What is the general rule of thumb in a 2K hi-build primers as far as # of coats and block sanding? I recently sprayed 2 wet coats....cured...then blocked with 220 grit. I am going to coat again 1-2 coats and cure. Is it necessary to sand between coats? The final sanding should be what grit before paint? In addition, do you all recommend a primer sealer? Thanks
I normally spray 3 coats of primer at a time, but it all depends on how thick you spray it as to how many coats you want to put. You only need to sand between coats if you spray outside of the drying window. I usually block my first round of primer with 180 grit, reprime, and then block with 320. Wetsand with 600 if you plan on spraying a base/clear solid color. Sand with 800 grit wet if you plan on spraying metallics
I would recomend you find the tech sheets on the product you are spraying, they have a lot of good info. Just search the product online All paint companys have these listed on their web sites. I generally use sealer over 400 for solids and dark colors 500 for sealed light colored metalics,600-800 for non sealed base clear
Do yourself a favor and let that high-build primer cure, the longer the better. I just finished the bodywork on my current project and the car is currently in high-build primer. I have managed the project so that I can now do the wiring, fire the engine, etc.. which will give the primer monhs to shrink down. You don't want to do all of that prep work and then have the primer shrink under your finish coat.
Sorry for bringing up a old thread. When you say block with 320 then wetsand with 600 are you repriming between the 320 and 600 ? Trying my 3rd at home paint with base clear ,yellow with gold pearl. Thanks.
i would bet he primed between. if i have a heavily pitted, deep sand scratches or wavy panels i will do the two sanding steps. 3 coats of filler primer over a coat of epoxy, block sand that dry with 180 or 220 , re prime 2-3+ coats depending on how much sanding i had to do to get it straight and smooth. wet sand, as mentioned 400-600 depending on paint type. i like to give at least a week of dry time between steps.
Rather than start a new thread I figured I’d add a question to this one. I have done 2 rounds of featherfill with guidecoat and have my truck blocked to 180. Panels line up nice, no low spots. Planning to spray Uro-Fill 2K primer and block 400 then 500, then have buddy do sealer and metallic base/clear. Question is should I take the doors and fenders off for final prime and block them separately so I can get entire doors/jambs prepped for paint OR leave the truck assembled and just spray the outer skin, blocksand, then take it all apart after and spray the rest? The second option seems it’d be way more masking off but should I be concerned about the panel edges not matching up after being blocked separately? ....or should I not be concerned because I’m basically just taking the guidecoat off and things should line up fine again after reassembly? Do I worry too much? Any advice appreciated. First time I’ve done a full paint job.
Sounds like you have the primer ready, pull the doors and fenders off, seal it all. I normally paint jams first before anything then shoot the body at the same time. You dont risk the damage to anything doing it fully disassembled, just have to be careful doing re assembly. But the finished product shows up 100 times better. I have known guys who Jam out a car together, then shoot the final coat on the outside and it never quite looks right with a door open. Most of those who do it that way are the ones who leave it assembled for the full process. Note, in certain kind of candys or pearls its better to paint the car together for the way the metalflake is sprayed and lays down. In this case I would pull the fenders and doors, jam it first but dont clear, then shoot the body, finally clear starting in the jams first.
like said above, take it apart, seal, sand and paint all the edges and insides, then assemble, align, prep and paint the outside together. lot's of ideas and examples in this thread: https://www.jalopyjournal.com/forum...nt-that-fixtures-and-taping-technics.1008403/
what color and car? Some are easier than others assembling painted. If it’s a solid color you can paint it all apart I don’t recommend painting pearls and metallics unassembled
Whoa! Thanks for all the replies and valuable info. Sorry for not checking back sooner. I ended up disassembling the truck (1964 c10) for final prime and block sanding. You guys mention sealing it and painting it, but I only had it to 180grit with feather fill poly primer. Would you seal over poly primer? My paint guy said 2K first? I ended up taking it apart for the Uro-Fill (which went on very textured) and am now blocking panels separately. Hopefully everything lines up after. The 2K has been a bastard. I don’t know if I’m too cheap and putting it on thinner than required but I burned through it to my poly primer a few times. Starting with 320 to cut the orange peel- 400- 500. Guide coat charcoal powder each time. I’m using activated charcoal from a health store and an old sock. If this is a bad idea please let me know. I’m using a brand new cheap Vaper 1.8 for the 2K and it is going on rougher than the poly. Again, thanks for all the info. First time doing this and stressed right out about it. I plan to paint the truck Turquoise Poly (metallic) Chevy paint code 510. If anyone can recommend an ISO- free finish primer that I can use instead of this toxic Uro-Fill please do. Thanks!
First of all you are essentially using two products that are designed to do the same thing but with different chemical make up. There is no reason to spray Uro-Fill over Feather Fill. Second have you read the tech sheets on either product? I am guessing not if you are finishing your Feather Fill in 180 when the tech sheet calls for finishing Feather Fill in 400-600 grit. Finish the Feather Fill in the proper grit, making sure you have no burn through. If you do spray more and sand more. Then get an epoxy sealer to spray over it. If you do it properly there should be no need to sand the sealer unless you bypass the recoat window then it will need to be scuffed. If you can't spray your sealer without having to sand it you are going to have a hell of a time with your top coat.
thanks for the reply K13. I have actually read the TDS sheets for both products and you’re right I didn’t fully follow the instructions for FF. I’m still learning here and after speaking with the guy that will eventually seal/paint my truck and doing some research on this forum and others it seemed the general consensus is that it is good practice to use high build polyester primer (sprayable filler) to fill in minor low spots and imperfections sanded to 180/220 and then proceed with a 2K polyurethane that sands easier with finer grits, lays smoother, has more corrosion protection and is wetsandable. I was told not to wetsand polyester primer because it’s porous. Again, I’m learning and could definitely be wrong here. There’s obviously 2 schools of thought on this. I thought Uro-Fill was a good choice but it wasn’t or I simply don’t know how to spray it successfully. I am hoping to move forward with a primer/surfacer that is ISO-free.
Epoxy primers do not contain isocyanates, but you still need to use a respirator to spray them. That said, a lot of automotive epoxy primers sand about like concrete and don't have much build thickness. SPI's epoxy is a high build product and it sands pretty good. Not as easily as some of the 2K primers, but not particularly difficult like some of the other epoxies. Don't know whether its available in Canada or not.
Hey metlmuncher I actually used SPI epoxy onto the bare metal prior to bodywork and highbuild. I agree it is nice stuff and sands decent, but doesn’t have the fill/build that I’m after. Just read about an iso free 2K primer/surfacer by Transtar called 2K Kwik Prime that I may try, or a waterborne 1K.
Why do you need something else that builds you have that in the Feather Fill? Block it out properly then spray an epoxy over top. No need to wet sand the Feather Fill to get it to 600. You have an epoxy down already so you are covered for corrosion protection. You are making this more complicated than it needs to be. All these different products are a recipe for disaster for an inexperienced painter. Don't want to come off as a jerk but if you try another primer you will have at least 5 different primers on before you even get to the top coat. That is not a good plan for success. Where are you in Canada?
Sorry I shouldn’t say I need something that builds I just need a primer that will fill the 180 scratches. I should mention that although the Urofill sprayed like crap and left a texture, it does sand very easily with 400 grit. I did not find the featherfill nearly as nice to sand....and aside from a couple burn through spots that I will hit later with epoxy, I think the urofill will be blockable wetsanding to 500. So I’m not looking at another product to spray over top of the Uro-fill. I would like to find an iso-free primer that I can use on the rest of the truck that won’t potentially kill me, I felt like shit after spraying that stuff and won’t be using ISO’s again. Although I have an epoxy under the feathefill I still don’t like wetsanding it. I don’t like the idea of it sucking up water.
I have done auto body and paint for a living for over 30 years . All primers I have ever used will fill 180 grit sand scratches usually a minimum 3 decent coats is recommended . Try if you can to minimimize heavy texture as it only works against you on your final prep. Always guidecoat . I am a big wet sander for final prep ,a few drops of sunlight dish soap help with the proper wetting of the panels and work wonders for carrying away contaminants . Some sort of squeegee is helpful to check your work a CLEAN rag in your wet sand bucket is helpful for wringing out when finished on a panel to do a final wipe and clean of that panel . I find if you let the panel just hang wet and dry on its own you can sometimes see streaks hanging down in your final finish. Also when you break a car down for final paint a good trick to keep all your nice gaps is to make fine hidden little marks around the bolt heads on the panels those bolts hold down ,this works on fenders, trunks ,doors etc. That way when you put it back together and line these marks back up everything should Fit hunky dory .
I just joined this site and recently started doing a lil body work but I haven't done it in years. When I was 17 I owned a 68 charger 383 4 spd and with the technology today I wish I kept that car. But sadly that story is for another day. But I am looking to get another old mopar to redo. But I have done some jobs without using 2k primer I guess that maybe I was lucky and the body panels were just mostly repairs nothing major. But now I'm fixing a rear quarter on a friends 07 mustang that rotted below the gas door. I did fill the rotted section in with bondo hair after getting the rust out. I using fiberglass cloth on the inside after I got it all cleaned it wasnt big maybe 3 inches long by 1 in tall. But I did block sand a primer it and got it smoothed out. It doesn't have any scratches hardly at all. I'm getting ready to spray Omni 2k primer on it. Would I be right to mix it 4/1/1? Being the body is nice and straight where I fixed it I just want to make sure if you guys think I'm going the right path? Now it is black and I am using Omni plus basecoat and clear on it. I appreciate any input you might have. Thanks
I realize this is an old post but that's where I'm at right now... High build has been drying/shrinking for weeks/months... Question : Do I have to "re-activate" the high build with a coat of high-build sealer before applying base coat? (PPG K36 tinted high-build guide coat sanded to 500 grit over DP401 primer).
Here is the tech sheet https://images.oreillyauto.com/part...ma+acrylic+urethane+primer+surfacer+07+16.pdf do you have to seal it? No. would I seal it, probably yes. It’s hard to beat ppg epoxy Ifs it’s been sanded for a while I’d recommend sanding again.
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