To blast or not to blast ?

[richardhealey]

Hello everyone !

 

I am just about to start the restoration of a '73 TR6. I am the second owner and have bought the car partially stripped - the chassis having been already restored and most of the suspension strenghtening plates have already been added. So thankfully, not too much work to be done here.

 

However, I am not quite sure how to tackle the body. The sills and floors are sound, but there are some small areas of surface rust around the gear box tunnel and a bit of work will needed to be done around the lights and frount valance - which has a few, quite small, rusty holes. However, apart from this the paint is remarkably sound.

My question is, based on that fact that I want to change the colour from Magenta (sorry, but yuk!) to red and that most of the paint work is unblemished and unmarked, should I get the body blasted once I have made all the repairs or just flat-back the paint that is already there (more paint the better?) and paint on top of it??? I realise of course that it is critical that the new paint is compatible with the original.

 

So, blast or not to blast ?

 

Thanks in advance,

Rich

[Guest ron]

In your situation I would take it back to bare metal, then you know exactly what you have, no hidden rust to pop out a couple of years down the road, plus if you are changing the colour it gives you pucka job.

If you're starting a complete resto and intend keeping the car longterm, the one piece of advice I can give you is don't cheapskate on anything, you will only regret it later.

Ron

[tim_trinda]

If you do decide to blast it select your blaster with care, over vigorous blasting can cause indentations or stretch large panels i.e. bonnet, roof, boot. A friend of mine has just had a body blasted and the paint shop had big problems in taking out the surface ripples.

 

And of course you need to get it primed ASAP after blasting.

 

=========

Tim

[Andy Moltu]

Get it blasted - that way all of the rust is removed.

The external panels are best removed from the tub for this.

The inner tub can be shot blasted but the outer panels may be better blasted with lighter materials such as plastic chips which pose less risk of distorting the panels. This is somtimes referred to as plastic stripping.

[jonlar]

Sorry to disagree Andy, don't get anything other than chassis shotblasted.  Any body parts bead/sand/gritblasted.   Panels will easily deform.

[Richard Crawley]

So, blast or not to blast ?

Hi Rich & welcome to the TR Forum;

Most definitely blast it but you MUST, MUST be VERY, VERY careful who you get to do it. Jonlar may have had a bad experience (& lots have) but if you select your “blaster” well he will do a superb job. After a trial run with the chassis (difficult to damage that) & then a couple of “test” panels, I trusted “Bob”, my selected Blaster (& his name really was Bob) with everything, including all my brand new panels  (I had doubts about the quality of the base primer) & even the bonnet. He did a first class job which you can never hope to equal with paint stripper & sanders. Get him to apply a Zinc Chromate primer immediately after as well, it should not cost much extra & it’s better than any DIY stuff you can buy.

But be prepared for some shocks when you get it back as blasting will get rid of all the rust & show up every last defect – & there will be more than you first thought!

[marvmul]

My TR6 had distorted panels because of blasting too vigourously : the rear wings had grown 10mm in length and I had to bring the rear deck higher to make the wings fit again.

The bonnet wasn't blasted, luckily : this is very difficult to repair when distorted.Also the boot lid.   There are other means to get bare metal on plain surfaces, but I think that without blasting the difficult parts, you can't get rid of all the rust.

[Richard Crawley]

My TR6 had distorted panels because of blasting too vigourously

Sincere sympathies but I stand by my advice that if you select someone who is familiar with working on cars panels as opposed to JCB’s & oil rigs you won't beat it.

[jonlar]

I don't think there's any real argument over the effectiveness of blasting, it's more the medium used, which is why I would suggest shot for chassis and bead (far less aggressive than shotblasting) for inner tub and panels.

[marvmul]

After the TR6 I've restored my TR3 : I had that car blasted too and this time the result was ok, I had learned my lesson and found someone who was experienced in blasting car bodies. I had someone zinc sprayed on it : a pistol  and a zinc wire is used  : the wire is melted and the zinc is sprayed on the panels with compressed air : it's very efficient against rust but I think epoxy primer is ok too : immediately after the epoxy primer you can spray the filler coat wet in wet : it's easy  at least for the inner body because it's not necessary to flatten the primer and filler. It's a two pack system and strictly speaking not allowed at home.

[Richard Crawley]

I don't think there's any real argument over the effectiveness of blasting, it's more the medium used

I don't have a clue what blasting medium he used, (although I think sand is actually illegal from a H&S viewpoint now). It's all down to selecting someone who knows what they are doing & having the confidence to rely on their experience; although I appreciate in this day & age it may not be easy to find someone you can trust!

[Roger H]

A quick check to see if your blaster knows what he is doing - take him a cast aluminium or alloy component (not from the precious TR, but a piece of junk from a scrapyard). Ask him to blast it for you. The way he responds should be self evident.

 

Plastic media blasting (PMB) is the only way to go in my opinion. It is soft enough to handle dissimilar metal types which may be adjacent to each other - (chassis/floorpan). It's also is less of a problem when trying to flush/blow out those last little bits that are sitting in the sills, chassis rails, bonnet/boot frames, doors etc. It can clean metal of paint while leaving rubber trims unharmed (although you would not do it that way). If you blast cast aluminium, (trailing arms come up beautifully), the PMB actually 'seals' the surface rather than opening up honeycombing in the casting which grit or mineral sand blasting does. Ultimately, it will come down to the operator on the day. Take sample bits - test run - check the different finishes etc.

Priming immediately after blasting is essential as oxidation starts as soon as an area is finished. If they leave it for a couple of hours before priming, you will find out in a years time when it's too late!

 

I sacrificed a day and a couple of cartons, stayed out of the way (outside the booth), but made sure that all was done the way I wanted at each step. If they won't let you be there, be careful.

[marvmul]

Because of the countless warnings against spraying two pack at home, I think accidents are very rare. Does someone know of accidents? What are the actual health risks?

One out of two smokers will die of the cigarettes and amongst the non-smokers the number of victims of cigarette smoke is about the same as road accident victims.

What is the risk of spraying two pack at home, knowing most people are cautious : less than one in a million? The harm done to the environment seems to be a real argument, not the personal risk. This is the warning on the two pack products I use: 'Use only in well-ventilated areas. In case of insufficent ventilation, wear suitable respiratory equipment. Do not breathe gas/fumes/vapour/spray. May cause skin sensitisation. Flammable'. Rather moderate warnings, isn't it?

What about the modern water based spray products?

[Richard Crawley]

What are the actual health risks?

Cyanide poisoning; at best sensitisation & at worst a painful, slow death!

[jemgee]

The H&S warnings on any packages tend to be fairly low key wording (other than the skull and crossbones variety!). The clue to it is to ask the manufacturer for COSHH sheets on the product. When you read those they often result in the opposite impression!

[Taffy TR Man]

Having just stripped a Six back to bear metal by hand I can certainly sing the praises of taking everything off - tiny rust  areas appear as if by magic and areas like the front wing / sill joint will pose all kinds of questions once you have the covers off - even 25 year old paint covers a multitude of sins. You'll also uncover deep sediments of old filler if you're really lucky...

 

I can't comment on blasting other than there seem to be alot of 'rules' around 'getting it done properly' - a task always easier to perform in hindsight..!

 

About a gallon of paintstripper, 200 sheets of various grade wet & dry and tremendous amounts of "just a little bit more and I'm done" will see the job through with no panel distortion and only marginal mental distortion... It's one of those character building jobs but it looks bloody marvellous when it's done.

 

Personal opinion in hndsight - back to bear metal, strip the major panel areas with stripper and bead blast the difficult bits like the sills, shut lines, under the bonnet and boot and the floorpan etc These areas are rigid and unlikely to do anything nasty even if a heavy handed boulder blaster is weilding the gun..!

 

T

[reg brg]

How do you know who is good and who is,nt ??

I stripped mine with paint stripper and wiped it down with acetone you don,t get distortion that way.

It takes time but at least you did it yourself.

Reg Bowler

[jean]

Marmul is speeking about spraying 2 pack at home, not pro's

who are doing it every day.

I did spray/paint 2 pack at one or another occasion, I'm still alive, many of my friends are dead and they never touched any paint  

Shall we ask our, knowing everything, public service experts

to stop polution and the use of 2 pack also in the rest of the World, to say India/China/Middle and South America and Indonesia. These are the places to where our Industry goes to continue poluting the World. Or do WE live, maybe, in a different Biosphere      ???

Jean

[Guest ron]

Jean

I did a lot of things in my youth that with the benefit of hindsight and middle age I wouldn't repeat, but just because I survived doesn't make them OK.

Can I just reinforce what Alex Pringle has already said:

Spraying 2 pack paint at home is DANGEROUS to your HEALTH,

ANTISOCIAL, unless you live in the back of beyond

and probably illegal into the bargain.

Ron

1975 TR6 in Sapphire Blue [cellulose]

[Guest Neil Russell]

It is interesting to read the comments surrounding the use of paints. Some people seem to think that 2 pack is lethal, whereas cellulose is not? In my time I have used both materials, and to be honest BOTH are just as lethal in the hands of the novice. 2 pack is an Isocyanate based chemical system, involving paint, thinner and hardener, this causes a chemical reaction which drys the paint, cellulose and enamel paints involve mixing with cellulose thinners which allows the medium to be applied, the cellulose then evaporates and allows the paint to air dry.

 

When applying Both types of paint, airborne pollution is given off. something like 65-70 % of a cellulose mix is lost to the atmosphere, compared to something like 30-40% of 2 pack. This is where the danger occurs.

 

People seem to delude themselves that cellulose is less deadly than 2 pack. this is utter nonsence, Both are carcinogenic, and they both have severe side effects if inhaled.

 

Who has applied etch primer to their car? If so then you have used a 2 pack product. people often forget about primers.

 

people also see the word cyanide and convince themselves that the product is more dangerous than cellulose. a similar fear exists with asbestos in the building industry, even though most houses built in the late 60's and 70's have it.

 

One can argue that you are doing less for the environment by using a cellulose based product than a 2 pack variety because the airborne particles can travel much further in the atmosphere before flashing off.

 

It like everything else is about common sense. My old garage was big, secluded from neighbours and as such I could use cellulose or 2 pack paint. my new one isn't therefore i will have to get used to the idea of others painting my cars.

 

In either case if you are using cellulose or enamel do it sensibly and wear a very good quality mask. fume masks are available for the occasional user. the airfed masks used in the pro re-finish industry are used because the operator is in contact with noxious substances every day, not once in a blue moon as we are.

 

Neil.

[richardhealey]

Hi everyone,

 

Just a quick note to thank everyone for their input and advice. We did, err, get slightly off topic towards the end, but I understand why!

 

It seems the vast consensus of opinion is to get the body tub blasted, which I will do. I will use elbow grease for the panels.

It seems that the real hard work is going to be to find a blaster who knows what he is doing!

 

Anyway, thanks everyone for their input!

cheers,

Rich