Hi all. I've been trying to remove some black Bitumen paint, Which some bright spark decided to paint on the gunwales of my narrowboat, instead of the usual gloss black paint on most boats. The methods I have tried so far is paint stripper. It only softens the surface.  A paint scraper and heat gun, No good that, as the bitumen turns to sticky gunge.  Random orbital sander, But the sanding discs get bunged up straight away. Same again with a 4.5-inch grinder. Before heated. the bitumen is very hard. It's impossible to smooth it out. I don't have access to a pressure washer or grit blasting. What can I try next? Or would I be able to apply glass paint over the bitumen. I am only asking out of desperation, as it has taken me nearly two days to strip it off, on one side of my 58 ft narrow boat. Thanks in advance Dave

I think you may need to find a high build undercoat to prepare the surface before sanding smooth, as presumably the gunwales may still have some bitumen and this won't accept a standard paint.

I cant see any way to remove the bitumen other than what you have done already.

If you want black, which would seem to be best, then it is possible that you could use a topcoat which is designed to be surface tolerant and won't fade.

I would look at SML Paints

Marine Paints section

Have a good read at all the different types of paint, and when you have found something that might fit, phone the Company and ask for technical help.

 

 

Edited January 27, 20251 yr by LadyG

Scabbler or needle gun.  A reciprocating scraper may work. 

If you soak rags in white spirit and lay them on the bitumen it will soften enough to be scraped off by hand.

Wire cup brush on an angle grinder. A bit slow going as the bitumen will melt under the onslaught, but it does come off and leaves a clean metal surface behind. If repainting with oil based paint I would be minded to wipe over with white spirit afterwards to dissolve any remaining traces.

How to get blacking off....SML paints....😜

3 minutes ago, matty40s said:

How to get blacking off....SML paints....😜

Is that sarcasm at Lady G love of SML (and I admit I have found them useful ) or are you trying to direct the OP to some literature?

I prefer that bit to be bitumen so if it was me I would leave it

Wire brush on grinder then clean off residue with rags soaked in Diesel which can then be used as fire starters. 

 

 

 

Then white spirit presumably. 

 

 

8 hours ago, David J Smith said:

Hi all. I've been trying to remove some black Bitumen paint, Which some bright spark decided to paint on the gunwales of my narrowboat, instead of the usual gloss black paint on most boats.  

You want the gunnels to be non slip not gloss. 

On gloss you will lose your foothold at the wrong moment. 

 

I did have gunnel tops in bitumen on the narrow as am fundamentally lazy but it is also quite durable and not slippery like gloss would be. 

 

Other option is to mix pet shop type  sand with the paint. 

8 hours ago, David J Smith said:

 instead of the usual gloss black paint on most boats. 

 

You'll find a variety of colours used to paint the gunwales of most boats, just as there are different colours used to paint cabin sides, roofs, etc.

 

Some people do use gloss paint for the gunwales and roof but if you're doing that you should mix in a decent amount of non-slip aggregate specifically sold for this purpose, or use sand on top of the paint and cover with more coats. I take the easier option and use International Interdeck. It's one of the only non slip deck paints I've found that a DIYer can make a decent job of without the aggregate looking uneven. It's only available in limited colours but you can add polyurethane gloss paint to it in small amounts to change the shade.

Tercoo discs work. 

A T handled scraper from Screwfix, or Toolstation is pretty  effective, particularly on older bitumen.

Follow up with a wire brush then wipe with kero.  Allow to dry well before priming.  Use a bitumen tolerant primer.  Zinser sell one I think.

M

 

 

I know the op said 'gunwales' but do you mean the vertical section from the top rubbing strake up to the edge you walk on?

Important point. That strip is often painted to look attractive sometimes in the same colour as the topsides. 

 

By 'gunnels' I was thinking side decks ie the flat surface one walks upon. 

 

'Gunnel' or 'Gunwale' is not in fact a deck as such. 

 

 

 

 

 

10 minutes ago, Mike Tee said:

I know the op said 'gunwales' but do you mean the vertical section from the top rubbing strake up to the edge you walk on?

 

Aren't they called "top planks" the term originating from wooden boats? 

19 minutes ago, blackrose said:

 

Aren't they called "top planks" the term originating from wooden boats? 

Think they went down the centre of the boat either on top of the load or on top of the hold on the masts

22 minutes ago, blackrose said:

 

Aren't they called "top planks" the term originating from wooden boats? 

 

Yes I think that is correct. 

 

As mentioned above 'top planks' also means the central narrow board walkway over a sheeted up hold on a canal Boat. 

 

 

 

So in a glossary of wooden Boat building terms the top plank would be what you said but in a glossary of narrow Boat terms it would be the other thing .

 

Room for confusion.

 

 

Or is it actually 'top strake' rather than 'top plank'. 

 

 

12 hours ago, David J Smith said:

Hi all. I've been trying to remove some black Bitumen paint, Which some bright spark decided to paint on the gunwales of my narrowboat, instead of the usual gloss black paint on most boats. The methods I have tried so far is paint stripper. It only softens the surface.  A paint scraper and heat gun, No good that, as the bitumen turns to sticky gunge.  Random orbital sander, But the sanding discs get bunged up straight away. Same again with a 4.5-inch grinder. Before heated. the bitumen is very hard. It's impossible to smooth it out. I don't have access to a pressure washer or grit blasting. What can I try next? Or would I be able to apply glass paint over the bitumen. I am only asking out of desperation, as it has taken me nearly two days to strip it off, on one side of my 58 ft narrow boat. Thanks in advance Dave

Why not just give it another coat of blacking, you will be forever touching it up if you use the boat. Lots of boats are blacked from base plate to side deck/gunwale above the rubbing strake 

I removed all the "blacking" from the top planks on Helvetia. and found that White Spirit was the best solvent. That was a traditional Bitumen. based product, and it may not work on more modern coatings, which may not contain bitumen, even though the term bitumen still seems to be the generic description used by most people.

I had the same problem.

I did it with a scraper. It was a horrid hard boring job so I did it over several years, doing a bit more as and when I was in the right mood.

4 hours ago, Bee said:

Tercoo discs work. 

They do- very well- but dont stand behind behind it without a face mask/fully hooded overalls etc as you end up with a very bitumened head instead- guess how I know this 😀

12 hours ago, hider said:

Scabbler or needle gun.  A reciprocating scraper may work. 

If you soak rags in white spirit and lay them on the bitumen it will soften enough to be scraped off by hand.

I agree. Using a scabbler I removed 20 years of bi annual blacking from my 55' nb sides (rubbing strake to baseplate). in one day. Hard,dirty work. I wore out a full set of tungsten cutters. I hired it from a long gone tool hire shop outside Uxbridge.