Painting Cast iron furniture to make it last for years
At the end of the summer and before the dark nights of winter close in, I started to clear away my patio furniture, but before I can store it away this year I need to refresh the paint, as it was starting to look tired and dull.
Being Cast iron my garden furniture needs to be painted properly otherwise it could quickly start to corrode or rust, which means it looks ugly and would need to be replaced very soon.
So here’s how I went about giving it a new lease of life and treated it to a fresh coat of paint
To paint cast iron furniture clean it with a pressure washer or hosepipe, remove flakey paint and rust with a wire brush, rub the surface down with emery cloth, remove dust with a damp cloth and paint with red oxide primer, apply undercoat, and at least 2 top coats of metal paint, rubbing down between each.
This is one of the jobs that need doing every now and then and doing it properly will mean you will be able to enjoy your furniture for longer, check out the details for all tips and tricks.
Clean off any dirt
Find a suitable area to work on the cast iron garden furniture, firstly to clean the furniture off, this might be at the end of the garden or in a workshop, somewhere that won’t be a concern if it gets dirty, or can easily be cleaned up afterward.
For really dirty furniture I favor using a pressure washer to remove the loose dirt, algae, and any moss that can collect over the winter. If you don’t have a pressure washer you can use a hosepipe and a brush.
I recommend that you consider investing in a good pressure washer as they are useful for cleaning all sorts of things and make large outdoor cleaning jobs much quicker than doing it by hand. Have a look at our ‘Recommended Tools’ Page for our top picks.
Washing the cast iron furniture with soapy water and a stiff brush will get rid of any stubborn dirt or hard to remove algae or lichen that may have grown in the corners, for intricate detail that you can often find on ornate pieces of cast iron garden furniture, use an old toothbrush to clean off the stubborn dirt and grime.
Allow the metalwork to dry off fully and use a cotton cloth or a chamois to remove any excess water, make sure to get into tight corners where water may collect. Leaving the furniture to stand out in the sunshine for a few hours to help to dry off excess water.
On cold days take the cast iron furniture inside to a workshop and use a hot air drier to remove moisture from tight corners.
Remove old loose or flakey paint and rust
As with most DIY jobs, preparation is critical to getting a good finish, and putting in some effort at this stage will be well worth it in the long run.
Before applying fresh new paint to cast iron metalwork it is best to remove any old flakey paint or loose rust and treat the surface to prevent it from coming back
I always put down an old blanket or dust sheet before I start scraping the loose paint as this makes clearing up much quicker and stops paint from marking or sticking to the floor.
Use a combination of a wire brush and scraper to remove any loose or flaking paint and lose rust,
Make sure you use protective safety gear when doing this, I always wear a pair of goggles or safety glasses, a dust mask, and gloves.
With the surface of the cast iron garden furniture free of loose paint and rust, the surface needs to be rubbed down with a medium grit emery cloth or sandpaper, to remove any remaining surface rust and get back to bare metal.
I often use a cordless drill with an emery mop or wire brush fitted to speed up the process, and to get into tight areas or for really fine detail using a small drill or Dremel power tool with a shaped grinding head can work well.
With all the rust removed from the surface of the cast iron, Clean off any dust and lose particles with a brush and vacuum cleaner, and then use a damp cloth to wipe over the surface and remove the last traces of dust.
Apply Rust preventive primer
Like any metalwork that is to be used outside, treating the bare metal surface with a rust preventative primer will help keep your garden furniture in good condition for years to come.
I often use red oxide primer as this will give a good solid base for the paint to bond to and will help prevent rust from coming back, or you can use a good quality rust preventative formula, just make sure that anything you use is suitable for cast iron and can be painted afterward.
If you have a very ornate piece of cast iron then you may consider using a spray gun to apply the paint as this will make covering the more intricate details easier.
However, setting up a spray gun and an area to use it can often take longer than actually painting. If there are several pieces of furniture to paint for example if you have a complete cast iron patio set to repaint it could be quicker to use a spray system than painting with a brush.
Rub down the paint between coats
Once the cast iron is evenly covered with protective primer and the primer coat is dry, check the surface over for drips or runs or areas where the paint is too thick.
Paint can collect in tight corners or around ornate details,
You can remove the drips or paint runs by lightly rubbing them over with some emery paper, be careful not to rub the surface too much as this will remove all the paint and expose the bare metal underneath.
With drips and paint runs blended in gently rub-down the remaining surfaces to remove any specs of dirt or dust that may have become stuck whilst the paint dried on the cast iron.
Use a high grit emery paper or cloth to rub-down the surface, the aim is to create an even and smooth surface that has enough texture to allow the next coat of paint to bond to.
After rubbing down the surfaces, use a vacuum cleaner with a brush attachment to remove any loose dust or dirt, and then wipe over the surface of the cast iron with a damp cloth to get rid of any stubborn bits of dust.
Apply an undercoat of paint
Red oxide primer or rust preventive paints used to protect the bare metal surface of the cast iron furniture, have a dense color and will need an undercoat to help cover the surface ready for the topcoat.
The undercoat also acts as another layer of protection to help prevent the rain and weather from attacking the surface of the metal.
The undercoat is applied in the same way as the primer and can be put on with a brush or spray system.
If you use a brush make sure that details or tight corners are properly covered, sometimes using a small brush really helps. I tend to keep a set of artist brushes in my toolbox, as they are really useful for small details like the ones often found on cast iron furniture.
Rub down the undercoat layer
The next steps follow the same process as for the primer, the undercoat needs to be allowed to dry fully and then rubbed down gently with emery cloth.
Take care to treat sharper edges or corners gently as the paint tends to be thinner on these areas and rubbing too hard or too long could expose the bare metal surface, which will need to be repainted.
Then again use a vacuum cleaner to remove the loose dust and wipe the surface over with a damp cloth to get rid of the fine dust.
Apply the top coat of paint.
With the base coats of paint applied to the surface of the cast iron furniture, the metal should be well protected from corrosion and ready to have the topcoats applied
There are many different finishes and colors to choose from for metal furniture, and you can select a traditional black or white which gives the furniture a classic look.
A smooth gloss or hammer finish can give your ironwork a great look and feel.
Alternatively choosing another color can give your cast iron furniture a more modern feel, there are several shades of grey and green for example that can offer a contemporary twist to your furniture.
The choices are endless and you can mix them up and use multiple colors to give a bright or extravagant look.
Whichever option you go for applying the topcoats of paint on the surface of the furniture needs to be done with care, ideally using at least 2 coats to cover the surface and give good even color.
If the undercoat can be seen after a topcoat is dry 3 or even 4 coats may be needed to get the finish you require this is more common on lighter shades where the darker undercoat will show through.
Apply the topcoats using the same method for the previous paints making sure all the surfaces are evenly coated and any drips or runs are ribbed down between coats.
The final coat of paint
The last and final coat of paint should be applied once you are happy that the surface is good and the color has covered any underlying coats of paint.
Once again gently rub down the surface with a high grit emery paper, if you are looking for a high gloss surface then using 400+ grit will work well, any more than this becomes a polishing job.
Once the surface has been rubbed down for the final time. Give the surface a good clean down with vacuum cleaner and then a damp cloth to remove the last traces of dust,
The final topcoat will be the one you see for quite a while so take your time and make sure the surface is evenly coated, and there are no thicker areas, this helps to avoid drips or runs in the paint, as this time you won’t be able to rub them down.
Leave this to dry off fully, paint will normally be touch dry within a few hours, however, metal paint can require a couple of days before they have fully hardened and are fully cured, so take care when you are handling the furniture and don’t leave it outside until the surface is completely dry.
Always check the paint manufacturer’s instructions to check when the paint will be tough enough to withstand any rain or colder weather before you leave your newly painted cast iron furniture outside.
Painting cast-iron railings, fences, and other applications
This process for repainting cast iron garden furniture can be used on other cast iron or metal items that usually stay outside. Smaller items like doorknobs or knockers can be removed from the door to be painted in a workshop.
This makes working on them much easier as you are not at the mercy of the weather conditions and the task of repainting can be done at any time.
Lager items such as cast iron or metal railings can be painted in place, make sure that you check the weather forecast before starting a job like this, and plan ahead.
Depending on the size of the project you may need a couple of dry days to clean and paint the cast iron railings, and ensure that the temperature is above 41 Degrees Fahrenheit (5 degrees C) to allow the paint to dry off properly.
Any lower than this temperature and the paint will take much longer to dry and may not harden off fully, leaving the metalwork unprotected and likely to corrode or rust quickly.
I tend to favor carrying out these outdoor DIY painting projects in late summer or early fall whilst the days are still warm and dry.
At this time of year, the days are warm, but not too hot that the job becomes difficult. If the temperatures are too high then the paint will dry off so quickly you cannot cover the surface properly and leaves a poor finish which will need to be done again in no time at all.
Follow the process and tips in our painting guide above and your cast iron furniture and exterior metalwork will look great and be rust and corrosion free for many, many years.
If you liked this post, check out some more great information on preparing and painting exterior wood by following the link here.
This article was written by: Richard Quinton – The DIY Help Desk Owner, Engineer & technical specialist.
Richard is one of the key partners in The DIY Help Desk team. He is a qualified Engineer, writer, and publisher, educated to Master’s level. He is a keen advocate of DIY and home improvements.
Richard enjoys helping others to learn new skills and reach their goals and believes that passing his knowledge and experience on through his writing is an effective way to positively impact the lifestyles and well-being of others on a larger scale.