The Company of Choice has decreed that no more cup brushes will be used on the boats. Hmmm?
Get them to buy a bristle blaster.
That’s because the coatings specialist we have says it damages the surface of the steel causing paint failure to worsen. I’ve had this discussion with him and it will be a process as we change from international paints to Carboline products. The painting process is going to change but when done properly it should hold. Some issues on the new boats can be traced back to initial application during construction.
What do they recommend instead? We’re using flap disks for the most part, easier to blend in with surrounding finishes. Waste of time and money to be done onboard but what do I know.
Too smooth a profile will result in poor adhesion. My guess is that the belief that using a cup brush might get rid of the rust but it also polishes the steel.
That bristle blaster actually looks like a great product compared to a grinder with wire wheel.
What’s the matter, what happened to the good old fashioned needle-gun? Keeping the captain awake on his off-watch?
sand blast when outside the port and the wind is blowing
Needle gun the scale, then grind the remaining rust to bare metal with an implement of your choice. Usually a wire cup brush, but As some are saying its maybe not the best for the job. 60-grit flap disks on a grinder are my new idea.
[QUOTE=Chief Seadog;143100]Too smooth a profile will result in poor adhesion. My guess is that the belief that using a cup brush might get rid of the rust but it also polishes the steel.[/QUOTE]
That is exactly correct. Heavy brushing polishes the surface too smooth. Cleanliness and an appropriate surface profile is necessary for proper coatings adhesion. Abrasive disk is far better, and a darned rough grit at that. The paint maker will specify the surface profile required for initial applications and repair touch ups.
Depending on the coating to be applied, a clean up with solvent may also be required just after confirming the surface profile is good. it is a bit time consuming, but the applied paints stay applied this way. For all yard works, be they touch up or grit blast in entirety, we specify the surface profile required (even for hand prep) and inspect to ensure it is actually met. A 3 x full coats + 3 x stripe coats tank grit blast and recoat job may have over 75 individual steps.
A top coatings contractor and good supervision by the paint contractor [U]and[/U] vessel owner is essential, as are the right tools, proper environmentals and a good man on the spray gun. We have contractors and supervisors we trust, we demand them by name and they produce outstanding results. it costs a lot, but skimping here never pays off. Too many morons and excuses out there, and it costs a boatload if it is done wrong.
PS - Always, always check your tank coatings within the warranty period and make claims as needed. These works can easily cost a half million to redo on a typical OSV.
Good paint data sheets and explanations are available online from most marine paint makers.
Example:
http://www.international-marine.com/supportadvice/application-guidelines.aspx
http://www.sigmacoatings.com/marine/downloads/
http://www.sspc.org/sspc-sp-11-power-tool-cleaning-to-bare-metal.html
This is a good course for marine personnel:
http://www.sspc.org/Marine-Coatings-eCourse
Great free guidance and photos here
And do not trust the paint maker’s man to do all the inspections for you.
Let them help figure out what is needed, then deal with it in house as much as possible. Obviously one needs to understand what is required and what it is you are looking at and for, but it is more politics of getting the steps followed correctly than it is a rockit science.
Some paint reps are lazy mouth breathers that do no good and can do harm, while others are A-1 top shelf.
You can suss out their work habits as you go and then run off the slugs without hesitation.
Tank coatings work and time out of service is too darned expensive to muck around with fools and liars.
Always observe your overcoat times, even on touch ups.
We see a lot of overcoat failures because the first coat was already cured and the top coat couldn’t tie in. Then it peels right off …