Shot blast or Dip & strip..?
Discussion
I'm sure this has been asked many times....I've just started a resto on my Austin Healey 100/6. I need to remove the old paint & muck from the chassis & tub.(I'm removing the front & rear wings, front & rear shrouds & will strip these by hand) I cant decide should I have it shot/media blasted or a chemical dip. Has anyone had experience with this ? What are the pros & cons, cost implications etc...
Depends how rusty it is internally, or if you purely want to prep it for paint IMO.
Media Blasting (if done correctly, with the right media) will be cheaper and leave you with a nice keyed surface for the first coat (Etch Primer or Epoxy?). If done incorrectly it can warp panels (unlikely nowadays) and can leave residual media in a lot of the nooks and crannies (meh). It also won't be easy to get into any areas not directly visible (inside box sections etc), so you will need to consider treating/protecting those to insure you don't have rust working away in there you haven't seen.
Chemical dipping (generally using either Phosphoric or Hydrochloric Acid) is more expensive but, if pilot holes are drilled in box section etc, will get into all the hidden crevices, take everything back to bare metal and remove rust/filler etc (although you'd still be wise to waxoyl/dinitrol those areas later as there is a chance that some rust may remain). Depending on coy they can then apply a variety of protective/primer coats. Most of them recommend an initial dip/coat, then get the shell back to you for any bodywork, before dip/coating again, which again makes it more pricey than Media Blasting. There are also some reports of rust surfacing out of hidden sections later; the general opinion seemed to be that this was probably rust that the dip hadn't reached, which hadn't been covered later - hence my comment about wax/dinitrol etc, but there was also an opinion that it was residual acid that had leached out. I don't have direct knowledge of that, though.
TL:DR:
Media: Cheaper, Visible areas only, may leave residue and consideration should be given to further protection.
Dipping: Expensive, but comprehensive and needs an immediate dip coat of epoxy/primer/etc to seal the fresh metal.
If it were me, if there's a lot of rust/filler and the car needs a lot of bodywork, then I'd dip/coat. If it's fundamentally sound and you just need to paint it, with a bit of light bodywork, then I'd media blast. Regardless, I'd make sure to fully protect/treat all the hidden areas after paint.
All IMO
Media Blasting (if done correctly, with the right media) will be cheaper and leave you with a nice keyed surface for the first coat (Etch Primer or Epoxy?). If done incorrectly it can warp panels (unlikely nowadays) and can leave residual media in a lot of the nooks and crannies (meh). It also won't be easy to get into any areas not directly visible (inside box sections etc), so you will need to consider treating/protecting those to insure you don't have rust working away in there you haven't seen.
Chemical dipping (generally using either Phosphoric or Hydrochloric Acid) is more expensive but, if pilot holes are drilled in box section etc, will get into all the hidden crevices, take everything back to bare metal and remove rust/filler etc (although you'd still be wise to waxoyl/dinitrol those areas later as there is a chance that some rust may remain). Depending on coy they can then apply a variety of protective/primer coats. Most of them recommend an initial dip/coat, then get the shell back to you for any bodywork, before dip/coating again, which again makes it more pricey than Media Blasting. There are also some reports of rust surfacing out of hidden sections later; the general opinion seemed to be that this was probably rust that the dip hadn't reached, which hadn't been covered later - hence my comment about wax/dinitrol etc, but there was also an opinion that it was residual acid that had leached out. I don't have direct knowledge of that, though.
TL:DR:
Media: Cheaper, Visible areas only, may leave residue and consideration should be given to further protection.
Dipping: Expensive, but comprehensive and needs an immediate dip coat of epoxy/primer/etc to seal the fresh metal.
If it were me, if there's a lot of rust/filler and the car needs a lot of bodywork, then I'd dip/coat. If it's fundamentally sound and you just need to paint it, with a bit of light bodywork, then I'd media blast. Regardless, I'd make sure to fully protect/treat all the hidden areas after paint.
All IMO
I've looked into this for my own project and got very mixed messages regarding dipping. I've spoken to a few who have done and said they wouldn't do it again and who had problems from what they report as acid not being washed out correctly, to the shell being handling damaged during the process. I notice some people doing the acid dipping don't do an dip e-coat but are spraying a primer that will need careful attentions to all those box sections and hidden areas
I would agree with the other post saying it depends on how bad the car is, and if being really bad then dipping it to make sure every ( box sections ) are cleaned. Some simply wont need that and if you are removing the other panels and just have a tub, the downsides of damage of blasting delicate panels is almost removed in your case, plus of course blasting is flexible and you can specify areas you want blasted and those you may want to strip yourself.
Talking of blasting, what's going on with this blasted E-Type shell ??
https://www.facebook.com/MSBPCL/photos/pcb.8384248...
Another horror shell full of filler.
https://www.facebook.com/photo.php?fbid=1049803671...
I would agree with the other post saying it depends on how bad the car is, and if being really bad then dipping it to make sure every ( box sections ) are cleaned. Some simply wont need that and if you are removing the other panels and just have a tub, the downsides of damage of blasting delicate panels is almost removed in your case, plus of course blasting is flexible and you can specify areas you want blasted and those you may want to strip yourself.
Talking of blasting, what's going on with this blasted E-Type shell ??
https://www.facebook.com/MSBPCL/photos/pcb.8384248...
Another horror shell full of filler.
https://www.facebook.com/photo.php?fbid=1049803671...
Here is a link to the restoration of my E type. We went down the dipping route.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
Paracetamol said:
Here is a link to the restoration of my E type. We went down the dipping route.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
Who did the dipping ? Is it going for a re-dip and e-coat or sprayed epoxy ?http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
Deptford Draylons said:
Talking of blasting, what's going on with this blasted E-Type shell ??
https://www.facebook.com/MSBPCL/photos/pcb.8384248...
Another horror shell full of filler.
https://www.facebook.com/photo.php?fbid=1049803671...
Wow. https://www.facebook.com/MSBPCL/photos/pcb.8384248...
Another horror shell full of filler.
https://www.facebook.com/photo.php?fbid=1049803671...
I know a chap who had a BMW shell dipped and was very happy with the results, several years later he still hadn't had the "leaking acid" horror story. I had a look at SPLs web site recently, and noticed they seem to talk more now about drilling access and drain holes in box sections, not sure whether that's in reaction to negative stuff. I have heard things about shell damage and the like, but bad news gets reported much more than good.
Deptford Draylons said:
Paracetamol said:
Here is a link to the restoration of my E type. We went down the dipping route.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
Who did the dipping ? Is it going for a re-dip and e-coat or sprayed epoxy ?http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Here is the company that undertook the work.
The company restoring my E Type swear by this method.
http://www.surfaceprocessing.co.uk/for-cars.html
Yes. the car will go back and then be re-dipped and e-dipped after repairs...
I think the risk of accidental body damage is just one of those things that you have to be prepared for - it could happen at any stage of a restoration and, so long as you do your homework and use a company with a good record, you should be fine in that regard.
If I were dipping I'd make sure that the coy doing it thoroughly rinsed/flushed the chemical afterwards and, even if it's been dipped in epoxy, would still put extra protection in all the hidden areas as soon as possible - all it takes is one air bubble to form inside a box section and there'll be no protection deposited there. Even if they drill sections it 'may' happen, so best to act as if it have and then not worry.
That all said, my main point is still it's a sodding expensive process, so unless you're building a show car, or are happy with spending that amount of money very early on, or there's loads of rust in the first place I'd blast.
If I were dipping I'd make sure that the coy doing it thoroughly rinsed/flushed the chemical afterwards and, even if it's been dipped in epoxy, would still put extra protection in all the hidden areas as soon as possible - all it takes is one air bubble to form inside a box section and there'll be no protection deposited there. Even if they drill sections it 'may' happen, so best to act as if it have and then not worry.
That all said, my main point is still it's a sodding expensive process, so unless you're building a show car, or are happy with spending that amount of money very early on, or there's loads of rust in the first place I'd blast.
There have been several cases of acid leeching out long after the car has been restored. If the car is dry stored and used only in the summer it may take years to happen.
At least one old thread on PH about it. The OP in that case had a disaster with a fully restored car.
I know of one case that ended up in court (the claimant won) and others that were settled out of court.
Personally I wouldn't touch it with a barge pole.
At least one old thread on PH about it. The OP in that case had a disaster with a fully restored car.
I know of one case that ended up in court (the claimant won) and others that were settled out of court.
Personally I wouldn't touch it with a barge pole.
A friend has just come to the end of the resto of his Sunbeam Lotus, the car was dipped and then subject to an "open panel" rebuild where it was reduced to a floor and firewall and rebuilt again with fresh metal where needed, there was still rust in plenty of the seams after dipping that was only discovered as spot welded seams were unstitched! Another friend had his ex works Sunbeam dipped and had acid leech. From the sounds I'd go for open panel skipping any acid as it wasn't the total answer and can go very wrong, as with any bodywork there is never a quick fix.
I have too looked at this with my 1966 mustang that is virtually rust free CA car all original.
The dipping and E-coat SPl do is what i was going to do. I really like the thought of stripping it back and getting that lovely E-coat all into the nooks and crannies.
I have spoken to them on the phone and in fact have had some doors done by them in the past. They can not guarantee 100% rust removal especially in places where you can not see IE A/B pillars inner sills etc. I also dont believe they can guarantee full coverage of the E-cost in these areas either.
The other thing they sort of dont tell you is this.
Yes they like to strip the shell and give it you back (stage 1) and you do the repairs then they will re-dip again before E-coat dip. The thing is it's not the same process as stage one! as if you have fitted new panels that have that black coating on this has to be removed as the stage 2 "Prep" dip will not remove it, so will need a stage 1 doing again.
The other issue is this and i am not 100% sure now but they did not E-coat the shell on their premises it had to be shunted out to a different place via lorry so the and not done and the same time as the stage 2 "prep" dip which to me could introduce surface rust.
The other points are they only pressure wash the shell of with clean water from a jet wash IE a guy with a lance has to make sure all the acid is out of the shell, so how does the get into the inner sills, the A and B posts.
I think is has it place but not on "good" shells that have minimal rust. It is more to get it stripped to see what you are working with.
With the mustang i am going to give them the doors, wings and boot to dip and E-coat. Infact i have already had the wings and doors dipped already as i needed to do some dent repairs to them.
I will put the shell on a spit and get it blasted and Epoxy primered all at the same location on the same day.
The dipping and E-coat SPl do is what i was going to do. I really like the thought of stripping it back and getting that lovely E-coat all into the nooks and crannies.
I have spoken to them on the phone and in fact have had some doors done by them in the past. They can not guarantee 100% rust removal especially in places where you can not see IE A/B pillars inner sills etc. I also dont believe they can guarantee full coverage of the E-cost in these areas either.
The other thing they sort of dont tell you is this.
Yes they like to strip the shell and give it you back (stage 1) and you do the repairs then they will re-dip again before E-coat dip. The thing is it's not the same process as stage one! as if you have fitted new panels that have that black coating on this has to be removed as the stage 2 "Prep" dip will not remove it, so will need a stage 1 doing again.
The other issue is this and i am not 100% sure now but they did not E-coat the shell on their premises it had to be shunted out to a different place via lorry so the and not done and the same time as the stage 2 "prep" dip which to me could introduce surface rust.
The other points are they only pressure wash the shell of with clean water from a jet wash IE a guy with a lance has to make sure all the acid is out of the shell, so how does the get into the inner sills, the A and B posts.
I think is has it place but not on "good" shells that have minimal rust. It is more to get it stripped to see what you are working with.
With the mustang i am going to give them the doors, wings and boot to dip and E-coat. Infact i have already had the wings and doors dipped already as i needed to do some dent repairs to them.
I will put the shell on a spit and get it blasted and Epoxy primered all at the same location on the same day.
I've had dipping Nightmares
Never again. I've restored many cars since and I will only ever get them media blasted. If the resto is done properly most panels come off anyhow.
It's not worth the aggravation of dipping, imagine spending 100k having your dream car restored only to find after a few years it's worse than before you had it restored
Never again. I've restored many cars since and I will only ever get them media blasted. If the resto is done properly most panels come off anyhow.
It's not worth the aggravation of dipping, imagine spending 100k having your dream car restored only to find after a few years it's worse than before you had it restored
I worry about things like internal structures - imagine an MGB roadster, with a three-piece sill section. Let's say the inner sill has survived, but the outer has gone through but been replaced, and replaced well. Get the car dipped, having drilled access and drain holes in the sill section, and one result is that the castle (centre) sill section disappears because it was only just still there when the outer sill was replaced. Get the car back, and the only way you know for sure is to remove the outer sill anyway, but how many will do that if it all looks solid? So you have to start removing outer panels to see the internal structure is still sound, at which point a blaster could get in anyway.
MGB perhaps a bad example given the panel availability and cost, but the only example I can think of as I haven't seen many cars in that stripped down state.
MGB perhaps a bad example given the panel availability and cost, but the only example I can think of as I haven't seen many cars in that stripped down state.
Actually, I think they used these guys
AS per their website...
The Enviro-Strip approach to car paint decontamination offers a number of key advantages over shot blasting and chemical stripping:
No harsh chemicals are trapped in the seams & box section which can cause issues later in life
No indentation to the shell from shot blasting
No sand / grit trapped in seam joints
Saves time and money for the customer when the shell goes into the paint shop
The body shell stays on one secure process frame throughout the process eliminating any damage to the shell
http://www.envirostripukltd.com/industrial/auto-re...
AS per their website...
The Enviro-Strip approach to car paint decontamination offers a number of key advantages over shot blasting and chemical stripping:
No harsh chemicals are trapped in the seams & box section which can cause issues later in life
No indentation to the shell from shot blasting
No sand / grit trapped in seam joints
Saves time and money for the customer when the shell goes into the paint shop
The body shell stays on one secure process frame throughout the process eliminating any damage to the shell
http://www.envirostripukltd.com/industrial/auto-re...
Paracetamol said:
Actually, I think they used these guys
AS per their website...
The Enviro-Strip approach to car paint decontamination offers a number of key advantages over shot blasting and chemical stripping:
No harsh chemicals are trapped in the seams & box section which can cause issues later in life
No indentation to the shell from shot blasting
No sand / grit trapped in seam joints
Saves time and money for the customer when the shell goes into the paint shop
The body shell stays on one secure process frame throughout the process eliminating any damage to the shell
http://www.envirostripukltd.com/industrial/auto-re...
My concern with this process is they put the shell in a big oven to "burn off" the paint and underseal the temp is quite high i wonder if they get any panel distortion AS per their website...
The Enviro-Strip approach to car paint decontamination offers a number of key advantages over shot blasting and chemical stripping:
No harsh chemicals are trapped in the seams & box section which can cause issues later in life
No indentation to the shell from shot blasting
No sand / grit trapped in seam joints
Saves time and money for the customer when the shell goes into the paint shop
The body shell stays on one secure process frame throughout the process eliminating any damage to the shell
http://www.envirostripukltd.com/industrial/auto-re...
Deptford Draylons said:
Talking of blasting, what's going on with this blasted E-Type shell ??
https://www.facebook.com/MSBPCL/photos/pcb.8384248...
Looks like someones used a screw-in slide hammer to repair some damage. Pretty shocking!!https://www.facebook.com/MSBPCL/photos/pcb.8384248...
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