what sandable primer

[goshawks00]

Will some one give a quick pro and con for using 2k primer and polyester primer? This will be put on over an epoxy primed body... Is there any reason to use 2k primer?
Thanks for any insight,
Barry

[Bob K]

You can think of the polyester as filler, just like bondo that is applied with a spreader. It still needs 2K or some other sealer applied before you paint. The choice becomes whether to use the poly or not. To be sure, check the product sheet for your paint and see what substrate the paint can be applied to. I don’t know any that recommend application over uncoated filler, I could be wrong.

Bob K

[JCCLARK]

Is there any reason to use 2k primer?
Barry

Not really, unless you need the filling to be able to level the surface ,
like getting rid of scratches or minor blems.
that's what 2k is for.
Epoxy is far superior and all you need, it just doesn't fill very well.
But for a smooth panel with epoxy on it, nothing else is needed.
I prefer it that way, and will sometimes reprime epoxy 2 to 3 times
sanding between coats to get it straight and level just so I don't
use 2k. Epoxy provides much better adhesion and less shrinkage.:cool:

[goshawks00]

Thanks!! Maybe I didn't make myself clear... after the epoxy primer is on, I need to do the typical dent/straightening body work... Should this be followed with polyester primer or 2k ? There will no doubt be many layers as I try to get this all straight, as there will be some body work/filler work to do on especially on the hood and fenders... Is there such a thing as high build polyester spray primer?
Barry

[Len]

For the most part there are three catagories of primer that are the main ones used on the vehicles' surface.

1. Direct to Metal Primer... This is usually etch or epoxy primer that is used on metal (and other) surfaces in order to create a good bond with the surface.

2. 2K Filler Primer... This is applied over fillers or other surfaces in order to hide scratches and other small imperfections.

3. Polyester Spray Filler... This is a heavier material that is used mostly to tweak the level of larger areas. This primer is more like a spray on body filler.

In most cases you can use 2K over epoxy or etch primer to finish removing the surface imperfections before you paint but some 2K primers can be sprayed directly to the metal. Read the paint manufacturer's technical info for the products you're using, it's usually available from the paint supplier.

Polyester spray filler usually requires a spray gun with a 2.0 or larger fluid tip and it probably should be coated with 2K or sealed (or both) before it's painted.

[goshawks00]

Thanks all..
Len are any of the 2k primers easily sandable to body work with (leveling/filling low spots etc)... any manufacture recommendations?

How about the polyester types?

Thanks
Barry
ps got box today.

[Len]

The more important question is "What is available from a good supplier in your area?" Poly primers that have gotten good feedback here are Slick Sand and Featherfill G2. Most of the 2K primers are similar so I'd say get one that is available from the supplier in your area. Don't necessarily look for the lowest priced products because, paint is like tools and spray guns, you get what you pay for. So if the job is somewhat important purchase good tools and materials.

[Serge]

You can skip the epoxy and 2k steps by using an epoxy hybrid that fills both functions. That is, basically a 2k surfacing epoxy that can be sprayed direct to metal.

I like Valspar's DTM2000 series primers, it comes in Black, White and Grey. Its basically the same as the KD2000 from House of Kolor. HOK also has KP2CF that is an excellent filling epoxy.

As for regular 2K primers I like PPG's K36 shot over PPG's DPLF epoxy. K36 (or K38 that is slightly more filling) are very easy to sand....However you can find good 2K primers in all paint systems.

As for polyester primers I use Evercoat's Slick Sand. Len sells the slick sand primer. However, you need to think of polyester primers as problem solvers, not all around primers (except for fiberglass bodies for wich it is the best first step...but that's another subject). Polyester primer is used in stead of skim coat of filler on problem areas that require filling beyond 2k primer's ability.

Remember that the thinner a coating is the more flexible it remains, the thicker the more prone to chipping and cracking it is. You need to consider the thickness of your entire finishing system. The idea is to create the thinest coating that will do the job. So you need to use the right products in the right places.

The difference between 2k and polyester primers is that the 2K primers are paints, they are not formulated to build thick coatings. If you build them too thick, they are weak and unstable. They should be used to build the few mills that you need to get a pannel straight. Polyester primers however can be used quite thick because it is basically polyester resins like filler, its not a paint per say...its more a filler...