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Sand her back or just blast?


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#1 cogspin

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Posted 23 February 2012 - 02:35 AM

Ladies and gentlemen, just a quick question.

Will sand blasting a 240z weaken the metal? and if I can save a dollar sanding it with whatever tools necessary, is it the same as blasting the car (albeit rougher and longer).

Regards,
Good kid, bright future

#2 nizm0zed

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Posted 23 February 2012 - 08:55 AM

To my understanding of it, no, blasting it wont weaken the metal, unless its riddled with rust, at which point its fubar anyway.
Depending on how its blasted though, it may warp the panels.
Soda blasting is the nicest of it all, but leaves a residue that can be a pain to deal with.
Sand blasting (garnet blasting) will strip quickly and leave no residue, but if the operator isnt careful it'll warp the panels (eg, roof, doors, large flat areas)
Acid dipping is the most effective way to get EVERYTHING off in one go, however i have heard that you'll have the acid solution leach out of seams for years to come.

Sanding, either by hand with with a DA orbital, will give you the best and most consistent control over the finish, depending on how deep you want to go, but it'll also take the longest.
Personally i hate sanding, it takes forever and drives me up the wall.
There is also chemical strippers, they'll remove bulk paint (and body filler) very quickly in localised areas and make a hell of a mess, but they'll still need finishing work in the area afterwards, eg, cleaning/sanding of residue.
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#3 thriller

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Posted 23 February 2012 - 12:39 PM

I don't think you'll ever be able to strip those intricate nooks and crannies on the inside of the car. Take off the hanging panels, strip them with a sander yourself and send the shell off to a blast. At least, that's what I'm doing.

#4 gilltech

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Posted 23 February 2012 - 08:05 PM

Quickest: get the shell & loose panels media blasted by someone who knows what they are doing, & who won't be tempted to rush the job (which can result in warped panels if too much pressure used) & immediately etch primed.
If you want to save money & have the time available then use 3M strip disks to take it back to bare metal yourself, & prime. Slow but effective. Do one area & prime, before starting the next. Fiddly around seams & brackets, you just have to be patient. Exposed edges damage the strip disks so assume you will need plenty of them. Leaves a nice buffed finish to the metal for etch primer application.
Personally I wouldn't use paint stripper.

#5 nizm0zed

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Posted 23 February 2012 - 08:40 PM

sounds like a man with experience....

Gilltech, how do those 3M strip discs go on somewhere like the middle of the roof?
Does the amount of heat they generate warp the panel? I would have thought it would.

#6 Rat1314

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Posted 23 February 2012 - 10:14 PM

I've now stripped 2 cars using the 'Brumby Strip it Discs' from Bunnings on a 4inch grinder and have had no issues with warping panels. Just take your time and work a section at a time. Also make sure you wear the appropriate PPE.

#7 PeterH

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Posted 25 February 2012 - 11:07 AM

I had this company do two guards and a hatch panel for me. I'm very happy with the work and they will  do the body shell when I have it ready . might be worth a look.

http://www.bicarb.com.au/



#8 xa1973

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Posted 25 February 2012 - 01:01 PM

I had this company do two guards and a hatch panel for me. I'm very happy with the work and they will  do the body shell when I have it ready . might be worth a look.

http://www.bicarb.com.au/


Over the years Ive used all the methods previously listed, this is by far the best method, modern technology is great......
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#9 gilltech

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Posted 26 February 2012 - 08:10 AM

The 3M strip disks don't generate much heat, the panels would get much hotter just sitting out in the sun.
You can buy them with the spindle built-in so once the disk is worn down the whole thing is a throw-away, but by far the more economical is to buy the spindle separately & the strip disks in a pack - just fit them up to your drill like a sanding disk. And there are different thickness disks. I prefer the thinner ones which can flex more.
If you happen to catch a raw metal edge you'll tear chunks off the edge of the disk. The trick is to work with the rotation of the disk when you get close to raw edges to minimise that. It's slow going if there are multiple layers to remove, but they remove bog & surface rust really well, & leave a clean slightly cross-hatched pattern on the metal surface. With a little practice you'll find they can last quite well.
Just make sure you wear a mask & most particularly eye protection! Chunks of paint, bog, rust & strip disk will fly off in all directions, often right at you.

#10 AndBir

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Posted 16 September 2016 - 01:07 PM

Is there any issue using a standard 4' / 5' angle grinder (@ 11 - 12,000rpm) and a strip it disk to remove paint from panels or should you spend extra $$$ on a variable speed angle grinder that enables you to set the speed from 2,500 - 11,000 rpm?



#11 Scoota G

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Posted 16 September 2016 - 01:27 PM

Is there any issue using a standard 4' / 5' angle grinder (@ 11 - 12,000rpm) and a strip it disk to remove paint from panels or should you spend extra $$$ on a variable speed angle grinder that enables you to set the speed from 2,500 - 11,000 rpm?

The paint will heat up and melt to the disc instantly.



#12 Dionysus

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Posted 16 September 2016 - 03:27 PM

Why not use paint stripper?



#13 gav240z

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Posted 16 September 2016 - 04:45 PM

Why not use paint stripper?


Messy and a pain in the arse...

I found these guys recently.
http://www.theblastfactory.com.au/
http://www.theblastf...arnet-blasting/

I find using strip discs takes a very long time...

RetroZ suggested using paint stripper and then a gerni or high pressure washer to blast off the paint. I haven't tried it yet but could be a good solution.

#14 nizm0zed

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Posted 17 September 2016 - 11:15 AM

I have since heard of a trick to use with paint stripper, but I have never tried it.
I have this feeling I may have even read about it on here, with Sirpentz describing it?

Anyway, what you do is rough up the paint with a coarse sandpaper, just enough to score up the paintwork, then paint the stripper over the area.
Then you use a large garbage bag over the top of the stripper, tape it down on the edges so it doesnt fall away.
The stripper does its job, especially well once the paint is scored up, then as it all comes off it sticks to the garbage bag.
Give it several minutes then lift the bag away with most of the paint and residue coming with it.
Obviously then you need to clean off and sand away any residue before wiping down with wax and grease remover.


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#15 Sirpent

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Posted 17 September 2016 - 01:46 PM

I have since heard of a trick to use with paint stripper, but I have never tried it.
I have this feeling I may have even read about it on here, with Sirpentz describing it?

Anyway, what you do is rough up the paint with a coarse sandpaper, just enough to score up the paintwork, then paint the stripper over the area.
Then you use a large garbage bag over the top of the stripper, tape it down on the edges so it doesnt fall away.
The stripper does its job, especially well once the paint is scored up, then as it all comes off it sticks to the garbage bag.
Give it several minutes then lift the bag away with most of the paint and residue coming with it.
Obviously then you need to clean off and sand away any residue before wiping down with wax and grease remover.

 

Yes you are correct Alen ;)

 

Also, heat helps the process, so having the car or panels out in the sunshine will help, the bags contain the chemical evaporation of the stripper allowing it to stay wet for a lack of a better term and act quicker and more effectively.

 

Have fun ;)

 

P.S.

 

When preparing the paint for the stripper, the more scoring of the surface the better and we used to use a scew driver to get through the paint in random long scratches (taking car not to leave a dent) to reach metal, this allow the stripper to reach the metal quicker the work from under the paint.


Edited by Sirpent, 17 September 2016 - 01:49 PM.


#16 EJ101

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Posted 18 September 2016 - 10:05 AM

problem with sanding at home is obviously time and patience, both of which I don't have. So you end up rushing and cutting corners and telling yourself "that'll do",and, if you live with a cleanliness freak, the dust and mess generated will drive her (or him) nuts, which will of course will come back on you. By the time you've finished doing it yourself you'll probably have ended up spending a thousand bucks on sand paper, strippers, chemicals, tools etc etc.



#17 daretobedifferent

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Posted 24 September 2016 - 08:00 PM

It honestly depends on how much rust/paint/bog the car has and how much of a perfectionist you are.

 

The way I'm restoring mine is;

 

Step 1. Strip the car bare

Step 2. Remove all the rubber seals and glue with a wire wheel

Step 3. Search for any bog and rust, by manually sanding down all the exterior panels (mainly roof, quarters and rear beaver panel). 99% chance there will be no bog placed on the interior / underside / engine bay of the car as there is no point.

Step 4. Cut out any major rust that you can find.

Step 5. Think of any repairs you'd like to do and get those panels removed as well (e.g. replacing the floors, rear quarter, etc).

- Remember to brace the car by welding steel box section if necessary. 

Step 6. Then media blast.

 

You can always media blast the car first, but this way

1. All the bog and most of the major rust sections have been removed prior to blasting

2. You can access areas of the car, you might not have had access to, if you decided to blast the car first.

3. You've got a better chance of getting all the media out this way post-blasting. 


Edited by daretobedifferent, 24 September 2016 - 08:07 PM.

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#18 AndBir

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Posted 24 September 2016 - 09:53 PM

It honestly depends on how much rust/paint/bog the car has and how much of a perfectionist you are.

 

The way I'm restoring mine is;

 

Step 1. Strip the car bare

Step 2. Remove all the rubber seals and glue with a wire wheel

Step 3. Search for any bog and rust, by manually sanding down all the exterior panels (mainly roof, quarters and rear beaver panel). 99% chance there will be no bog placed on the interior / underside / engine bay of the car as there is no point.

Step 4. Cut out any major rust that you can find.

Step 5. Think of any repairs you'd like to do and get those panels removed as well (e.g. replacing the floors, rear quarter, etc).

- Remember to brace the car by welding steel box section if necessary. 

Step 6. Then media blast.

 

 

Yep, I think this is the approach I will take. It should be an interesting learning experience!






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