To Blast or not - that is the question

[Paul_71]

I'm having mixed opinions on whether the Europa body should be media blasted (Soda). A good friend recommended not, which I trust his advice since he did go down this route and the garage then spent a long time filling the tiny pin holes.
A corvette body shop specialist told me yesterday I need to expose these holes to prevent air bubbles. He would use a spray on filler (from Germany to replace the Gelcoat) and block sand it, ready for the primer.
Can anyone share their experiences/ products? I just want to make sure which ever way I go (current mind set is to do the sanded route), the garage is doing it right.

Would appreciate your thoughts.

[EuropaTC]

I'll open by saying that I have no personal experience of soda blasting fibreglass, so my comments should be taken with that in mind.

My big concern would be less on the process, more on the guy doing it because I can see plenty of scope for damage to the fibreglass.  I'm sure things like line pressure and media are well known factors but we have the variable quality of the Lotus body and it's hand lay-up to consider in this case.  Personally I can see the process with metal panels but less so when there are so many variations with panel thickness ranging from 4-5mm to almost translucent in places on my car. 

As to whether you need to remove sub-surface voids, I can only think that relates to the paint process being used.

If it involves heat curing in an oven I can see that may cause any voids to expand with hot air pressure and break through the surface so maybe that's what your Corvette guy is concerned about. Our Lotus cars will originally have been finished in cellulose at ambient temperatures so it wasn't a problem back then.

I'm guessing the spray filler referred to is what most folks (including myself) use to obtain a smooth base for primer, but it's not a direct replacement for the gel coat.   I would apply it after repairs and on top of any gel coat as it's very good at filling small voids, scratch marks left from 80 grit paper, etc.

The big deal with any paint job isn't the paint, it's the preparation and a lot of that is time spent removing the old paint.   So that's why the pro shops are looking for ways to speed up this process and no doubt why they like media blasting. Whilst it takes me typically a week or more to get my cars to base fibreglass, they can blast strip the paint off in an afternoon, thus saving massive labor charges for their customers.  If you're using spray filler, then a couple of coats later and it'll be good for primer.

Assuming they know what they're doing with blasting, then I guess your next question should be  "what about the gelcoat cracks ?"   If they are proposing to take a car, blast & then simply spray filler, sorry but that isn't going to work.  It'll hide the cracks for 6 or even 12 months but I'll guarantee that just like Arnie, "they'll be back" 

Brian

[buzzer]

Definately care would have to be taken. And I think take careful note. Europa bodies are very very thin. Corvette Bodies are thick. Therefore as I see it on the Europa with blasting there is a huge risk of damage. Basically I would not compare blasting a corvette body with a Europa body.

[TCS4605R]

I am in the process of prepping for painting.  I'm planning on using single stage urethane without clear coat.  I removed all of the original paint and primer with 80 grit and a Merka DA sander that had a vacuum attachment to help control the dust.  I sanded down thru three stages of paint and primer - evidently the car had two paint jobs before I bought it in 1978.  On the doors and engine cover, I sanded down to a powder blue colored gel coat surface.  On a cover picture of an old ReMarque magazine, there was a picture of three Lotus Elans outside the factory in powder blue gel coat.  This stuff is extremely hard, but it can be sanded off.  I'm glad I sanded it off as I found a bunch of voids between the fiberglass and the gel coat - not bubbles but actual voids.  I have since sanded out and filled these voids with chopped fiberglass and polyester resin.  I also discovered over time, the thin fiberglass body changes shape.  My engine cover was about 3/8" lower than the fenders at the rear.  I brought the surfaces back even by adding fiberglass then body filler trying to keep the body filler as thin as possible.  I also spent a lot of time getting the gaps between adjacent panels even - 4 to 5 mm.  So, as far as soda blasting is concerned, I would avoid it as the fiberglass is very thin and is prone to change shape.  Sanding is super time consuming, but the results are worth the time.  After sanding, I applied 3 coats of 2-part black epoxy sealer, then sanded that with 180 grit to get it semi-flat, then applied 4 coats of high build polyester primer.  I then sanded the polyester primer using a powdered guide coat to get the surface perfectly flat and smooth with no waves, etc.  I had to repeat the polyester primer/block sanding several times as high and low spots appeared after a block sanding session - again, a ton of time.  Hopefully, I will get the car completed before I am too old to get into it.

Tom
74 TCS - 4605R

[Gmg31]

I had my body shell  soda blasted and I really wish I hadn't.  This started because the body shop who were planning to paint the car for me thought there was moisture in the gel coat and we agreed to soda blasting so we could get down to the gel coat and properly assess the situation.  Well once you get down that far the bubbles disappear any way so you can't tell whether they were in the paint or in the gel coat.  The soda is very gentle and it doesn't damage the main body but it does widen any small holes and it does leave a rippled effect on any filler that was under the paint. It also fills your car with soda and even now months later every time I open a door soda falls out onto the floor.    Finally my biggest regret is how much it costs.  It is a very expensive process the soda itself costs a fortune, mine cost me £800 and to be honest once we realized it wasn't going to be of value he stopped about 2/3 way through the job.   If I had the time (and money) again I would just flat it down and use filler primer to build it up and fill all the tiny cracks.  This was not good value for money and left me no further forward.  If you look on my Else Europa restoration thread there are a couple of photos after the soda blasting.

[Paul_71]

Thanks for the information and advice. My car has already been sprayed in the past in Black (was red) and the quality is bad. Not only is some of the paint flaking in door jam areas, under light assemblies, etc... there are many pimples in the paint. Run your hand over the surface and you get a feel for them. There is evidence of the red under the paint in many areas. However...... I have just sanded back a small area on the side panel and a little confused. There is no red paint, but just a thin layer of black and then goes directly onto a grey dull colour. This is also very thin and actual came through to the FG in a few areas. Is this the Gel Coat? Should it be so thin? Or did the previous guy strip it all back and use a primer - hence why the finish is so bad.
I'm certainly looking to avoid the blaster (although he is a vehicle specialist blaster - not sure if so specialist in Europas!) and invest the time to take the paint back. Just need to know how far to go.

[buzzer]

It is quite possible that the red you are seeing is cellulose stopper which used to be used for very fine filling. The grey is the primer and the "clear" beige colour is the fibreglass clear gel coat. The gel coat is a thin layer of resin finish and will vary in thickness. It can be difficult to judge if you have gone through the gel coat, you should only need to go through the gel coat where it is damaged with cracks or blisters. Cracks need grinding back till the cracks are gone (they can go through to the fibreglass if they are particularly bad but I would not expect a lot of that, only where the body has suffered stress).  Where you have gone through the gel coat there is a old of ways to repair. The conventional way is to use fibreglass tissue and resin to patch over the exposed fibreglass. In some cases as on my car it was whole panel! The other method is to use a special carbon fibre filler which is put on. I've not done this but with the complex shapes on a lot of the Europa it will be difficult to sand back I would expect. I would then suggest to apply a layer of resin filler primer (upol 80 I think) that will seal and prep the body ready for getting a good flat surface for the paint There is some good guides on the net how to redo fibreglass, and also some really bad YouTube videos on repairs, so do some research. The more care you take the better the result usually.

Dave

[EuropaTC]

Your second photo looks to me as if you are at the gel coat level.

On the red paint mystery, it could be that your car has been accident damaged and the panel you've chosen was a repair section. Or it could simply be that the previous respray only took the paint to gel coat on the main panel areas, leaving door shuts and similar recesses around panels in the original paint. This is very likely if the doors weren't removed completely for a respray - something I've certainly done if the paintwork is sound in those areas.

To give you some idea, these two links show the 2011 & 2013 resprays on my car, which is very amateur but might give you some idea of what to look for. The Elan is probably better for your purposes and if you want any higher definition photos just drop me a line.

http://www.martley.plus.com/lotusland2016/europa/16europa08.html
and
http://www.martley.plus.com/lotusland2016/elan/16elan11.html

The first shot of the Elan rear end is basically all gel coat with just traces of the spray filler I used on the previous respray, this is showing up as grey in the photo. The second shows a closer view of gel coat level plus raw matting where I've ground down to make repairs. (I ended up chasing that "crack" right through the panel ! )

Brian

[StrawberryCheesecake]

Spray filler is very hydroscopic, so unless it's painted very quickly after filling, it will need to be thoroughly dried out before painting, to avoid micro blisters in the top coat. That's possibly the source of the pimples you feel in the current paint.

[Rosco5000]

I have to say my dad had his Elan+2 blasted and i think he regretted it.  There was a ton of pin hole filling, it took him a long time and if you are paying a shop to do it that time will add up.  In the end the car still got painted and looks fantastic.  In the end I think there is no magic bullet here, you either spend more time stripping the old paint or you spend time filling pin holes later.