Removing paint from cast iron fireplaces

[Craig89]

Hello all, I have 3 cast iron fireplaces that are currently painted white, I would like these stripped back to natural cast iron. When I did my guttering and downpipes I used wire wheels and flap discs to great success but the fireplaces are quite ornate and intricate and I dont think I would get into all the nooks and cranies.

Does anybody have any experience of sandblasting fireplaces? An ex colleague of mine does agricultural sandblasting using an industrial compressor and kiln dried sand. I have used him before to do some car panels for me with great success just wondered if there are an issues with cast iron. The only problem I can forsee is obviously the sandblasting leaves a matt, dull grey colour and I would like them to be dark and polished but I ideally don't want to paint them. I would hope that running over them with the wire wheel after would brighten them up.

Any thoughts or experiences?

Thanks, Craig

 

[Monty]

Hi Craig,

That sounds like just the job for Kling Strip from Strippers Paint Removers at Sudbury https://www.stripperspaintremovers.com/

We used it on a cast iron fireplace also painted in white, but also multi-coloured earlier layers, and it came up like it had just come out of the foundry. Just pasted it on, covered it in clingfilm and removed the next day. The ornate details also remained really crisp, but I would imagine that with sandblasting you wouldn't get as nice a finish and the detail would be worn down a bit.

 

[Feltwell]

Hi Craig

Ages ago I bought a load of secondhand cast iron downpipes and guttering, and spoke to a local sandblaster - as it turned out it was the guy who does blasting for the Ketley foundry, where they make all the St Gobain "Classical Rainwater" range.

He strongly advised against blasting - he reckoned there was a 10% failure rate even on new items from the foundry. On old stuff he reckoned half of it would fail.

I know some fireplace restoration places do do sandblasting, but I'd be worried not only about failure but also about eroding the edges of details as Monty says. I'd go down the chemical route personally, Strippers of Sudbury are very helpful and do tester pots to try if it turns out that whatever paint in on yours doesn't react to Kllngstrp - it probably will!

 

[Craig89]

Thanks for the replies.

Feltwell, I knew I had read on here somewhere, at some point, that somebody had some bad experience of sandblasting cast iron.

I had considered the paint stripping approach but I did try a sample of Peelaway stripper when I stripped the paint off my bay window and it wasn't very successful and very messy.

Monty, how did you go about cleaning all the stripper and paint off the fireplaces after the application. Your experience does sound very appealing.

Thanks

 

[JBean]

We inherited a cast iron fireplace that had been painted white (and before that various other colours) and managed to strip it back to the original cast iron. There are photos here: https://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=15509&p=215491#p215491

We discounted sandblasting for the reasons others have given here, and used a combination of stripper and scrapers, moving from one system to the other as we felt the will to live draining away. The stripper (not sure if it was Kling Strip or not) was messy and smelly, and scraper slow and dusty.

But we are now very pleased we did it!

 

[CliffordPope]

I've stripped the paint from two fireplaces, and I got most of the paint off quite easily with just dry scraping. Fortunately both appeared to have dozens of coats of old paint, which made it much easier.. It was a revelation uncovering the detail that had simply been hidden under thick layers of paint.
For more stubborn portions, principally in corners and in the detail, I found just wafting a blowlamp over the surface was the best way. Just enough to soften the paint a tiny bit, followed by a smaller scraper or a metal pick for the finer detail.

 

[Monty]

Hi Craig,

I put lots of plastic sheet on the ground surrounding the fireplace, then most of the poultice came away when I peeled off the clingfilm. This I did with a little help from a paint scraper which I used to ease the poultice away, starting at the top and worked down - by doing this most of the used poultice fell onto the clingfilm I was slowly peeling downwards. When I had taken all of the clingfilm off the bulk of the now very messy gunk had come off with it. I then used a combination of damp sponges and old toothbrushes, including a mini wire brush that looks like a toothbrush. I had a couple of buckets with warm soap water (for rinsing out the sponges) and one with clean water for the final sponge down. From memory there were some bits of stubborn older paint in some of the detail so I used a bit more poultice and left overnight again and repeated the process, which did the trick. It was all a bit messy and unpleasant at the time, as with most jobs I seem to end up doing, but well worth it in the end!

All that said I was lucky that the type of paint on the fireplace was suitable for removal by klingstrip, as I know from experience that it doesn't work on all paint types.

 

[Craig89]

I think I will give the paint stripping a go, all the fireplaces are detached from the chimneys so I can take them outside and maybe pressure wash them off after to assist with the paint removal/clean up.

Monty or others any ideas on quantity of Klingstrip required for a fireplace?

Thanks

 

[Monty]

From memory, this was a few years ago now and in a previous house, I had a 5 litre tub. I do find the guys at Strippers very helpful and they have provided good advice on the phone and I'm sure they will recommend what quantities you need. In our new 'old' house I have two bedroom white gloss fireplaces to strip, maybe next year (or earlier if the list of 2021 jobs gets completed early :lol: ) and I will be calling them for advice.

 

[LadyArowana]

We did a chemical strip of a small white painted hob grate. The first product wouldn’t shift anything despite being left on over a weekend. I consulted Strippers and their reply is below. I believe the unsuccessful attempt was with Nitromors which has been reformulated to be less toxic, and my builder said it wasn’t as good as before. I will double check with him tomorrow as to what eventually shifted all the layers.

It’s definitely a worthwhile project, imho those cast iron grates look so much better in their original condition with a nice graphite paste polish. The extra detail on ours which emerged was lovely.



“ .................Typically it would be a gloss paint, in which case our product Kling Strip would be ideal as it is effective at removing multiple layers of paint in one application. It some, less typical cases, there may be a layer of emulsion which Kling Strip won’t work on, in which case you may require an application of a solvent paint strippers such as our Solvistrip.

In the first instance, if you are pretty confident that the paint is gloss I would go ahead and try Kling Strip: https://www.stripperspaintremovers.com/product/kling-strip/

If you take a look at the video on the page it will give you an idea of how it works, you could also take a look at the customer projects page for examples. https://www.stripperspaintremovers.com/customer-projects/

I hope this helps, please do not hesitate to contact me if I can be of any further assistance.

Kind regards,

Rosalie”

 

[a twig]

Or next time you are having a bonfire just put the cast iron on it for a bit :twisted:

 

[LadyArowana]

Just checked with my guys, and this is the stuff which shifted all the layers of old paint from our hob grate, https://www.amazon.co.uk/Rustins-S...strypit&qid=1610007673&sr=8-4&tag=googhydr-21

 

[RBailey]

Just checked with my guys, and this is the stuff which shifted all the layers of old paint from our hob grate, https://www.amazon.co.uk/Rustins-S...strypit&qid=1610007673&sr=8-4&tag=googhydr-21

I used some of the Rustins recently and wasn't that impressed. It did okay but not great even when I plastic wrapped and left the door overnight. Lots of scrapping was still needed.

 

[Craig89]

Currently got the Kling Strip on working its magic, will peel it off and pressure wash on Sunday I think.

 

[Craig89]

Well I cleaned all the Kling Strip off the fireplaces today and I'm very impressed indeed. Pulled the clingfilm off, which resulted in quite a bit of the stripper coming with it, scraped the remaining stripper off and finally pressure washed all of the residue off. They have all come up very well! The detail that has been revealed is amazing, and as mentioned by another, looked like its just come out of the foundry.

The large one has some small localised areas of paint remaining that will need scraping off and the small ones have both had some black spray paint on them at some point which the stripper hasn't touched. I have currently got some normal paint stripper working on these areas.

For my needs this has worked very well, if you had to do the whole process indoors I would imagine it could get very messy.

 

[Flyfisher]

We did a chemical strip of a small white painted hob grate. The first product wouldn’t shift anything despite being left on over a weekend. I consulted Strippers and their reply is below. I believe the unsuccessful attempt was with Nitromors which has been reformulated to be less toxic, and my builder said it wasn’t as good as before. I will double check with him tomorrow as to what eventually shifted all the layers.

The removed ingredient was dichloromethane (DCM), though I'm not sure what took its place, if anything.

Soon after it was removed I noticed a huge difference with Nitromors (ie useless) and ended up buying a bottle of DCM online to add it back and finish off the job I was working on at the time. I can't remember the exact price but I do remember being amazed it was so cheap, certainly less than a tenner for a 1 litre bottle. Checking online, DCM paint strippers are still available but only for professional users. So a bit like 'proper' creosote then

I only used about 1/3rd of the bottle and when finished I screwed on the lid very tightly and re-sealed the bottle in the thick plastic bag used for shipping. A couple of years later when tidying the garage/workshop I noticed the bottle was completely empty even though the thick plastic bag was still sealed with tape. The warning notes did mention something about it being highly volatile! :shock: