax in doing my monthly updates. My only new year resolution is to try and catch up. This is largely for my benefit so I can maintain a long term phenological record. The monthly reports may be somewhat briefer than usual.

The month was dull and wet with middling temperatures. It was nice to see the cherry blossom though (Photo 1).

Photo 1: March 20th 2024

The usual video showing the daily photos of the rear garden ...

Video 1: Daily Garden Photos (March 2024)

Weather data recorded by my garden Davis Weather Station are summarised in the table below:

March 2024
Weather Parameter	Value	Dates
Average Monthly Temperature	8 oC
Maximum Monthly Temperature	18 oC	9th
Minimum Monthly Temperature	-2 oC	3rd & 4th
Number of Air Frost Days	4
Number of Hot Days (> 25 oC)	0
Monthly Precipitation	99.2 mm
Greatest 24 h Precipitation	23.0 mm	27th - 28th
Number of Dry Days	12
Monthly Sunshine Hours (estimated)	102
Highest Wind Speed	39 km/h	23rd
Heating Degree Days	311.5
Cooling Degree Days	0.0

Daily minimum/maximum temperatures are reproduced in Figure 1. Daytime temperatures held up well but the nights were cold overnight for the first 7 days of the month.

Figure 1: Minimum & Maximum Daily Temperatures (March 2024)

Significant rain at the start, middle and end of the month (Figure 2):

Figure 2: Daily Rainfall & Sunshine (March 2024)

I now have 5 years of weather data from my Davis Weather Station and it is possible to discern some trends in the weather. Of course, it will need much longer records (10-20 years) to positively identify climate changes. While the mean daily temperatures have been constant over the last 5 years (Figure 3), this may be hiding a trend towards lower daytime maxima and higher night-time minima.

Figure 3: Temperature Data for March (2020 to 2024)

The trends in rainfall and sunshine seem clearer though the timescale is too short to be certain (Figure 4). In this location, the month of March is getting wetter and duller (less sunshine).

Figure 4: Rain, Wind & Sun Trends (March 2020 - 2024)

The three figures below are taken from the Met Office's Monthly Report for March 2024. Herefordshire, where we live, is marked on the maps. March 2024 was just a little bit warmer in Herefordshire than the 1991-2020 average (Figure 5) but, as Figure 3 showed, this March's mean monthly temperature was not especially warm for Hereford and was, in fact, typical of the current decade (2020s).

Figure 5: UK Mean Monthly Temperature for March 2024

The UK map (Figure 6) for rainfall shows significantly higher than normal precipitation for parts of England, including Herefordshire. Thus confirming the local data recorded by the Davis Weather Station (Figure 4).

Figure 6: UK Monthly Rainfall (March 2024)

With much higher rainfall comes lower sunshine hours (Figure 4 & Figure 7).

Figure 7: UK Monthly Sunshine Hours (March 2024)

Jobs in the Garden

Hand weed and shallow dig (six inches) the potato and onion beds incorporating sieved home-made compost/soil improver
On March 9th, plant out red & white onion sets plus garlic started off in the greenhouse
On March 14th, plant out the chitted seed potatoes (Foremost & Nadine)
Start off tomatoes, sweet peppers, aubergines, chillies and cucumbers ready for planting out in the polytunnel in April/May. Cucumbers germinated.
Plum and pear trees start to flower. The plum flowers were the first ones for these trees planted about 5 years ago. Unfortunately, the fruits did not set.