Thread: Rusting Paint tins

Hi Bob,

Good question. I have found the same thing, the bottoms all rust out.

Agreed to store a mate's garden shed contents while he did a renovation, included lots of paint tins, 4 years later they were still in my shed, went to pick them up and ended up with paint all over the shed floor. The bottoms had rusted out. Not happy Jan.

Cheers
Pops

Hi Bob,
After many painting jobs I have come to the conclusion the keeping a tin with a few centimetres of paint in is a bad idea. Firstly, the tins do rust and contaminate the paint (before they leak all over the floor), and you can't use the paint to do a touch up because the wall/ceiling paint has faded or become dirty and the touch up stands out like dog's bollocks. Also, I have noticed that some water based paints go bad after a few years and really stink.

I have tried keeping paint in a plastic drum )2 or 3 litres) with a good lid. They don't rust but some of them do smell.

I am now moving to buying the right amount of paint and tossing what is left over, then buy new paint in 5, 10 or 20 years - whenever the repainting bug appears.

I guess when you say 'rusting through' , you mean from the inside out.

I've seen paint tins rust from the ouside in, particularly if they're left sitting on a cold hard surface e.g. concrete, with no air gap under them. You get condenastion on the underside of the tin and bingo, rust.

Paint just does not keep.
Water based paints rust the tin or go off. Oil based skin and dry out. As beer is good suggest, it is not worth keeping a little bit of paint. I have even tossed a new tin of paint that I kept a couple of years because of rust.
When I ask clients if they have paint to touch up an area I am shown a collection of tins that have often been kept outside - I will not use them except to get the colour name or formula to try and match.

Originally Posted by beer is good

Hi Bob,
After many painting jobs I have come to the conclusion the keeping a tin with a few centimetres of paint in is a bad idea. Firstly, the tins do rust and contaminate the paint (before they leak all over the floor), and you can't use the paint to do a touch up because the wall/ceiling paint has faded or become dirty and the touch up stands out like dog's bollocks.

I'm talking tins that are still 3/4 full. I know what you mean about the rust affecting the paint. We have a built in cupboard where the frame and architraves were painted one year and then with the same can of paint a year later but unbeknownst to us a some rust flakes fell into the paint from the lid but I kept on painting assuming the slight colour difference was due to the paint being wet - but it wasn't and now it stands out.

Can only suggest it's because of the water base nature of new paints. Have thrown out my fair share as well.

I have had to happen to me some 10 - 15 years ago and in light of this I keep the paint tins in plastic shppoing bags.

Getting a little side tracked here I have been told that once you open the tin the paint it starts to go off as the seal of the can is not longer tight as it was originally. It was suggested after closing the can to turn this upside down. This prevents air from getting inside the can.

I have done this from two perspectives with my finishes and some paint cans also in the plastic bags.

Rusting of paint tins has been a problem for paint manufacturers ever since water based emulsion paints were introduced.

When emulsion paint is manufactured the pH of the paint is adjusted to a range 7.5 to 9.5, as the emulsion is not stable below 7.0. This adjustment is generally done with ammonia, some manufacturers use amines, which are less volatile.

Over time on storage the ammonia evaporates and the pH lowers to the acidic side on storage, especially in part filled tins.

There 2 ways to combat this, first store the paint in plastic containers, but this adds to the cost of the paint. Second coat the inside of the tin with an epoxy based varnish, this works but only for a limited time as the joins between sides bottom are particularly prone to attack.

If you have left over paint that you want use at a leter stage for touch up etc, the best way is to decant it in to plastic container that seals properly and have as little air space as possible.

Paint manufacturers also add fungicides to the emulsion paint in an effort to overcome fungal attack, waterbased paints are an ideal environment for this fungal attack. Again, over time these become less effective, particularly in warm/hot storage areas.

If you store your paint tins on timber slats they generally will not rust away. Make sure the lid is fitted into a clean groove then seal around the tin with duct tape to make it air tight. I have tins which have lasted and in good condition including the paint after ten years using this method.


Regards Mike

I can understand the frustrations as I have over the years had similar experiences, especially if you are doing the painting over a period of time and not using it all at once.

However, my biggest gripe over the whole paint problem is the restricted tin sizes - you either buy large and save on the per litre cost but have larger than necessary leftovers, or you buy small and the excessive costs associated with buying enough paint to do a job with the minimum of leftovers nearly force you to sell a kidney to buy the paint. I understand that buying 4 X 1 litre tins should be more expensive than buying 1 X 4 litre tin but do not accept that the differences are or need to be as huge as they are in reality.

Thanks for the tip about the wooden slats and plastic tubs

I once tried turning the paint tin upside down - the lid rusted.

I have had this happen to two tins this year, but just pin holes and no real rust on the outside.

One was a tin of bondcrete and I can't remember the other ( both 4L about half full). I turned them upside down and sealed the holes with silastic.

Regards
Paul