Body filler questions

[DAVEN1256]

This is my first real use of body filler and I have some questions. Right now I am trying to do cosmetic work on parts that are sound but have pitting in them. My subframe, a-arms, front bumper brackets, and things like that.

1) I am trying to get the mix ratio of hardener right. I did some experimenting. The first two times, I added too much and it set up too fast. The third time, I had about three minutes to spread it before it started to set up. Is this about right or should I try less hardener. Is there a standard "working time" before set up that tells you your mix is right?

2) How long after you apply the filler should you wait till you start sanding.

3) How long should you let the filler dry before applying paint?

4) How long can you leave the filler exposed before you put paint on it? Will the filler start to absorb moisture if it sits exposed too long?.......and cause problems with the paint later?

5) If you wipe it with wax and grease remover before painting, is there a certain amount of time you should wait to let it completely evaporate out?

6) These parts were already sandblasted and epoxy primered. I am putting the body filler over the epoxy primer. I am going to use Eastwoods 2K Chassis Black for the final coat........should there be a primer between the body filler and the final coat.......and if so, what is recommended?

Thanks.............Dave

[tmodel66]

Dave keep in mind I learned on the job and have no formal training but worked in body shop for years. I'll try to give you MY opinion .
1) 3 to 4 minutes is a good working time. You'll get the feel after a while and get it to suit your working ability.
2) I stay pretty close to bondo and start working as soon as you can. It will go thru a heat and after that go to work.
3) Primer goes next. As soon as you finish sanding you can prime and paint. A good 1K or 2K primer. Nothing special.
4)As with anything humidity plays a big part. If your in a shop with a little control over temp and such you can leave it exposed without any trouble for a week or so but I always primed soon after finish sanding because of bare metal flash rust.
5)No set time in mind but you can read the TDS (instructions on the can) as to how long to wait but 5 -10 minutes.
6) yes on primer before paint on anything. Exposed filler,bare metal, anything that's exposed gets some kind of primer prior to paint.. I used 2K on all my parts.
I'm sure you will get other opinions so you will have more info to work with but it's not hard after you get going.

[BillOhio]

I was always told not to wait to top coat epoxy primer too long or you lose the chemical bond. If i needed to fill pits, i would use filler on bare metal than epoxy prime.  Lately i found a product great for pits. Its called icing and comes in a tube. Nice to use product

[DAVEN1256]

Thanks for everyone's replies.