Epoxy Primer Question
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Laughing Gas
Joined: Feb 2006
Posts: 892
Likes: 85
From: Western Massachusetts
Epoxy Primer Question
Bodywork continues. My SOP has been to strip each piece to bare metal, treat any surface rust with Eastwood Fast Etch, then spray two coats of epoxy primer before doing any bodywork. I've been using epoxy primer from Summit and Eastwood. Before applying filler I scuff up the surface. When sanding the filler the sand paper gums up with little nubs from the primer as I sand to feather the edge. Causes the paper to be short lived. Is this normal? It wastes good sand paper. I sprayed these door 6 days ago outside. Temps that day were over 65. Today I filled some low spots and small dents. I've had this issue from the start last summer.
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Laughing Gas
Joined: Feb 2006
Posts: 892
Likes: 85
From: Western Massachusetts
Ebear I agree that it acts like it hasn't fully hardened. Wonder if over catalyzing the mixture might help to speed up the cure. I read elsewhere that SPI brand epoxy doesn't do this. SPI products always seem to be well reviewed. Sounds like it is worth the extra cost. Regarding the Fast Etch, yes I wipe off the panel with PRE before it drys. Learned the hard way what happens if you don't. Applying filler to bare metal is a good route. After all the time and effort to strip each panel, I was concerned about surface rust returning before I could get to the body work. Marten I use 2 3/4" wide sticky back autobody paper, mostly Norton gold. I tried several grits, doesn't matter, they all nub up.
Thanks all. I appreciate the help.
Bob
Thanks all. I appreciate the help.
Bob
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More Turbo
Joined: Jan 2016
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From: Scotland
I am not saying this is true because I have done it myself in that past but it is recommended that you keep the paper dry when sanding on primer because it can absorb water. I know epoxy is more waterproof than usual but I guess the same applies albeit to a lesser extent. If the paint hasn't cured then the paper would clog regardless.
Elder User
Joined: May 2007
Posts: 766
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From: south Fl.
All great information provided above, I have found that different brands give different results. My last few projects I used epoxy primer and high build urethane from Speedokote, the epoxy dried nicely and the high build sanded very easy. It can be purchased on Ebay but I prefer ordering it direct, I always speak with Brad. As far as Clear, I used Southern Polyurethanes, same thing, ordered direct and spoke with Barry.
Lead Driver
Joined: Aug 2006
Posts: 8,094
Likes: 654
From: Brentwood, TN
I use SEM Metalock and Advantage but from my experience, the marketplace has improved so much since 2K primers came out that all that I have tried seemed to work well. I have left 2K primered panels out in the weather for a year with no adverse effects. Couple this durability with smooth, easy sanding and you have a winner. I gauge the quality of the primer (and the prep for that matter) by how fine a feather edge can be gotten when sanding...if I block out a panel and a high spot peaks through, if that bare metal spot is lined by a feathered edge that I can see through without losing adhesion or stepping then that's a fine primer.
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Laughing Gas
Joined: Feb 2006
Posts: 892
Likes: 85
From: Western Massachusetts
This is a follow up. I bit the bullet and spent the extra money on SPI epoxy primer. Used it for first coats on front fenders. I didn't have the gun adjusted properly and had a big run and some major orange peel right off the bat! Oops. After fixing that all went fine. The tech sheet says it can be sanded after 12-16 hours. The next day I sanded the run and orange peel. I am amazed how well it sanded compared to the epoxies from Eastwood and Summit. It didn't plug up the sand paper. I will hit that section with another coat today to make sure there are two coats on it.
Another thing that impressed me, SPI has a tech number that you can call or text. I texted twice with questions and a guy named Barry answered within minutes. My wife always says "you get what you pay for".
Another thing that impressed me, SPI has a tech number that you can call or text. I texted twice with questions and a guy named Barry answered within minutes. My wife always says "you get what you pay for".
Fleet Mechanic
Joined: Jun 2015
Posts: 1,879
Likes: 295
From: Central Michigan
I used the 2 part epoxy primer from the Napa store ( can't remember the brand) and though I haven't sanded most of it yet, the parts I did sand sanded easily. I plan to cover it again on the outside of the truck with regular hi build primer when I am ready to actually paint color on the whole truck.
