warwicksail
Well-Known Member
Does anyone know how much preasure will be required to blast my Iron keels, thing of buying a small sand blaster which will about 125 psi
Sand Blasting
- Thread starter warwicksail
- Start date
Watson47
Well-Known Member
warwicksail ... Not sure on the pressure required, but if you haven't got a blaster yet, then consider;
http://www.blastitclean.co.uk/
Very helpful & very knowledgable folk. Got a sand blasting kit from them about 6-7 years ago - just for external wood cladding but top class.
http://www.blastitclean.co.uk/
Very helpful & very knowledgable folk. Got a sand blasting kit from them about 6-7 years ago - just for external wood cladding but top class.
JohnTH
Well-Known Member
The domestic ones require large volumes of dry air as well as dry sand. This sounds easy but, in practice, it is difficult to have dry air.
Mine works for a short time and is great however, it clogs up very easily. In the end I had a professional do the job for me.
73s de
Johnth
Mine works for a short time and is great however, it clogs up very easily. In the end I had a professional do the job for me.
73s de
Johnth
Wino
Well-Known Member
Its not the pressure but the volume - From experience I would suggest a minimum compressor of 125 CFM (Cubic feet/minute) you could go a bit lower and use a smaller blast nozzle. this should be OK for smaller areas.
DinghyMan
Well-Known Member
You will need a BIG compressor to keep up with an air driven sandblaster - might be worth having a look at the pressure washer driven ones as they are cheaper but like air driven ones need nice fine dry sand such as block paving or silver sand.
Either method will be slow compared to getting a pro in.
Either method will be slow compared to getting a pro in.
pagoda
Well-Known Member
Dry blasting with sand requires a BIG compressor to work effectiely, with equally big quantities of the right kind of sand.
It's messy and noisy - you will not be popular. Doing the job requires proper industrial strength protective kit -or your lungs are at serious risk...
If you insist on DIY - then hiring a professional quality pressure washer for a week end might be workable. Paint and rust should be no problem. I've seen a professional washer lift chrome plate off steel... Getting it all dry and primed quickly might require thought though?
Or get pros to do the work and take the responsibility for the result?
Graeme
It's messy and noisy - you will not be popular. Doing the job requires proper industrial strength protective kit -or your lungs are at serious risk...
If you insist on DIY - then hiring a professional quality pressure washer for a week end might be workable. Paint and rust should be no problem. I've seen a professional washer lift chrome plate off steel... Getting it all dry and primed quickly might require thought though?
Or get pros to do the work and take the responsibility for the result?
Graeme
Jim W.
New Member
my experience
I just did the whole top deck of a 45 ft steel boat. I was able to rent a compressor used for construction. 4 cyl diesel unlimited volume at 100 psi. Take special care to choose your sand as this greatly reduces hazard."No Silica sand". I used large tarps to protect neighbors and gather used sand and paint for proper disposal. Immediatly apply a good epoxy primer. Sugest Interlux 2000e. see pics www.sailperseverance.net
I just did the whole top deck of a 45 ft steel boat. I was able to rent a compressor used for construction. 4 cyl diesel unlimited volume at 100 psi. Take special care to choose your sand as this greatly reduces hazard."No Silica sand". I used large tarps to protect neighbors and gather used sand and paint for proper disposal. Immediatly apply a good epoxy primer. Sugest Interlux 2000e. see pics www.sailperseverance.net
earlybird
Well-Known Member
A more civilised alternative to blasting might be to use a needle gun from a tool-hire shop. I've not used one myself, but an aquaintance did a while ago for a trailer and keels, he seemed happy with the results. I think it's slower and less drastic than blasting but comes without so many problems.
pagoda
Well-Known Member
Needle guns are pretty effective -most I've seen have been air powered, but there may be electric versions. You'll need hearing protection with these as well as the other PPE.
People who use them regularly have issues with vibration numbness - so don't do it for hours without breaks.
Graeme
oldsaltoz
Well-Known Member
.
Way too much because they will charge you by the day not by the hour.
A professional will complete an average cast iron keel in about 2 hours.
Also note:
Cast iron is porous and has pockets of contamination, so it's important that it is very dry before blasting and coating.
Using a needle gun will only drive particles of rust into the small holes in the casting and create conditions for more rusting, as will using a grinder or other rotary tools primarily because the surface is contaminated when re presented.
Blasting provides a constant flow of clean material to be presented to carry away any contamination. BTW using common sand is not legal due to the health hazard from silica.
Cast Iron will flash rust, that means it will start rusting the moment it's exposed to air so you you MUST coat it as soon as possible.
Blasting should be done to Class Two and a half, that's a uniform silver grey with no shadows.
The first coat is normally and epoxy resin or epoxy based product, it's very important that this applied as soon as possible after blasting. I don't wait that long, I follow blast nozzle and keep a few inches behind it and coat with epoxy resin working from top to bottom in 4 inch strips.
The next step is to fair the keel with a suitable product and apply 3 or 4 coats of resin, then 2 coats of High Build epoxy primer. When you are ready to antifoul apply another thin coat of high build and apply the antifoul when it's still tacky.
I hope this helps.
