I discovered some rust around the windshield on my 82 F250. I was planning on grinding out rust and fixing with fiberglass. My questions are:
1. After grinding back to good metal should I use POR-15 first then fiberglass over that?
2. Windshield is out. Now I need to remove all old adhesive (I will ask installer to use Urethane adhesive as recommended here. When I clean windshield posts (using 3M fiber disk) I'm sure I'll go through paint to bare metal in some spots. Is POR-15 over the bare metal okay? The windshield molding will hide the area. Should I just paint around th ewhole windshield openning with POR-15 for extra protection?
3. Will urethane adhesive stick to the POR-15 okay?
4. Do I need to clean rust area with acid then use epoxy primer then POR-15 even if area can't be seen after reassembly?

I want to fix it right the first time - but the rust is under the cowl where it won't be seen once repaired so I won't need a professional to paint the area.

Sorry for the the long post - I want to do this right.
P.S. Body shop wants $1000 to make fix. I have pictures if someone can tell me how to add/post them.

Mike

 

>I discovered some rust around the windshield on my 82 F250.
>I was planning on grinding out rust and fixing with
>fiberglass. My questions are:
>1. After grinding back to good metal should I use POR-15
>first then fiberglass over that?
No need to go all the back to good metal, POR (Paint Over Rust) works best over rough and rusty metal. You can also put fiberglass IN with the por, just coat it on both sides and 'soak' it in the por15


>2. Windshield is out. Now I need to remove all old adhesive
>(I will ask installer to use Urethane adhesive as
>recommended here. When I clean windshield posts (using 3M
>fiber disk) I'm sure I'll go through paint to bare metal in
>some spots. Is POR-15 over the bare metal okay?
Actually it is the best, por does best over metal and ok over paint.

>The windshield molding will hide the area. Should I just paint
>around th ewhole windshield openning with POR-15 for extra
>protection?
The only concern I would have is coating the Por15 with something, you don't have to but if it'll see UV rays, you may want to. Por15 will do well all by itself.

>3. Will urethane adhesive stick to the POR-15 okay?
Por15 stops water from contacting the metal and has a porclin type finish, getting things to stick is hard. You can scuff up the Por but that diminishes the effect that it has on keeping out the water.

>4. Do I need to clean rust area with acid then use epoxy
>primer then POR-15 even if area can't be seen after
>reassembly?
This is overkill and redundant. You can clean the rust out then acid treat the surface rust (phosporic acid) then clean and apply a good 2 part epoxy primer

OR

use the por15 method.

I'd tend to use the Por15 where needed with some overlap to good metal, then use their topcoat stuff if it'll be seen or exposed to UV rays.

As far as Por15 goes:
clean to hard rust or clean metal
clean with acetone
apply phosporic acid (body shops or home depot under the Jasco label)
scuff with scotch bright 400 pad (body shop supplier)
clean with acetone
dry with hairdryer
apply two THIN coats of por15 allowing dry time between coats until light finger drag or tacky

the windshield should hold to the por because I think windshield adheisive sticks to polished paint.

>P.S. Body shop wants $1000 to make fix.
I'm surprised that you found a body shop that'll make that kind of repair. I'd really like to know what they were going to use. Most want to cut and weld.