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MG MGB Technical - Vapour Blasting vs Bristle Blasting

Hi All,

I've searched the archives for threads on vapour blasting and bristle blasting of the MGB underside but there appears to be nothing on either subject.

I'm considering the merits of both as an alternative to the more common grit blasting method. My intention is to use one of these as preparation for the brush applied zinc treatment from Zinga. I would be very keen to hear from anyone who has experience in either underside vapour blasting or bristle blasting or those who have used Zinga.

I understand the vapour blasting technique is non-aggressive and achieves a very clean and satin finish; a caveat may be that the rougness profile may not be sufficient to provide adequate key for the Zinga. Regarding bristle blasting, such as that manufactured by MBX (see ebay link http://www.ebay.co.uk/itm/281214579777?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT), my concern is that cleaning progress may be very, very slow.

Many thanks,
Brian McIlvenna

(bmcilvenna@yahoo.fr)
Brian McIlvenna

We run grit blasting for our cast iron head work and for steel parts, use bead or vapour blasting or even bristle if you want more of a polish for ally products. I think you will find the methods you describe will be too slow. Soda blasting is getting common but I do not think aggressive enough for your requirements. Remember different grades of grit are avaialble and the aggressiveness also depends on the age breakdown quality of the grit....new grit quicker job but rougher...good paint grip surface though. We use 30/60 garnet grit for our work.

Peter
Peter Burgess Tuning

Peter,

Thanks for your input. How does grit blasting compare with the now illegal sand blasting for aggressiveness? What media is used for the grit and what would you expect the cost to be for the area that includes all the underside (minus the floor pans and sills), inner wings, underside of front wings, boot area and engine bay of an MGBGT? I expect the areas to be completely free of rust, with heavy underseal around the gear tunnel area.

Thanks,
Brian
Brian McIlvenna

Brian

I just had my roadster done yesterday using grit. Underside, inner wings, engine bay, sills. Didn't do the interior, inside the boot or any external panel - grit would be too harsh for those. The underside had caked on oil/grease in the tunnel area (looked like underseal) - the blasting fetched it off where a steam cleaner would not touch it.

Shell was completely stripped and on a rotisserie. I moved it in a 14' box trailer which made life easy.

Paid £300.

Richard

Richard Evans

Hi Brian

I have never used sand, but, I think sand would blunt very quickly, we use garnet which costs about £25 for 10kg. We only blast small items which fit in our blaster such as cylinder heads and sumps.

Peter
Peter Burgess Tuning

Peter,

Thanks for the update. I'm thinking of buying a rotisserie myself for cleaning access and applying the zinc, primer, underseal, and top paint coat; self-build kits are available on ebay for around £165. This would facilitate comfortable removal of the grease and underseal build-up in mainly the gear tunnel area.

I'm wondering about the logistics of moving a car supported on such a tool onto a trailer. I would imagine it requires 5 or 6 pair of hands to manoeuver the load safely up onto even a low loader. I think I need to do research on this.

Brian
Brian McIlvenna

Brian

I have my GT on one of these rotisserie' sat the moment. It makes it very easy to work on the underside in a much more comfortable fashion.

As it is made up of just two separate A frames connected to the bumper mountings it moves very easy on this axis, I would not however want to try to move it on mass to a trailer as the locking mechanism is quite flimsy as when it is balanced it takes little weight, but the forces on it when it is being moved could be significantly higher.

Regards

Tony
Tony Brough

Brian

I got my rotisserie off ebay last December for £125 - I was lucky but there are several good ones around for up to £250.

My rotisserie has wheels - swivel type with foot operated locking brakes. This means you can move in any direction, either end, very easily.

I too was pondering how to move it. I was going to take the body off the rotisserie, drop onto a flat bed then find a way of re-mounting at the other end. Then when I was looking at trailer options I thought why not just wheel it into a box trailer. My local guys have a WxLxH = 6x14x7 foot trailer with a loading ramp door. The rotisserie with car on it is 13'6" and about 5' tall.

It was perfect and really easy for two of us to pull the rotisserie, with body mounted, onto the trailer (probably could have done it single handed).

I then transported to a friends farm to steam clean it - took 1 hour including unload and reload of rotisserie onto the trailer. Then straight over to the blaster who loved the rotisserie as it made his job easy.

Here is a pic::


Richard Evans

and another:



Richard Evans


Pic = O/S sill, blasted and sprayed with UPOL Weld-thru primer. New sill planned.

I had the underside blasted and the engine bay. Not the interior or any top panels - we'll do that by hand. The UPOL primer (it is zinc based) was applied two hours after blasting and so far no rust (5 days).

Just started cutting out sills. This set up makes life easy. Planning to use UPOL tinted Raptor for underside then two-pack for top panels and engine bay.

Richard Evans

Richard,

You look to be doing the job well. The rotisserie looks the business. I'm going to look up grit blasting contractors in my area; my concern is that 20-gauge metal can very easily be deformed by the process.

I will need a rotisserie with wheels, just like yours, to enable the car to be moved onto a trailer. This is the time of year to do the research and make the enquiries.

Thanks,
Brian
Brian McIlvenna

This thread was discussed between 03/12/2014 and 07/01/2015

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