Steel Hull - Sandblasting

[KISS]

After blasting, you need to get the sand out prior to painting.

It's my understanding that this must be done quickly (otherwise the steel will begin to rust again), and thoroughly (even small amount of sand under the coatings = very bad).

So, what's the best way to do this...?

I presume you can't use water to wash it out (--> rust).

So, vacuum?

...but somehow I don't picture a vacuum doing a very thorough job.

What's the best practice here?

[Typhoon]

Originally Posted by KISS

After blasting, you need to get the sand out prior to painting.

It's my understanding that this must be done quickly (otherwise the steel will begin to rust again), and thoroughly (even small amount of sand under the coatings = very bad).

So, what's the best way to do this...?

I presume you can't use water to wash it out (--> rust).

So, vacuum?

...but somehow I don't picture a vacuum doing a very thorough job.

What's the best practice here?

I think your best bet would be to blow out of all the ribs and stringers until it has accumulated in the lowest part of the bilge and vacuum it from there .

Regards John

[Lepke]

After getting the big stuff with air or vacuum, wipe down with acetone or thinner for the paint you intend to use, ie, epoxy thinner, etc.

[KISS]

Thanks for the thoughtful posts fellas.

There's another thread on more or less the same subject, so I'll be commenting there going forward.

MODS, if you like, feel free to merge the threads.

[HoneyRyder]

I did this to my boat. After I blasted the inside (twice), I swept up the bulk of the grit, then vacuumed, then brushed down, then repeated several times.

It is important to make sure the temperature of the steel is high enough to take the epoxy, so I painted mine in late summer. It's true that the bare metal will start rusting again within 30 minutes or so of being freshly blasted, and some people use a heater inside the boat to keep it as warm as possible just prior to painting to keep it as dry as possible.

However, you can buy a special epoxy primer for raw steel, it is very thin, and it is designed to get well into the "pores" of the metal in order to get a good hold. It is not cheap, but if you are going to all this trouble then it makes sense to pay the extra to ensure a good job. The epoxy coat goes on over the top, and it is important to get your timing right here too; each successive coat of epoxy needs to be applied while the previous coat is still tacky, rather than hard/dry/fully cured. If you paint at this stage then the successive coats will form a chemical bond, instead of just a physical one.

I used the primary coat and then three coats of standard epoxy over that, and waited about 14 hours before each coat, but the waiting time will depend on the temperature where you are.

With the right application methods and right paint, it is supposed to be good for at least 30 years.

Good luck. It's a big job but well worth it.

[steamgoat]

When ,long ago, I built mine,I did both the inside and outside in sections so it was easier to deal with, blast a reasonable area,clean, prime then another section the next day.After it was all primed,major cleanup and topcoats.