joseph p

If the sparkle of fiberglass threads is showing after years of sitting stripped of paint in all different inside and outside conditions, will spray gelcoat remedy this? There are sections where multiple veins of cracks (like on the topmost part of the rear fenders) are very evident. Do these need to be v'd out and filled? Or will a good coat of gelcoat or filler/primer be all that's needed?
Or is this all past hope?
Thanks

rponfick

A good epoxy primer, such as PPG DP series, will do a good job of sealing in the errant fibers. Nobody uses gelcoat any more except the aftermarket replacement panel makers, and then mostly as a release agent from the molds.

If you see cracks, they need to be repaired. The cracks sound like they are in the bond seams. Grind them down and lay 3 layers of glass over the seam. I am doing the same thing now on a '66 that has sat bare for about 15 years. Not the best way to store fiberglass.
Good luck.
Ralph.

John McGraw

There are still a lot of us who still use Gelcoat and think that it is the best product there is on top of bare glass and repairs. If the cracks you are talking about, are tiny little carcks that run in all different directions, they are spiderweb cracks, and will be pretty effectively consolidated by the use of gelcoat. If the cracks are running in a single direction, they probably need to be ground out and glassed up. There are many who just use a high-build polyester primer surfacer and skip the gelcoat, and they get very good results, but I am a big believer in gelcoat befrore any primer surfacer. Ask the experts at technical support at PPG, and they will specify a gelcoat over all bare glass. It is not an absolute necessity, but it will resolve a host of problems that no other product will.

Regards, John McGraw

TheMongoose

polyester priimer works like a gelcoat and will cover strands well. give it a try. easy to work with too. that's what i used on mine.

Cmacsvette

with John............................

Also Joseph p, just a tip, if you do GC, besure and cure it out good with heat. You can use the sun or create your own. BTW, Corvette Image does not recommend epoxy primer on their PM panels. I'm speaking after market PM glass here, just in case you do use some.
Craig

Corvette Image.............Quote" Please DO NOT use urethane and epoxy primers on REPRODUCTION bare glass parts. The pores and fibers in the laminate will absorb the heavy solvents in those products and will migrate out later to cause blisters." Quote

Also just a note to all, I'll be seeing Jerry the owner of Corvette Image this weekend. If there is anything you would like me to pass on or ask him, I will be more then happy to do it for you. e mail me if you want.

TheMongoose

That's why the polyester primer works as a GC because it doesn't have the solvents in it. Takes a good 3 days to dry hard. gotta sand it in the 1st 2-3 days.

scotty67

I thought products like SlickSand etc, polyester based filler primers with lots of inert powdery fillers were not recommended on aftermarket panels due to their porosity. They just don't seal well.

What Polyester primer product are you having good success with?

Thanks,
Scott

MORHPPLZ

Anybody use a product called Vette fill, not sure of the spelling? Read about it in a magazine once, supposed to be a pinhole sealer and primer. Couldnt find anything on Google.

my58

While we are on the subject of gel coat can someone tell me if rolling or brushing it on is really done and is this an ok route for me to take?

I have read an article in the NCRS Corvette restorer called Re-Gel Coating a Corvette by Joe Vaverka that explains Gel coating and describes roll and brush on methods.

Also is it advisable to gel coat inside the engine compartment and underneath the body also?

I am figuring if it is needed it would be best to gel coat, prime and paint the engine compartment and underside after numerous test fittings but prior to installing the jig fit front back on the car, and then gel coating the outside after everything else is bonded together and re-installed on the car.

Thanks for all thoughts and ideas.

mrichard

All Polyester primers contain between 4.0 and 4.6 pounds of VOC solvents per gallon. This includes products like Evercoat SlickSand and PPG K36. This will not seal bare fiberglass long term and niether will Epoxy primer, period. I am amazed at the advise that is handed out by people with no technical background on various subjects. If you don't know the facts, keep quite until some one who does chimes in that does. No dis-respect, but people are counting on solid advise...

Cmacsvette

Yes, it could be done, but things I personally would be thinking about is, if one is doing a large area and was brushing/rolling, one had better work fast, so the GC didn't kick on em. When it starts to gel......there's no slowing it down!(GC can react strange too if mixing ratios are to low or to high) GC does not like to be sanded, even though you have too.(for a top coat) So now I'm thinking, how do I get rid of the brush marks or high edges where I plan to top coat, more sanding! Anyway, some food for thought, at least the way I see it.

Just my thoughts on engine area and under, I would not GC,only because its so much post prep (sanding) on it for top coat. I did do my fire wall for a little more durability. Just my personal preference, but I like to do primer and top coat in engine area after clip is bonded. I find you still have so much man handling going on during an install, not to mention, adhesive etc, getting in your nice finished area. My 2.7 cents.
Craig

Cmacsvette

--------------------------------------------------------------------------------

"All Polyester primers contain between 4.0 and 4.6 pounds of VOC solvents per gallon. This includes products like Evercoat SlickSand and PPG K36. This will not seal bare fiberglass long term and niether will Epoxy primer."

mrichard,

You sound like a gentleman in the know, my question is. Is there "any" other product out there for sealing fiberglass for a longer term, besides gelcoat? Thankyou.
Craig

Mr D.

How hard is Gelcoat to sand?

I guess what I'm asking is, if I spray My 65 with Gelcoat how long should it take to sand to ready for primer?

Hand or Air???

mrichard

Nothing works as well as Eckler’s or Fiberglast Gel Coat to efficiently seal fiberglass. You probably already know this, but you should use the type that has a paraffin wax that blooms to the surface during curing. This protects the Gel Coat mixture and makes it properly cure. Without it, the stuff won’t always harden. You also must have a good film build to make it harden, usually about four or five coats for us. I like the Eckler's material because it has the wax already mixed in. You just add MEK hardener and spray. The Fiberglast material needs to have their 5% mixture of paraffin and styrene added to it. Both products sand easily with 80 grit paper on a DA sander or by hand. A real benefit of using Gel Coat is that you can do most of your body straightening by simply block sanding it. The Gel Coat material is quite thick, and will restore fender peaks and body lines to perfection, using well known block sanding techniques. We like to use Hutchins Model 4932 VA/DF which is a DA board rather than the straight line motion models some prefer. It has the vacuum assist feature and sucks up most of the black dust when connected to a shop vac. The 4932 Hutchins works well on most of the C2 body and gets it as straight as glass. We don’t try to cut Gel Coat with anything finer than 80 grit papers, because it doesn’t block nearly as straight. As you know, you must maintain a good Gel Coat thickness prior to applying PPG or other your favorite brand of epoxy primer, otherwise the solvents will penetrate the glass and ruin your bodywork. As you know, you can’t sand it all off and expect it to seal. Another benefit of Gel Coat is that it acts like a shell over the bonding seams and prevents them from showing through the paint even though the bonding material expands and contracts at different rate than the base fiberglass material. A final word, most of you probably know that Gel Coat doesn’t stick to anything except perfectly clean bare fiberglass or body filler, assuming you have read the instructions that come with the products.

John McGraw

Mike is exactly right! There is nothing out there that seals fiberglass better than Gelcoat. If you do not believe this, just try stripping a car that has had SlickSand or one of the other polyester primer/surfacers used on it. You will find that the stripper will attack and remove the material. It will not remove the gelcoat! This should tell you a lot about the merits of using a polyester primer/surfacer as an effective sealer on bare glass. There is way too much inert material in primer/surfacers For them to be as effective as gelcoat. They are both polyester resin, but the gelcoat is only resin and a little wax, while the primer/surfacer is more akin to a sponge, with all the inert material in it. This material is there to aid sanding, just like body filler. These primer/surfacers can truly be viewed as sprayable body filler. The gelcoat forms a hard, dense layer, that resists solvent penetration better than anything I have ever used, and I will continue to use it, even though it adds a considerable ammount of work to a paint job. It is hard to sand, and the wax will clog a lot of sandpaper before it is all gone, but it is worth the additional work in my opinion. There are many fine paint jobs that did not use gelcoat, but I do not like to take chances with this much work. How many times have you heard about blisters coming up after a couple of months on new paint jobs that had a lot of body work? I would rather not take chances, and use products that are proven to prevent these kinds of problems. I know that both PPG and Silkens reccomend the use of gelcoat on any bare fiberglass Corvette body.

I use SilckSand and PPG NCP271 as primer surfacers, but I only use them after I have sealed the body with Ecklers gelcoat. I do not try and straighten the panels with the gelcoat, but instead use the primer surfacer to provide that function. I will shoot about 3 coats of gelcoat, and then only sand it enough to remove the wax layer. After that, I will apply the primer/surfacer and block the panels as necessary.

Regards, John McGraw

PierreOlivier

John,

What grit sandpaper did you use? I would presume wet. I am doing a lot of body work and some areas already have the thread issue. I am also putting on aftermarket quarter panels - should I strip the paint off of them after they are on the car?

Pierre

61Rat

This may sound crazy but... have any of you folks who have experience using gelcoat ever tried to blast the wax layer off? I'm thinking that a mild abrasive under reduced pressure might be enough to remove the wax but still leave most of the gel on and provide a nice surfce to start the blocking and priming stage. Any thoughts on this?

John McGraw

Pierre,

I use 80 grit wet. It tends to clog less than dry paper does. I would remove ALL paint and primer down to the bare 'glass prior to using gelcoat.

61 Rat,
I sure would not want to try this. I don't think you could control it well enough. It is not that bad sanding the wax off, and can be done in a few hours.


Regards, John McGraw

GregP

Not claiming to be the expert, but the cars originally didn't have gel coat and the paint on most held up just fine. Gel coat is NOT impervious to liquids, but is actually quite porus. Just ask anyone who keeps a boat in the water about osmotic blisters. You prevent them with a good epoxy barrier coat, not more gelcoat.

Also, you need special mild strippers to NOT remove the gelcoat/resin from fiberglass. Jabsco (my favorite for metal cars) will leach the resin right out of the fibers.

-Greg

Scott Marzahl

After Gel Coat is applied, is it acceptible to still use filler over top of it prior to priming or should one sand through the Gel Coat, apply filler and then re-coat?

Thanks,
Scott