A Few Beginner Questions

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PUNISHER VETTE

1. I'm blocking the firewall on my vette and it seems the epoxy primer is gumming up my sandpaper almost instantly. It's 180g paper.
Is it normal? and I just need to accept it?
Is my paper being the Duragold kind a cheap variety and as a result this is what I get?
I sanded some that had sat for a week or two, and this firewall sat for 24hrs.. Both have done the same thing so I don't think it's a curing question. Maybe the epoxy being a 1:1 needed to be reduced or something I am unaware of?
Once I get through the top layer of epoxy it gets a little better...but still doesn't seem right to me. I'm using compressed air very often but sometimes it can't get the darker chunks off very easy.



2. I plan on spraying the engine bay body color(a cyber gray metallic). Mostly because I want my vette to be more unique than the plain Jane black most do. But I also want as much practice spraying metallics as I can before attempting the outside. Knowing you have to get the outside perfectly smooth before spraying I'm wondering how perfect does the firewall really need to be to not look like crap?
Being a corvette it has imperfections galore in this area and I'm not really wanting to spend the 100+ hours blocking it would need to get it perfect. Anyone have any pictures of what an unblocked metallic paint job looked like? or a scratch not fixed and painted anyway? Cyber Gray is a darker color so I'm hoping that helps in terms of blending in some?



3. Should the epoxy lay down mirror like or is what I have about normal? Didn't know if I needed to adjust my gun settings differently to get it to spray smother?



Hopefully these aren't too dumb a questions lol. I'm sure I'll come up with ones even dumberer as I keep moving forward.
 
i wet sand everything. i use gray epoxy so i cant help here.
one thing to remember when dry sanding. the faster you sand the more heat you create. heat causes clogging much of the time.
 
PUNISHER VETTE;40278 said:
Yes.
Click to expand...
OK, do you know what the surface temps have been over the week of curing? When epoxy gets close to its minimum cure temp, it gets kind of "lazy" and takes a lot longer to cure, especially if a lot has been put on and solvents might still be trying to escape.
 
The 1/4 panel I sanded after a week of curing was plenty warm. In the 70s often. The firewall I let cure for only 20hrs was on the edge of its limits. 65ish. So it might explain the firewall but doesn't for the fender. Since they both felt the same I'm not too sure it was temp related. But I could be wrong.


I've never wet sanded anything before...guess I can look up how to do that and give it a shot and see if it's any better. Any insider tips I should know that I won't find just googling wet sanding?

Thanks!
 
When it is cured it will powder nicely. What you are seeing is partial cure, though the glossy skin will almost always ball up a tiny bit when the material is less than a few weeks old.

I think you need more heat, more cure time, and maybe fewer or less heavy coats. We have to face the fact that high quality automotive epoxy is a slow curing beast.
 
I sometimes rub the sandpaper down with a red scotchbrite pad to remove some of the build up. Also helps keep the shop cleaner vs using the air.
 
Yeah. All things I can try. The 1/4 panel was 2 coats. The firewall I did 3 just due to the amount I had mixed up. I could probably do 1 or 2 lighter coats. But I'm afraid heat is going to be tough from here on out. I heated my garage to 70 for the firewall for that 20hrs. But no way I'll heat for multiple days to cure lol.

I'll see if the rest of the firewall sand any different after curing for more days.
 
Keep in mind that below about 60F, the curing process just about stops.

My shop gets heated 24/7, not just for epoxy but for all the other things I usually have curing in there. It's expensive, but necessary.
 
Yeah. If it stays cold I guess I'll have to start heating more and being more selective when I sand stuff.


So what are everyones feelings on having to get the firewall perfect for a metallic paint? I completely understand the outside needs to be and rightfully so. But with all the stuff getting bolted to the firewall and in a dark engine bay will it look decent if I have a few nicks and imperfections in spots? Like in the photos the tiny chips?
 
For glossy firewalls I settle for smooth, but not necessarily perfectly straight. I would not leave nicks and gouges, but I would not float out every wave with putty either. But that is just my own personal preference. Once it is sanded, you can wet it down with solvent based wax & grease remover, its gloss will help you see if you can be happy with how you have it at that point if you were to spray it.
 
Personally, I try and get the firewall perfect because its preliminary to the rest of the project. If you consider it "practice", see how good you can get it as a learning experience. When I paint epoxy, I have four pieces of conduit hanging from the ceiling. After I paint, I hang four 10'x8' tarps from the ceiling, clamp the corners together and put the project inside with a heater and a shop light. It cures the epoxy at 90 degrees easy. Thats surface tempreture of the metal, not booth tempreture. My epoxy dry sands great after 24 hours. This way the cost of maintaining the heat is reduced to a minimum opposed to heating the entire shop which is on a thermostat to never drop below 45 degrees here in Northwest Montana.

I heat my paint booth to 80 Degrees to shoot, let tack, then roll into the mini tarped heat booth and crank up the heat inside the tarped area. So far has worked awesome for me. Conduit was $6 per 10' stick (4), tarps were $14 each (4), and curtain hooks were maybe $5. I used five spring clamps per corner to clip the corners together after the project goes inside and the heat source is turned on.
 
You're probably right in that I need to take this part seriously if I intend for it to be "practice". I'm going to do my best but I'm not going to obsess as much as I will be doing on the outside. I'd say 90% ish :)

The firewall sanded much easier after having sat a week. So it must have been mostly not enough cure time... I'll make sure I heat better and look into creating a heating tent of some sort so I don't have to heat my whole garage for a day or two. Amazing how many low spots and areas that you don't really see show up till you start blocking.

Sanding #1 almost done...

 
Crash is 100% dead on... If you are gumming the paper, the epoxy isnt cured. Either because of temperature, how it was mixed(did you observe the induction time?), or the application being way way too heavy. The SPI epoxy(unlike many others) sands very well. Even dry, atleast on an orbital.

That said, myself personally I use the epoxy as a good foundation. I spray it with my good gun so it lays out nice. Then from there, I do the filler work and switch to 2K primer to get everything baby butt smooth. Only time I sand epoxy is if it sat too long, or I got imperfections in it. 2K sands so much easier, fills 100X better and is ready to sand in 30 minutes. While I accept 2K does have shrinkage compared to epoxy, if you arent asking it to fill the 40 grit gouges its advertised to do, it still performs very well. I suspect that most beginners who are still trying to figure out what "smooth" really is, will end up with a better job where the final prime is done with 2K over the laborious process of sanding several coats of epoxy.

Punisher, give this a shot. I saw in another thread your local dealer is PPG. Get a nice couple coats of epoxy on there, then try some Shopline JP202 2K primer over that. If all they sell is PPG they should be a Platinum dealer and sell shopline. If not they sell Omni. Just ask them for the equivalent. Should run you about 115$ for a gallon of primer and quart of activator. Shoot with a 1.8 tip or so, its thicker than epoxy. I usally add a few oz of reducer to it to thin it down a little, its pretty thick. But you get that to spray nice and smooth, when you go to sand its going to powder immediately. Start sanding with nothing rougher than 220. Once thats nice and all the peel is knocked off, go to 320, then 600 for the color you want. Then seal it and shoot the color
 
BoostedOne;40563 said:
Crash is 100% dead on... If you are gumming the paper, the epoxy isnt cured. Either because of temperature, how it was mixed(did you observe the induction time?), or the application being way way too heavy. The SPI epoxy(unlike many others) sands very well. Even dry, atleast on an orbital.

That said, myself personally I use the epoxy as a good foundation. I spray it with my good gun so it lays out nice. Then from there, I do the filler work and switch to 2K primer to get everything baby butt smooth. Only time I sand epoxy is if it sat too long, or I got imperfections in it. 2K sands so much easier, fills 100X better and is ready to sand in 30 minutes. While I accept 2K does have shrinkage compared to epoxy, if you arent asking it to fill the 40 grit gouges its advertised to do, it still performs very well. I suspect that most beginners who are still trying to figure out what "smooth" really is, will end up with a better job where the final prime is done with 2K over the laborious process of sanding several coats of epoxy.

Punisher, give this a shot. I saw in another thread your local dealer is PPG. Get a nice couple coats of epoxy on there, then try some Shopline JP202 2K primer over that. If all they sell is PPG they should be a Platinum dealer and sell shopline. If not they sell Omni. Just ask them for the equivalent. Should run you about 115$ for a gallon of primer and quart of activator. Shoot with a 1.8 tip or so, its thicker than epoxy. I usally add a few oz of reducer to it to thin it down a little, its pretty thick. But you get that to spray nice and smooth, when you go to sand its going to powder immediately. Start sanding with nothing rougher than 220. Once thats nice and all the peel is knocked off, go to 320, then 600 for the color you want. Then seal it and shoot the color
Click to expand...

Wow. Thanks for the advice!
Yeah. the epoxy cured WAY better waiting a few more days. And I just got done spraying a 2nd few coats the other day that I put a tiny electric heater in my makeshift heat tent. Plastic around the whole car. It heated the car for 24hrs at about 75-78 degrees. Worked pretty good but I have improvements for next time to get it even hotter.



I've been tossing around the 2k stuff over and over and just can't make a decision. When does the 2k have shrinkage? Because I don't wait long enough between coats? Or just too thick in spots and it can't handle that?

I really do think I could benefit from using it.. i just don't want to use it and get more issues because of my learning curve.

Why go to Colours and buy their 2k? Just because they're local and quick? Cheaper than SPI? dare I say better? lol.

Although I haven't researched it too much I noticed SPI has a few 2ks. turbo, high build, normal... Wonder what kind I would need(my guess is high build?) If I call they have it shipped to me in 2 days usually. Although it's full of packing peanuts!!!!
 
What is PPG's good brand?

I see they sell a few different products and want to make sure I get the right one.

If I go to the Colours store and tell them a stock GM color will they be able to look it up and make it for me? Or should I bring them the code for it?

For a first paint job should I get more than I think i'll need to be safe? I have the corvette, engine bay, old hood, and maybe my scooter I'm going to paint. 2 gallons should be plenty right?

The tack cloths... That's just between coats right?
 
Sorry I didnt see the response:cower:

Shrinkage on the 2K? Honestly I'm not sure.. I've never experienced it myself, atleast not that I know of, haha. I was hoping someone else would respond. But I think it is usually a result of just having way to many mil's on there.

Regarding how it works compared to the SPI 2K, I also cannot answer that. I tend to experiment with different things only when I am trying to get better products. I came to SPI for clear because of Rusty, a long time ago he was using it. In 2006 or 2007 I bought some Nason for a cheap project and somewhere along the line i bought some shopline clear, but for the most part the only clear I have bought in years has been SPI.. I had all but written off using Epoxy after some bad experiences with other brands that cure hard as a brick. Tried SPI's now its part of any job.
However, just as SPI has its products that I won't substitute(unless I am caught with my pants down and need it immediately), thats how the Shopline 202 is for me and 2K. I used Nason's 2K, and in my opinion I liked it 95% as well as the Shopline, but still not as much as the shopline.

Regarding the Turbo, high build, standard. If I recall correctly, the JP202 I use is not considered a high build. It is more than adequate. I am actually wary of the "high builds" because I worry that they are too thick, and would lead to the shrinkage problems I have heard about but never had.

Not saying its the "best" way, but my limited formal training(and what I got was pretty outdated), is I will do the metal/filler work, and usually sand up to 80 on bare metal or 220 on filler with the orbital. At that point theres not much deep stuff for the primer to fill. From there(assuming no epoxy to do), I do the 2K and sand it all with 220 on the orbital, then 320. If i break through I put on another coat so its even and sand with 320. Depending on the color I will do it with 600 on the orbital. If I recall right you were going to do some kind of metallic, so I would go to 600...

Whats PPG's good brand for what? Paint? Their good basecoat is called DBC. Don't get your metallic in Shopline or Omni competing low end lines(although they are ok for solids)... Also I know theres a guy who sells "DBC" online at ridiculously cheap prices. I have used him a few times and was happy, but after a friend of mine had skepticism, I have become too.. The DBC I buy from my platinum deal just smells different... Typically the DBC I get locally smells more foul, like armpit stench of someone who eats alot of onions.. Their shopline doesn't smell that way, and neither does the DBC I bought on line 60% cheaper than my local dealer. I could be totally wrong, but I'm not chancing it anymore...

When you go buy the base coat you need to give them the code and the year. Then they will typically confirm "Ok this is a blue" or something...
 
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