73-87chevytrucks.com

73-87 Chevy _ GMC Trucks => Body, Glass & Paint => Topic started by: JJSZABO on October 12, 2007, 03:22:00 pm

Title: Undercoating
Post by: JJSZABO on October 12, 2007, 03:22:00 pm
Just undercoated the bottom of the cab.

I used Duplicolor roll on bed liner.  I know - it sucks as a bed liner, but wanted to try it as a undercoating - it was cheaper than Herculiner.

Prep:  I sand blasted the whole bottom, cleaned with laquere thinner, then wax and grease remover, then seam sealed the repair areas.  Then epoxy the whole bottom - let cure then applied the undercaoting.  Here is a picture:
(http://i123.photobucket.com/albums/o317/jjsabol/IM001176.jpg)
Title: Re: Undercoating
Post by: locdogg on October 12, 2007, 07:20:01 pm
looks nice--I just put a new rust free bed on my truck and Herculiner-ed the underside as well as the inside of the bed and tailgate
Title: Re: Undercoating
Post by: Blazin on October 13, 2007, 08:40:33 am
Looks good. I hope you sanded the epoxy primer first though.
 I did the same thing to my 86 cab but used SEM spray on bed liner. Used SEM self etching primer underneath it, and sprayed SEM acrylic black paint over it.
Title: Re: Undercoating
Post by: 87GMC2WD on October 13, 2007, 08:44:44 am
i used that SEM stuff in school on a utility trailer that we made with the same primer. CAme out pretty good. But on the underside of my bed and my frame i wirebrushed and used a 4in grinder than applied POR15. It works pretty good. i also painted my exhaust with it and it just baked right on and doesnt smell anymore.
Title: Re: Undercoating
Post by: VileZambonie on October 13, 2007, 10:04:59 am
Looks good! I've used the duplicolor liner and I've had problems with it sticking well. One really cheap excellent product I've used with great results is Rustoleum Hammered black. It looks good and protects well. It does take a while to dry though. I would say wait at least 48 hours before really working with it.
(http://images.orgill.com/200x200/6603146.jpg)
Title: Re: Undercoating
Post by: Captkaos on October 13, 2007, 10:44:58 am
I just put Durabak on my Crew Cab floor to seal it from any moisture before putting the carpet back in.  When I did the bottom of my cab in 2000 I painted it with POR15.
Title: Re: Undercoating
Post by: Blazin on October 13, 2007, 10:50:08 am
I used to use the Hamerite but a few years back the Kilz company bought it. I think they changed to formula. It doesn't work as good or last like the stuff from 10 years ago. The old stuff worked awesome over Duponts Variprime or tightly adhered rust, it didn't work well over bare metal though.
 I use this stuff, its the same as POR 15 but about half the price. If you want to spray it they have reducer, cut it by 10%. I spray this right on a frame after needle scale and a little wire brush work. it works good over sandblasted metal also.
http://4wheeldrive.about.com/cs/classicrestoration/a/aa042003a.htm
Title: Re: Undercoating
Post by: JJSZABO on October 13, 2007, 08:19:59 pm
Well.......no, I didn't sand the epoxy before I applied the undercoating :-[.  I am using Southernpolyurathene epoxy primer and the tech sheet says that the epoxy doesn't need to be sanded before applying body filler.... so .....I assumed that if the epoxy didn't need sanded before the body filler, then I didn't need it for the undercoating.  Time will tell.
Title: Re: Undercoating
Post by: Blazin on October 13, 2007, 09:57:08 pm
You said you let it cure is why I asked. Most epoxy primers are OK to recoat without sanding as long as they are not cured.
Title: Re: Undercoating
Post by: locdogg on October 14, 2007, 09:15:09 am
I used to use the Hamerite but a few years back the Kilz company bought it. I think they changed to formula. It doesn't work as good or last like the stuff from 10 years ago. The old stuff worked awesome over Duponts Variprime or tightly adhered rust, it didn't work well over bare metal though.
 I use this stuff, its the same as POR 15 but about half the price. If you want to spray it they have reducer, cut it by 10%. I spray this right on a frame after needle scale and a little wire brush work. it works good over sandblasted metal also.
http://4wheeldrive.about.com/cs/classicrestoration/a/aa042003a.htm

Blazin---do you know of anyplace that sells this online?
Title: Re: Undercoating
Post by: VileZambonie on October 14, 2007, 09:21:42 am
just google it

http://www.magnetpaints.com/underbody.asp
Title: Re: Undercoating
Post by: Blazin on October 14, 2007, 09:16:33 pm
I buy mine from one of the local auto parts chains. Don't know where you would get it online.
Title: Re: Undercoating
Post by: JJSZABO on October 15, 2007, 08:16:21 am
Is there any one "right" way? ???  It's like fishing - as long as you catch fish who cares how it is done 8)

As I observe, read  and learn new things, I have concluded that the path to the outcome may be different as long as the prep steps are done correctly.  Just my .02 worth.

The "you know what" is getting deep in here!!!! :D
Jeff
Title: Re: Undercoating
Post by: Blazin on October 15, 2007, 02:48:14 pm
If it works it works. I was just referencing in case there was more to be done or if someone else is thinking of doing the same thing.
 Basically if two components are compatible you can go over one with the other without sanding before the first is completely dry / cured.
 If the first is cured you should always have some sort of mechanical bond ( sanding ).
Title: Re: Undercoating
Post by: JJSZABO on October 15, 2007, 08:11:15 pm
It's all good ;)  I was trying to be witty - didn't mean anything negitive.  Blazin - you have WAY more experience in this than I do and I really appreciate the help you give us all. 

Thanks again for your help ;)

Jeff
Title: Re: Undercoating
Post by: Dragon on October 16, 2007, 02:49:54 am
If it works it works. I was just referencing in case there was more to be done or if someone else is thinking of doing the same thing.
 Basically if two components are compatible you can go over one with the other without sanding before the first is completely dry / cured.
 If the first is cured you should always have some sort of mechanical bond ( sanding ).
Very true, but if he applied it in his Garage, and didn't use a heat lamp, he more than likely only got it to "low-flash" cure(2-6hrs, depending on outside/shop temps)("High-Flash" is generally 20mins-3hrs, when baked or heated).  Depending on his outside Temps when sprayed and allowed to cure, it would take awhile if the temp and humidity was low.

If it was "Low-Flash" Cured, chances are good that it would still be able to bond, but you also run into the possibility of any excessively covered area sagging(running). Now if it was "High-Flash" Cured, and the Epoxy wasn't sanded before applying the bed liner, it will easily chip and flake with the slightest heavy contact. Any exposed Epoxy, will soak up moisture like a sponge, and would hold it to the metal(Like Bare Plastic filler(bondo)/DP Primers are notorious for..)...
Title: Re: Undercoating
Post by: Blazin on October 16, 2007, 06:32:58 am
Well I wasn't being a jerk, sorry if it sounded that way. Belive me I have had my share of uh oh, I shouldn't have done that this ways!!  ;D