Capillary Matting

Hi All :gnthb:

I recently moved into a house that has a good sized greenhouse (8ft x 12ft) to boot and built myself some staging. Today I have put plastic on the top, capillary matting and this perforated plastic that keeps down problems with algae.

My Q is this...

Do I need to prime the matting with a good soaking for it to start working? I put the end of the matting in a tray of water so it could "wick up" but it didn't do anything and the mat is still totally dry

Cheers

Paul

 

Hi Paul
It should wick by itself from dry, you do have to be careful of the height between the water and the mat though as there`s a limit to how high it can lift the water.

 

IME you need a good quality capillary matting (basically "thick") for it to work well. When I used it only the commercial grade seemed to be any good, the stuff I bought at the garden centre didn't have the same "pull"

 

Hi Paul

It depends on what material the matting is made from. Dry cotton under normal conditions is made up of about 40% water. So it wets and wicks very easily and makes a superb matting. This is why all towels are made of cotton. But cotton is a natural fibre and will rot after a while when wet - so is rarely used. The same goes for wool.

Your product is likely to be 100% nylon. But dry nylon is made up of only 4% water. Its strength is that it won't rot, but that low water content means that it doesn't wet or wick very easily. So the answer is that you will have to prewet it first. It will draw water up a short distance from a tray of water, but its not very good at it, so keep the height as low as possible.

You can test the material by putting a match under one end. Nylon will melt and drip, cotton won't. As Kristen says the thicker the material the better, but however thick it is, you can't get away from the fact that it is nylon. Polyester holds even less water at 0.4% - which makes it quite unsuitable.

 

The stuff i have is about 3-4mm thick when dry and has 7 layers, the top one is black and the rest are white. According to the spec it`ll hold 3.5L/m2.
You can use hessian cloth as a biodegradable capillary mat. Using a slow drip feed from a container above, it`ll wick sideways but not upwards :wink:
I figured out what brand i have, its called Aquamat, it has 14 layers not 7 as i thought.
Field Capacity - 3.6 litres per sq.m
Capillary Rise - 7cm or more depending on water softness

 

When I was a teenager I used capillary matting in my greenhouse because I was mad keen on pot plants - Fuchsias, Freesias, Achimenes, Cyclamen ...

Anyways, I attached some plastic downpipe, horizontally, to the staging with a bend, pointing upwards, at each end. I cut slots along the side of the pipe, i.e. what was then the "top", about 4" long and 1/2" wide, and then a 2" gap with no slot. I used scissors to cut the edge of the cappillary mat so that there were wicks that came over the edge of the staging into the slots in the downpipe, and then filled up the pipe with water.

The greenhouse was 10' long, the staging about 3' wide, I am guessing that downpipe is 4" diameter, and if my calculations are correct that's about 25 litres capacity, so 2.5 L per foot run, or 0.8L per sq. foot. I have no idea how much is required for the day? I watered the surface of the cappilary matting with a rose, and filled up the downpipe "tank" each morning, and I suppose again during the day if it ran out.

It worked well, any only had 3' width to "pull" the water, rather than a tank at the end of the staging which would have to "pull" much further.

25 litres of water is 25 Kg, so do consider the effect of the weight on the staging!

 

I like your downpipe water reservoir idea, makes for an easier life for watering. Hand watering loads of seperate pots can take a fair while, especially if some dry out faster than others.
Capillary mat is useful stuff.

 

One point about using capilliary matting. Its easy to get the matting wet and to put pots on it. But you have to be sure that the soil in the pot is in contact with the wet matting. You either need flat bottomed pots, or a thick matting so that the pot can sink into it - preferably both. If you are not sure, say with bigger pots, you can shove a small wick into the hole in the bottom of the pot, so that the top of the wick is in the pot and the bottom of the wick is in contact with the matting. A wick could just be a short strip of the material.

As Hex said, the capilliary rise measurement tells you how good the product is at wicking and moving water. Nylon matting may only lift water 2 or 3 centimenters. The Aquamat says 7 cms, but cotton is more like 50 to 70 cms. There is nothing to say that you can't have a cotton (old towel) wick to lift the water up from a bowl, with the top end tucked under the capilliary matting which will then distribute it sideways.