Dyed circulars and cardboard, for weed barriers under mulch

Question

[Box bottom listing dyes]

I have always saved and used layered newspapers (without the dyed circulars) as a weed barrier, under the mulch in my gardens. When I am done, the papers are not visible.

Now, I'm tackling a large area and ran out of the regular newsprint (even with friends/neighbors saving it for me). I'm considering using the sales circulars, magazines and dyed cardboard as weed barriers. We aren't growing edibles in this specific area, but it does flood. I've tried to research this, but all of the sites seem to strongly disagree about the pros and cons.

(i.e. Pro- They hold up longer than the regular newsprint, which can be helpful in some cases. Con- The dyes leach into the soil.)

So...Should I go ahead and use them in my own yard, or should I just put them in the recycling bin to go to the landfill and leach their dyes into the soil there? Everyone seems to be up in arms about these dyes! How bad can these dyes really be?

Answer 1

Brochures and coloured flyers do not have to disclose what inks are used to print them so there is no hard and fast answer to your question. Different printers could use different inks.

Printing inks can be divided into a few different types which are detailed here.

• lithographic
• heat set lithographic
• coldset lithographic
• flexographic
• water or solvent based gravure inks
• UV inks

Here is a material safety data sheet for a black printers ink. There are some alcohols,resins and carbon black none of which seems very toxic.

A more detailed list of Material Safety Data Sheets is found here. A cursory review shows the components mentioned above and manganese and cobalt which are found in the soil. I found this MSDS which states "In compliance with local, state and federal regulations. The product should not be allowed to enter sewers or water streams."

The absorption of anything into the soil or plants depends on unique soil chemistry, time of year, type of plants and other factors so it is very difficult to say if there is a health risk. Probably not to you, perhaps to anything downstream.

A worst case assumption is that when you put anything in contact with the soil it starts to degrade. Over a variable period of time, depending on many things such as rainfall, soil type and so on everything in the flyer will be in the soil.

Given that bags of mulch are commonly available for a few dollars a bag I would rather use them than an unknown quantity. It is very difficult to tell what inks are used on flyers and what their effect will be on the environment.