NightshiftHD

A question for DUB and other paint/body experts here.

I am getting the body of my 66 ready to paint. I have already removed all the color (30 yr old lacquer) and am now left with what appears to be 2 layers of primer. The top layer I think is gray epoxy primer and very hard. Its hard to sand and gun wash with Scotchbrite doesn't really touch it. Where I have removed this gray epoxy primer is a creme colored primer on top of the fiberglass. Its also very hard to sand but it does come off (slightly) easier than the gray primer scrubbing with Scothbrite and gun wash.

So the 1st obvious question is "why do you want to remove the primer?" The answer is because I can see (what I call) solvent pops scattered around the body in many places. These "pops" are coming from below the gray epoxy primer so I'm thinking the surface was not properly cleaned prior to priming. I plan to remove everything down to the bare fiberglass to ensure I'm starting with a clean slate so to speak.

What I'm looking for is the best way you professional body guys remove this very hard primer? The best I can come up with is to block sand the gray epoxy off with 180, then with a TON of work remove the remaining creme primer below it with Scotchbrite and gun wash. I'm thinking I should not sand down into the fiberglass and risk raising the strands and then needing to re-gel coat.

Thanks in advance for your advise. Cheers, Bill

DUB

What is this 'gun wash' you are referring to???

What is it made out of????

How much of the car do you have to strip that have the two coats of products you are removing???

I wish I was there to see how long it takes you to successfully strip an area the size of a dollar bill...just as an example.

Some primers are SUPER WICKED to get off...especially if they are catalyzed primers such as polyester primers like 'Featherfill' or 'Slicksand'. These types of polyester primers are activated with MEKP...which is the same chemical that is used to activate polyester fiberglass resin. And I can tell you that primers like this will not even budge if 'Aircraft paint stripper' from Klean Strip is applied to it and allowed to sit for a LONG TIME.

I am concerned about this 'gun wash' you are using....but until I know what it is made out of or what it is...it is your choice to use it. My fear is a unknown solvent that is a part of this 'gun wash' that can possibly migrate into the factory fiberglass.

I can tell you that I am NOT afraid of blocking off primer that is so hard to remove with other methods. I am not a total fan of media blasting due to the mess it creates...and if the primer that is trying to be removed is so hard...when it is coming off the fiberglass...the actual fiberglass panel can then also be damaged due to excessive time in a specific area being blasted.

SO...I would not hesitate to block and hand sand it off and I would NOT fear any possible damage to the factory panels because I am going to apply gel coat to it anyway.

DUB

NightshiftHD

Dub, thanks for the quick reply. I've been out in the shop sanding/washing that deck lid panel for hours. A dollar bill ... it takes me about 5 minutes to do that size down to the bare fiberglass.

Ok, Gunwash is a cleaning solvent we have here in Canada that is used by body shops to clean up spray equipment. Its basically a cheaper (less refined) version of Lacquer Thinner. I've attached the label off the 5 gal can so you can see. It DOES NOT touch fiberglass whatsoever. I've hand sprayed it all through the interior floors to melt the spray contact adhesive St. Louis used to stick the carpets down. And I sprayed/scrubbed the entire underbody to remove tar, paint overspray etc. Engine compartment too. My interior floors and underbody now look prestine!

I think the entire car is covered with these 2 coatings of primer. Now that you mention it, the cream colored primer directly on top of the fiberglass does act like a high build Slicksand. The gunwash with Scotchbrite basically makes it into a slurry after a LOT of scrubbing and when you wipe it off with paper towels, its like a cream colored paste. Because there are "solvent pops" scattered all over the car in various places, I can't trust that proper cleaning was done so I want to take everything off. There is no evidence of the original red oxide primer underneath it all ... at least from the parts I've stripped so far, so whoever painted the car 30 yrs ago stripped it down to bare glass from what I can tell.

I was thinking the top (gray) primer was epoxy, but I guess it could be a polyester primer as well. Nonetheless, it is very hard to remove and like I mentioned, gunwash will not even soften it. Neither will lacquer thinner (I tried that first).

I agree with you not to media blast. Way too messy. I did blast out my tail light pockets (I taped up the painted surface areas first to protect) and it made such a mess I quit.

When you say "because I am going to apply gel coat to it anyway", I'd like to understand this better. If for example my bare panels do not have any fiberglass hair raised to the surface, can I not just prime right on top of this? I'm planning to use epoxy primer and paint B/C. If I need to apply gel coat, what product do you recommend Dub? Really appreciate the council. Cheers, Bill

NightshiftHD

Forgot to ask, I tried blocking with 80 to cut thru the top gray primer and it does go a little quicker. Then I switch and block with 180 to get the cream primer mostly off. Then finish up with Scotchbrite soaked with gunwash.

What grade of sandpaper do you use to cut thru hard primer Dub?

DUB

Thank you for answering my questions.

The 'gun wash' is fine to use. It is like lacquer thinner and what is in it does not raise any concerns from me. I would use it if it was all I had at the time.

AS for the grit of sand paper. I honestly would use 80 grit and not think twice about it. BUT...keep in mind I also know how to block and able to 'read' the panel when I am blocking it so I know where the 'highs and lows' are. And then I will know how to further address any major surface abnormalities by blocking them in a different method. OR...stopping the blocking in that area becasue I know I need to prep that area and fill it with VPA (Vette Panel Adhesive)....due to the low spot is TOO SEVER for me to continue blocking on it ad actually taking off too much fiberglass. So...knowing how to 'read' a panel when you feel it and know if that area needs to be filled in or if it can be blocked a bit more so the gelcoat and fill it in when it is applied.

When the body has been prepped with 80 grit....I will glaze over it with 180 and get a better feel of it and if it is OK...I will apply the gelcoat on top of that. I am NOT so worried that 100% of the body has been perfectly sanded with the 180. I am just knocking down the grit factor of the 80 grit a bit.

And when I write: "How to 'read' a panel. I mean having the ability to fell it with your hand and know if areas are high or low and HOW much they are high or low. You use your hand and not your eyes. Using BOTH your hands and eyes along with a specific light source will come later in the process of getting the body to perfection.

You can apply a primer right on your fiberglass panels. Many people choose a different method than what I do. Applying a polyester primer on the bare glass has been done and works. Applying an epoxy primer and then another primer for building it up so it can be sanded and contoured has also been done. I prefer to apply a gelcoat on fiberglass panels like what your car is made out of. I know the properties of what gelcoat provides will better suit my needs of protecting the fiberglass. Using gelcoat is NOT a cheap way out or substandard product. Actually there is nothing exactly like gelcoat. Gelcoat is in a world all its own. The closest product that may be considered as a substitute is a polyester primer. But a person would have to also be CAUTIOUS when choosing a polyester primer due to they are also NOT all the same. So...testing it and making sure it works well is wise. BOTH products (gelcoat and polyester primer DO require a pant gun with a rather large fluid tip due to these products are so thick and are high build. A regular paint gun will just NOT do the trick in applying these products correctly and effectively.

Bill,

This statement below is NOT directed at you. But I feel now is the time to type it out again so those who may read this...if it applies to them...hopefully they will take it for what it is worth.

Any one who is venturing into doing their own body and paint work.. Take the time to stop and practice. If you feel you are going to win an award on who does their car the cheapest...trust me...there is not trophy given out to those who get it done for super cheap.

SO...obtaining a panel that you can practice on that is of a fairly decent size would be worth it. SO...when you get to your car...you have already ground on the spare hood....did fill work....and purposely left some gouge marks in it here and there. Then apply your choice of gelcoat, primer, sealer paint and clear. DO the entire panel from start to finish. Even sand and buff it.

Why am I offering this advice. Simply so....you can see how well you did your body work. And the deep gouges you purposely left in the panel are there so when you CORRECTLY apply the gelcoat ( if you choose to do so )...or primer and block it. You will know what you can actually fill in BECAUSE you properly applied the gelcoat to its needed mil thickness..and the other primers on that...and so on.

And applying the paint and clear ( if you are doing it all) will also let you be able to know how much clear you actually apply due to also shooting a test panel that will allow you to measure the mil thickness of the clear. And when you sand and buff the panel...you also do a small metal panel so you will see for yourself on how much gelcoat, primer, sealer, basecoat and clearcoat you applied....because when you shoot this metal test panel...you apply the first coat of gelcoat or 'whatever'..then tape off a small section of it to protect it from further coats begin applied...then each layer to keep taping of off so when you are done. ALL of the products you plan on applying on your car are on this panel. And you can also leave some bare steel so when the mil gauge is used...you have a bare steel starting point...and how much you sanded off (because it can be measured)....so you know when you are all done....you are not GUESSING.

DUB

Whatever a person chooses to use...I am not hear to judge that. But whatever you choose to use...do yourself a HUGE FAVOR and see what it does for you. 'Guessing' that it will be OK is NOT the way to do this.

SO...if anyone out who reads this thinks what I just wrote is total B.S. That is fine by me. Then all I can 'say'...I HOPE they do not start a thread due to a problem that occurred in a product they NEVER used before.

DUB

NightshiftHD

DUB, very good advise and thanks for taking the time to spell this out so clearly.

While I was waiting to hear back, I did try blocking with 80 on a section of my deck lid yesterday, and was pleasantly surprised that it really sped up the process of cutting thru that top primer material. Once I got it down to the bottom primer material, I switched to the 180 block to go the rest of the way down to the glass. I was initially shying away from 80 thinking it would leave a lot of sanding scratches, but it really doesn't if you just use it to cut thru the first heavy layer. I certainly don't have the knowledge or feel that you do in order to use 80 all the way down to the glass, but this process will make my work much easier for sure.

On gel coat, do you spray with a 2.0 nozzle or larger? And can you let me know what brand of gel coat you prefer (or is that allowed)? If not, I can PM you for that info. Cheers, Bill

DUB

YES...you will want a larger than 2.0 fluid tip if possible. I would have to double check my gun but I think it is a 2.4 fluid tip.

AS for the gelcoat. I get mine from a fiberglass manufacturer down in South Carolina where I can dive and get it in about 1/2 an hour. He can not ship...I have already asked.

This is some that 'TWINRAY' used.

https://www.corvetteforum.com/forums...f-gelcoat.html

Possibly read this thread also.

https://www.corvetteforum.com/forums...-question.html

Also look at this.

https://www.corvetteforum.com/forums...mendation.html

I TRUST Evercoat products....so even though I do not use the gelcoat that is shown in the thread above...I would use it IF I could not get what I use currently. And YES....I prefer a gelcoat with NO WAX in it and I use the PVA over mine to seal it off from air so it cures as designed.

DUB

NightshiftHD

DUB, thanks again for all your help and advise. Much appreciated.

I have studied all the threads on using Evercoat GelKote. My initial plan was to block & wash off everything on the car now down to bare fiberglass, being careful not to raise any hair, then go straight to epoxy (black) primer. I understand your reasons for starting with a black base to ensure absolutely no shiny spots remain. How does epoxy primer compare with GelKote as a base on bare fiberglass? And if beginning with epoxy is acceptable, is the target thickness still 20 mils finished (after blocking), prior to a seal coat before base/clear? Cheers, Bill

DUB

Due to epoxy primer is obviously not gelcoat....the epoxy primer you choose should be applied as per the manufacturers recommendations. I know the epoxy primers I do use should never be applied that thick.

I am NOT the person who knows all about the SPI epoxy primer. I believe it may allow its film thickness be that thick. But I have never used it so I can not comment about it good or bad.

I DO use epoxy primer on SMC Corvette panels....BUT ....SMC is different that what your Corvette is made out of. They also can not be compared. Which is why I use gelcoat on fiberglass panels like your Corvette has.

You can use on your Corvette whatever you choose. All I will comment on is what I use and how I do it. SO asking me if 'something' is OK to use. If you ask about a product that I do not generally use...you will get a reply stating such. I will not 'tell' you that if a different product is OK to use when it is not what I use in a specific scenario.....and you keep asking and asking...waiting for the answer you want to 'hear'....and then take my comments as 'gospel'...and then it fails...and then I get blasted because I 'said' that is was OK to use.

I know countless people who use epoxy primer...BUT..on fiberglass like what your Corvette has...I do not. That is my choice.

BOTTOM LINE....due to the blistering you have going on...epoxy primer will NOT create a barrier anywhere close to what gelcoat can do. That is not an opinion...but rather a fact.

DUB

NightshiftHD

DUB, on the comments about black base ... I understand from your earlier advise you prefer black gelcoat/primer as that allows you to see any shiny low spots remaining in orange peel better than light gray or white ... so you know the surface is completely dulled and prepared for the next step. So I was just commenting that I understood this concept and will also use a black primer ... or gelcoat too if I go that route first.

Ok, on gelcoat vs starting straight away with primer, I have to absorb what your process is and decide if thats the way for me also. I didn't expect you to comment or advise on things you don't do, or are not experienced with. And even if you did and something went wrong, it would for sure be my fault not yours. And I would never rag on you for giving wrong advise ... but then there are hundreds of other people searching for, and reading these posts and so I understand your caution when providing advise to me or anyone for that matter.

I just want you to know I REALLY appreciate all your advise and guidance and realize it takes a tremendous amount of your time to respond to everyone's questions and you do it for the love of your work and to help us all from making some of the same mistakes you've learned over the years from hands-on experience. Cheers, Bill

DUB

Bill..I am glad to help you if I can. And by no means am I judging anyone who chooses to do it differently than how I do it.

Send me a PM. I will send you my shop phone number so you can call me and we can talk if you want to do that. Unless you want to go back in this 'paint/body' section and look for gelcoat threads.

DUB