Water Blasting

[Simon Hawthorne]

I am looking to strip paint and rust from a 55ft narrowboat and the dry dock won't allow sand blasting due to the mess. I don't blame them.

Has anyone experience of water blasting as an alternative and an idea of comparative costs?

[cuthound]

No experience of water blasting, but CO2 blasting  (beads of dry ice) works well as the beads melt and evaporate, leaving only the paint residue behind. No idea of cost though.

[ditchcrawler]

27 minutes ago, cuthound said:

No experience of water blasting, but CO2 blasting  (beads of dry ice) works well as the beads melt and evaporate, leaving only the paint residue behind. No idea of cost though.

If you have enough pressure it will clean it.

[David Mack]

A previous thread on the subject:

and a recommendation from that thread:

http://marinerepairs.co.uk/UHPBlasting.html

 

Maybe some others too at http://www.canaljunction.com/boat/cleaning.htm

[Simon Hawthorne]

Thanks David. Very helpful.

Just need to find someone a bit nearer to do the work.

[howardang]

On 21 June 2018 at 15:13, cuthound said:

No experience of water blasting, but CO2 blasting  (beads of dry ice) works well as the beads melt and evaporate, leaving only the paint residue behind. No idea of cost though.

I have used pressure washing to remove layers of paint/rust from the hulls of ocean going tugs, prior to painting. It worked very well down to shiny steel, but the equipment used was very much higher pressure than a domestic washer, and needed fully trained operators in appropriate PPI. The pressure was such that it was capable of cutting a breeze block in half, as they demonstrated for a party piece! We also used a water based primer coat to speed up the process.

 

It was done in a large dock at a time when concerns about pollution were not as strict as nowadays and if carried out on, say, a narrow boat on hard standing ashore, would require shielding to contain the rust/ paint flakes, and to keep spray water from contaminating any watercourse, including the canal.

 

I am not sure if it would be worth the bother.

 

Howard

 

 

 

[Dr Bob]

Grit blasting, if done right, gets you to a set standard used in the paint industry...i.e. SA2.5 which is then fine to apply paint to. This standard though assumes a roughness to the surface which you get with grit blasting. Normal water jetting will not prepare the surface well enough to achieve SA2.5 or anywhere near it. Ultra high pressure jetting will get back to bare steel but not the roughness.

Make sure you prepare the surface to the standard that the paint manufacturers state. This is one case where you do read the instructions carefully. 

[jddevel]

On 22/06/2018 at 23:01, Dr Bob said:

Make sure you prepare the surface to the standard that the paint manufacturers state

I seem to remember when painting a aluminium car that self etching paint was available to allow adhesion to the metal. Is it possible that this may be available as a primer for steel? Besides CO2 Soda blasting is also available. 

[Dr Bob]

6 hours ago, jddevel said:

I seem to remember when painting a aluminium car that self etching paint was available to allow adhesion to the metal. Is it possible that this may be available as a primer for steel? Besides CO2 Soda blasting is also available. 

I have not heard of any 'self etching' coatings for steel but if its a chemical reaction you are after then Red Lead paint is by far the best. I mean Red Lead not red oxide. Someone gave a link to someone in Bristol who sell it but it is expensive - £120 for 5Litres.