Sand blasting? want to strip my frame back

[Fishy]

really maybe I'll just use a wire wheel and paint it. It's just for an old MX'r so I need something fairly strong. How much does galv cost?

Give Metal Protection Ltd a call, they are in Penrose. Ph# 634 3600 they will be able to galvanize it.

[Hairy Buffalo]

You could also give the guys at Avondale Blast & Coatings a call as the guys there all own bikes and I know they have done a couple of frames.

Avondale Blast & Coatings LTD
74 Patiki Road
Avondale
Ph:828-0720

[maneac]

mate doz sand blasting up in kumeu buzy bee blasting 09 412 6262

[classic zed]

This is correct when powdercoating steel. It does need to galvanised before powdercoating to prevent rusting below the powdercoat surface causing the powdercoat to bubble and flake off.

I was told that my frame and things were dipped in some kind of etching wash to act as a primer, I know that it doesnt chip off very easily because I dropped the frame off the hoist, it hit the metal hoist before hitting the concrete floor, not a scratch, paint would have just chipped off.

[Fishy]

I was told that my frame and things were dipped in some kind of etching wash to act as a primer, I know that it doesnt chip off very easily because I dropped the frame off the hoist, it hit the metal hoist before hitting the concrete floor, not a scratch, paint would have just chipped off.

Yes products do go through a caustic etch this is one of the steps during pretreating process. The strength of the chemical etch is not all that strong however if you go to a general powdercoat plant that does mainly aluminium extrusions as aluminium is obviously a lot softer than steel and doesn't require it. So any plants that powdercoat mainly aluminium extrusions (as we do) advise to have the steel galvanized to prevent and corrosion under the powdercoated surface. There is always exceptions to the rule and we have powdercoated quite a few steel products with good results...... but time will tell if they stay that way.

[Crisis management]

I was told that my frame and things were dipped in some kind of etching wash to act as a primer, I know that it doesnt chip off very easily because I dropped the frame off the hoist, it hit the metal hoist before hitting the concrete floor, not a scratch, paint would have just chipped off.

Listen to Fishy, he is correct. I was the process engineer for the ford wheel powdercoating plant (several centuries ago) and have had a little to do with powder coating over the years which is why I raised this issue originally.
A paint surface is impermeable while powder coat is not, hence the need for galvanising. You can get the same effect with high build paints (Carboline was a manufacturer we used) but they are nasty to apply (isocyanates). I have used them for industrial machinery and plant which gets a real hiding and have never felt let down by the paint finishes.
I wouldn't panic about your frame rusting out but I would expect to look for some signs of rust staining in a couple of years time.

[cheese]

Hmm they can't galv a frame cause they need to drill holes to let it run out or something.....

Bum

I'm just going to paint the fucker myself.

[degrom]

Hmm they can't galv a frame cause they need to drill holes to let it run out or something.....

Bum

I'm just going to paint the fucker myself.

Sounds like they don't want your business. I don't like it when people is like that...

[AllanB]

Don’t go near galvanising on a bike frame. Hot dip galvanising is HOT and often ‘tweaks’ items during the process – the item is lowered into the very hot liquid bath so often warps it a bit. Not a big deal on a trailer frame or gate if it is out by 5mm once finished but shit on a bike frame. Also the process is fairly messy with pits and tails. In addition every single hole will be filled with galva and need re-drilling and threading, steering head would need the galv ground out.

The dipper who said drain holes would need to be drilled is correct as the heat build-up within a sealed hollow pipe in the dipping bath can explode the pipe.

There are spray-on applications but I know little about them.

I had crash bars, grab-rails and brackets I’d made on my previous bike power coated with absolutely no problem and they were still good after 20+ years (must have been the layers of polish ). A good powder coater will have suitable undercoats for each application, the one I use in Christchurch does bike frames, car components, wheels racing frames, trailers etc.

My advice is to call a few vehicle restoration companies and find out who/what they use. Also grab a copy of the British classic bike or similar as they have companies advertising re frame restorations and you could e-mail them for advice. I am certain the Poms powder coat their frames.

Phone Ken MacIntosh and ask who/what he uses on his Max replica frames - these get sent over the world.

[TLDV8]

Do not confuse hot dip galvanising with zinc spray...fwiw

I have prepped parts that have been hot dipped and powdercoated but that was for external fences which were box section.It would be overkill on a bike frame and a !@#$ to prep for coating. (imho)
I have frames done 20+ years ago still fine..also frames that were stripped and recoated after 10 years after being scrapped down to remove as much as the powercoat as possible to make the blasting easier.There was go sign of rust.

I have followed the same procedure for over 20 years.

I also sand or bead blast.The media is important.You do not want some clown to shot blast your frame.
I contact the powercoater to see when is suitable and work around that.
When the frame etc is blasted i mask what is needed,prepsol it and take it to the coaters.
A blast etch will out perform that crappy dip they use any time which is cost/performance based.
It has to be said the time span of a bare blasted steel surface before oxidation starts is fairly quick,a max of 12 hours or less.

King brothers blasters off New North road are very bike friendly but havn't needed anything done for a while.Smaller parts i blast myself.
*
I think i just used a months quota of "I"s

[Motu]

You can buy your own sandblaster from Repco or Mitre10 for $40 or less and do it yourself.I have,using dune sand I picked up off the beach.Slow....I've also cleaned frames with oxy/acet torch and a wire brush.Depends if you want the satisfaction of wasting your own time for small result,or paying someone else the pleasure.

[degrom]

5cm of the topic... Do anyone know of a place that stock sand blaster nozzles?

Please PM if anyone know.

Thanks.

[TLDV8]

You can buy your own sandblaster from Repco or Mitre10 for $40 or less and do it yourself.I have,using dune sand I picked up off the beach.Slow....I've also cleaned frames with oxy/acet torch and a wire brush.Depends if you want the satisfaction of wasting your own time for small result,or paying someone else the pleasure.

Going strong since 1993.... Some plywood and dowelling.The dearest part was the regulator...A pity the No 8 fencing wire outlook is slowly being eroded.

Time consuming as you say but it means things like carburetor's etc can be done with very fine media at very low pressure for that ace finish.

I use an old 2HP 12 CFM compressor.