So I've been working on my front bumper, which is a custom project for a long time now. It
s a long story, the question here is, for most of the bumper, I've sanded through everything. and reached bare fiberglass. There are some spots where the existing primer, are still showing.

Would it be of any benefit to spend the time sanding down the existing primer to bare glass?

Or it won't make any difference?

The original manufacturer used a gray primer, then a black primer on top of that. So it's kinda black splotchy, like a leopard print look.

 

just clear it and have a custom leopard print painted bumper!
i wouldn't worry about it unless you think you'll see high and low spots.
i'm sure you know this but i would go easy on how heavy you lay your first coat of primer. i've had them bust up on me before if you lay it down too heavy

 

You want as little primer on ther without overworking the piece if it looks like lepord print you sould be fine. If your sanding correctly the original primer will give u an idea of ur highs and lows make sure u fill any big lows before priming. Sand fill prime sand repeat as nessicary

 

^Ok. Thanks for the feedback.

Im thinking I'll be ok. Can never be too cautious, I've had too many "learn from my mistakes" moments. Which is ok, because I at least Im learning something.

 

Just so you know to be on the lookout for pinholes. These fiberglass body parts are full of them. Make sure to lay down a few good coats of 2kprimer then guide coat with black rattle can. Wet send the entire bumper with some 320 and work up to 600. If there are any little black dots left they are pinholes or low spots and will need to be filled and reprimed.

 

^oh hell ya.

I remember the first time I sanded into a fiberglass bumper and saw pinholes, I couldn't help but to laugh and think to myself "So I'm rollin with swiss cheese as bumpers...great."

You betcha, I'm sanding the bumper to get it ready for 2k. The whole car is almost ready for 2k.

 

Good luck bro, just take your time and get it all straight