Undercoating question

[lancemb]

I know some do not like undercoating, but all of the 57 and 58 Buicks myself or my father has owned came with a thick undercoating, and in most cases this kept the underside very solid.

Anyway, on one of the 57's the rear floor pans were replaced, and I want to undercoat them with something similar to the original. The stuff they were undercoated with when first replaced is very thin, as opposed to the thick stuff that the factory used. Any suggestions on what kind best mimics this?

[buick man]

I am in the process of tracking this stuff down as well. 3M makes a line of undercoating with various chunk/thickness ratios but have yet to go there. You can go on line and look into that or your local auto paint jobber can help as well. It's a matter of finding the right finished tack and texture look. I believe GM has a line as well. You may have to mix 2 or 3 different ones together to get the "Correct" finished look. Let us know what you come up with and I'll do the same.

[Guest shadetree77]

Funny this topic should come up....very soon I'm going to be spraying some of this stuff on my wheel wells and a few other areas. I'm going to try the Rust-Oleum brand undercoating in a rattle can. As soon as I try it, I'll post back here with some pictures. If you are looking for a thick coating, I don't think you'll get it from a rattle can. Try bed liner products for a thick coating. For that "chunky" look, there is a product called Monstaliner from the Magnet Paints company. I used it on the floor of my Tbird and it looks great. Been on there for several years and hasn't faded or cracked. It's a thick coating and comes with a specially designed roller that gives it that chunky finish. I can provide pictures if you want. Just let me know. Good Luck!

Edited November 22, 2012 by shadetree77 (see edit history)

[avgwarhawk]

The chunky finish might get more chunky with several coats. If you have a 4x4 shop in your area check to see if they carry undercoat in the can. My bro-in-law gets it from a 4x4 shop. Works great.

[buick man]

Great replies guys. I think the mantra here is find an exact as possible match to what is already existing or to replace with as similar look/material. This is why I suggested you may have to mix some of these together to get the right "look" and may have to reduce them to a large extent in order to get that faded and flatten out weathered look. If you are going the total correct route.

With this said I just had a flash thought. There may very well come a time sooner then later when a restoration will not result a bright and shiny work up, but rather a pure duplication of patina and wear. I have already talked to one professional restoration shop owner I know and he has noted a large increase in a restoration whereby th owner requests everything new but the outside paint or if painted to look patina weathered. Kinda like the faded jean look of years back.

[NTX5467]

One question I might have is "Are you SURE the undercoat on the underbody, which you're seeing, is really factory-applied undercoating rather than something a dealer in more rust-prone regions of the country might have applied at "point of sale"? Even on a "higher priced car", as a Buick was back then, I can't see GM putting in on at the factory unless there was a really good reason to, or if the additional cost was covered by the higher cost of the particular model of car, comparatively speaking. I can see wheel wells and such, but not underbody parts per se.

There was a undercoating brand which was introduced in the later 1980s, which was "in bulk" and advertised "factory finish" (or something of that nature). To me, it looked more like a dried cow patty than the undercoat I remembered being used by the factories (Chrysler, in this case) back then.

The problem with finding a "heavier-bodied" undercoat is that it can very well need a special gun to apply/spray it with. The other thing is that if a thinner-bodied undercoat is put on in thick coats, there is a great possibility for most of it ending up on the floor rather than on the vehicle. As with paint, multiple lighter coats are best. We had a body shop customer who had a gallon bucket of "stiff-bodied" undercoat, which he used for the inside of door panels . . . applied with a short piece of leaf spring end (it was THAT thick).

Perhaps the recently-advertised "On TV" "Great Seal", spray-on rubber coating might have the texture you might desire? It's paintable and multiple coats might have the desired build thickness and texture you're trying to replicate?

Please keep us posted on your progress!

NTX5467

[buick man]

My 57 has it on the bottom and it's been a southern california car from day one. Yes I think you are right regarding application of the under seal. In the Buick Chassis Manual and the Body Fender Shop Manual it goes into the bulk "Buick" undercoating that Buick supplied to their dealers to make a extra buck on. It also has a name come to think of it. I will have to go back through it to see what they called it. Yes it takes and it still takes a special gun if you want to do it "Right". I bought the gun as they are around $ 25 or so and has the special spray end to give the right texture and look. Never hill boy it and go out and use rattle crap cans on any portion of a preservation or restoration project. Cause, in the end it will only look good if you don't know what to look for or you have to squint your eyes shut in order to make it look even close to acceptable.

[Guest 54fins]

Hate to be contrarian, but I would not undercoat the car. Undercoat serves no purpose, it holds in salt and moisture and makes the car difficult to near impossible to maintain. It will only detract both functionally and in looks. The original undercoat was removed, so the only thing is replicating a mistake for historical purposes. However, seeing the embosses on the pan is far more interesting than seeing black tar. I have seen some light undercoat applied, without making a mess of the undercarriage. If you did get lucky and you had good solid metal behind the tar, show it off! The undercoat would actually be used to cover up bodywork issues that you don't want to deal with. The tar also plugs up drain holes. The best thing for the metal is let it breath, otherwise dirt and water set up a corrosion cocktail. As you can see, I hate undercoat. Every car with undercoat has always been a problem, just lots of hidden rust and hours of trying to remove it.