Posted by Keith in Washington on Friday, February 17, 2006 at 11:02AM :
In Reply to: Blasting vs Chemical Strip posted by Steve in PA on Thursday, February 16, 2006 at 9:55PM :
The method depends on the condition of your truck and your preference.
I would not use chemical dips for any truck. Yes they can get into areas that never can be blasted but you can get weeping afterwards. That is not great after you just painted it.
Blasting:
1) Media blasting (Plastic) is great for thinner metals and trucks that have not been torn down totally. It is not good for rust removal. If you have a rusty truck you will need a more agressive blasting. One shop in my area will send parts where the paint has gone bad to a plastic blaster as there is little surface work afterwards except for a light sanding to remove residual plastic. It gives a much nicer finish and cost them less than paying labor for sanding. You can actually leave the rubber or stainless trim or even the glass in place without damage. It will polish the stainless and the glass will be fine unless you come at it point blank.
2) Media Blasting (Garnet Walnut) I use a shop that uses this method. It is not cheap on old military paint (that stuff is tuff). This is a very fine grained garnet with walnut shells to soften the impact. It cleans the metal very nicely and will get rust out. But it is not super agressive and will not warp panels. This is a good in between moderately agressive blasting technique. The surface comes back with a very fine patina that will polish out with a couple of passes of 220 paper. It actually provides a great grip surface for your primer. Much better for the primer than plastic media blasting.
3) Standard sand plasting. Very agressive not good for body parts. All but the best operators will warp your sheet metal. It can be used for frames. I took my bumpers in one day to a shop and when I got them back they were very rough. I asked why. Simple, was my answer. He is required to use steel shot for blasting by city law. It reduces the dust problem.
My current Willys project has very little rust so I will most likely use platic media blasting on it.