alexandervdr

I had my C2 body soda blasted, many cracks that were hidden under bondo and bad repair appeared, I fixed them with fibre and polyester.

The body looks like in the picture, taken before I fixed all the cracks.

My question: the surface of the panels is slightly grainy (because of the blasting), and where I repaired I get perfectly smooth surface. So I tought, why not spread a LIGHT coat of polyester over the whole body and sand it down. Polyester should stick best to the panels and deal with the glass strands that may me tempted to separate from the panels.

I know that most would go for primer instead, but somewhere I feel this would not fix fibres as well. And I am aware too about the shrinking problem, but painting is months out anyway.

Is this the most stupid idea ever?

Dave Tracy

If you have known contour issues, you could use Vette Panel Adhesive. DUB recommends this material. I have tried it and like it. Porchdog, another professional along with DUB, recommends SPI epoxy primer as a sealer and build agent. I'll let others chime in but at least this is a start for you. My '64 is in primer and will be likely painting it this summer.

929nitro

First thing to do is to make sure the body is nuetralized per the paint manufacturer you are going to use. From what I have read some paint manufacturers will not warranty a job done over soda blasting. I know places like SPI will specify how to neutralize soda blasted items for best results. If I recall I have also read where Porchdog talks about epoxy primer locking down fiberglass strands on bare fiberglass.

DUB

I will "jump into this fire".

First off...you have to get the exterior cleaned from the soda blasting and make sure that the panels are COMPLETELY DRY if water is going to be used. I do not "soda blast" panels so I honestly can not tell you the CORRECT method. But I will write this. This cleaning process is the MOST IMPORTANT Step you are going to take at this time. Because if you do not have it clean...how can you expect anything to stick to it....and I am talking on the microscopic level. So...your attention to making sure it is done RIGHT...and maybe doing it again and again will be TIME WELL SPENT and NOT WASTED. I know ..I will clean panels many, many times when I am worried about adhesion that I have to guarantee forever when those panels were subjected to a foreign substance that can ruin EVERYTHING. It may take a few months to dry out...so i hope you are not in a hurry...unless you have a bake booth and can cycle it many times.

I know that if you contact "porchdog" he will recommend his method which is different than mine. That way you can choose what method you care to employ.

I ...myself would NOT cover the entire car in Vette Panel Adhesive and sand it down. NOW...I know it is "grainy" which is normal after that type of blasting. IF you have severe material loss and low spots due to the soda blasting...I would fill it in. If I had bad spots...like I have encountered from other types of media blasting...than I would fill them in if they are severe enough. I know what is and what is not severe so it is hard for me to tell you what to fill and what I would let "ride".

NOW...I myself would gelcoat the entire exterior of the car...and not on any steel pieces...such as the latch area of your doors, door hinges and headlight housings/bezels. Those get epoxy primed due to being steel after proper prepping obviously.

Depending on how severe your fiberglass strands are...the gelcoat will fill in and lock them down and when cured...the gelcoat will prevent any major problems as long as the gelcoat is applied to a minimal thickness of 20 mils after sanding. I have used gelcoat for fiberglass bodied cars for a very long time and have not EVER had a problem. It does take a gun that can shoot it correctly...which most people do not want to invest in. Because this gun can not or should not be used to paint the car due to the needle size is so huge. I have aided many forum members and some of them actually gelcoated their cars. I will tell you like I told them...they need to shoot a test panel and actually see how many coats of gelcoat it takes for them to achieve the 20 mils AFTER sanding. Just going in a pounding on two coats does not mean SQUAT!!!! If you do not apply enough gelcoat...you are just wasting your time. And you have to be...or SHOULD be conscientious about how you are shooting any product so the panels get covered evenly. I watch some people when they are priming just running the gun across it all "*****-nilly " and not treating it with the attention is deserves...and then..."they" wonder why when they sand the primer down they have areas where they sanded back down to the steel or fiberglass...and it has to be re-primed AGAIN.

I would have ALL of the bodywork completed before I gelcoat ...which should be obvious. And for what it is worth...I use ONLY Vette Panel Adhesive for any filling repairs and panel delaminations. Major cracks get fiberglass and resin laminated.

DUB

alexandervdr

I did water clean it many many times, including the use of neutraliser. And I do have time.

The surface is grainy (only lightly) as you say, however when looking close I see very thin and short surface cracks all over. Fibre strands are not loose. These micro cracks where the reason for suggesting covering the body with a light coat of polyester. I believe the purpose is identical to your gelcoat suggestion, and gelcoat may indeed be the better solution. I am repairing all cracks with fibreglass and resin, and do count on filler only to correct for the minor undulations and imperfections.

DUB

I am glad you have the time. Most people do not and get in a rush.

Also...if you have large areas of hand-laid fiberglass and resin..I would highly suggest that you under-cut it a little bit and then finish out the repair in Vette Panel Adhesive. The main reason is that unless you vacuum bag the repair...the chances of micro air bubbles being in your lamination are great...and even though they might be really small...when you go and shoot something in it...they grow like crazy and become really big craters. I always skim coat the VPA on all hand-laid repaired regardless.

Just be careful with these micro-cracks. When I encounter them I often times will take my grinder and lightly grind on them at a slow speed and see if any chunks fly off. If the surface looks like tempered glass when it breaks....you do want to be watchful of it...especially if these crack are on the top surface only and not on the sides....and along any sharp radius or bends in the fiberglass...such as around your taillight panel and bumper area.

Just to clarify... covering the entire surface with a polyester filler is not the same as what gelcoat provides. There are several reasons why gelcoat is used in boat manufacturing and fiberglass parts that are exposed to the elements...and knowing that the gelcoat is what is coming in direct contact with water...it is like a turtle shell and prevents moisture getting into the fiberglass. Polyester filler can not do that. the closest thing to gelcoat that I know of and use is a polyester primer...which is activated with MEKP...just like gelcoat.

Depending if you are going for a factory look or an new and improved version of this classic...I would re-work all bonding seams...if you had not planned on doing it.

DUB

rogman16

Alex--

While I am just a rookie (weekend warrior), I did use a polyester glaze over the entire car... I have a '73 which is SMC which is a different type of fiberglass than what is on your C2... I chemically stripped, glassed seams (and a few other bad spots), filled minor imperfections with VPA, lightly hit the entire body with 80 grit, skim coat of Evercoat's Metal Glaze (most if it was sanded off), 3 iterations of PPG K-36 primer with guide coat and sanding, and then PPG BC/CC...

Looks pretty good for an amateur, and will get my next chance to check it out next month... Almost year since the last shot of clear coat was shot, so anxious to see how everything is holding up... Stationed in Germany and going back to Vegas to pack her up and ship over to Europe...

Here are some pics:











Good luck!!! I know it is a lot of work...

Rogman

Dt86

Nice job man. Looks like glass!

alexandervdr

Thanks Bud for your clear instruction.

I am indeed concerned that just putting polyester filler is not dealing with the base panel imperfections in a sufficient manner.

Some questions, from a less than experienced guy

what is VPA?

you refer to a polyester primer as the closest thing to gelcoat: would you recommend a brand/type?

You suggest to re-work the bonding seams, I assume you refer to the lines on the the picture below? How would you 're-work' them?

alexandervdr

cars looks stunning! Gives me the courage to keep going, it's indeed a lot of work.

What brand of polyester glaze did you use? And same question as for Bud:when glassing the seams, do yo first 'valley' them out some mm with a grinder to then glass/polyester them again?

rogman16

Appreciate it...

Been a long time since I've worked on a C2... Here's a picture of the grinds on my C3...



I used Evercoat's Metal Glaze for the polyester skim coat... Here are links to it and to VPA...

Metal Glaze

VPA

Rogman

DUB

When I do seams ...they look pretty much like what is pictured in the above post from, "rogman". Grind down and out, then taper the edges wider than what was original. In most cases I do not grind down all the way in the center of the seam to see the bonding strip...but that is also subjective due to each car is different and sometimes I have a car that actually has air gaps in the bonding seam area and grinding down to the seam is needed. Some Corvettes may have a lot of adhesive between the bonding seam and panel..others do not...so when prepping the seams...do not "freak-out" if you do see the bonding strip....the main thing is not to grind the bonding strip too much.

Then I apply the Vette Panel Adhesive (VPA) in the seam and shape accordingly.

I will be more than glad if you want to call me and I can give you a quick tutorial on using the VPA. This stuff gets hard...and if you wna to sue it on yoru own and learn...fine by me....nobody ver gave me any tipos on using it....but teh offer still stands. if you wan to know some tricks...call me...beacue I can not tpye for hours on this matter...a phone cll gets it done quite quickly.

(704)394-5150 EST
M-F 8-5
Sat-Sun 10-4
If you get my answering machine...leave your name and number CLEARLY...and I will call you back.

DUB

alexandervdr

To Rogman and Dub,

Tnx for the help.

How do you do the grinding of the panel seams?

You fill that with VPA only? No glass matt?

To dub: I live in Belgium/Europe, not very practical for a call, but when I get stuck ...

rogman16

Alex--

I used a 3 or 3.5" flapper disk to do the first half of the grinding out, and then moved to 80 grit by hand on a 1.25" round dura block (AF4404)...

http://dura-block.com/sanding-blocks/

Was a lot of work and mess... As long as the sandpaper stayed pretty fresh and clean, it really didn't take that long... Wear PPE!!!

I filled in with resin and glass...




I then used VPA and the Glaze as my final two steps before primer...

Rogman