firewall first time w/bondo & body work

So here goes below are some before and after pics. Actually there was before the before I had to weld some sheet metal from the inside to close up holes. let me know what you think I will try and take better pics of the after it was tonight so no the best light. Looks like I have gotten some orange peel so I guess that means more sanding. Wondering if I just use finer and finer grit to get smoother...
Using SEM trim black rattle can for paint

 

I don't think you want to sand the sem paint unless you plan a respray. It looks good. Why did you weld the sheet metal from the inside?

 

I welded from the inside so I could just tack up pieces just a little bigger than the holes. Then apply the bondo to and around the difference between the firewall and the new piece of metal. Other places were already done that way and I just continued the trend

 

You didn't mention any primer. Did you just apply the SEM directly over the mud? That's not necessarily the correct application, but not exactly wrong, either. Generally you would want to use a fill primer as a direct-to-mud coating, which you would then block sand to a smooth finish. For a firewall, though, bomb-can applied right over the mud works, as long as you're not going for pretty. LOL

 

So should I bring to metal/mud and do primer first?

 

Yes you should prime first, it will help with adhesion, and also, like he said above, it will seal the mud so it doesn't absorb the paint at a different rate and cause light spots. It will also allow you to get a smoother finish, because you will block sand the primer before applying the top coat. It looks ok for a firewall as is, but for future reference, priming will help both the finish and the durability of the finish. Some other tips, wiping the bare metal down with a degreaser/wax remover or even just some laquer thinner will make sure all the contaminants are gone, and wiping down with a tack rag will make sure all the dust is gone, so you won't leave dirt under the paint. It looks like you got that pretty good here, but after sanding primer, the tack rag will make a big difference. Looks pretty good for a first body work job though!