Underseal Vs Hammerite

[alansti]

Hi All,

I'm spending a lot of time de rusting & repairing the floor on my Tr7 DHC, I'm painting on many different colour coats of Hammerite, ( makes it more interesting & insures that each coat is fully covered). Should I underseal over the Hammerite or leave it alone & touch up rusty stone chips every now & then? My main concern on underseal is that rust can travel hidden behind the underseal layer & it's a real pain to get off.
[?]

[FI Spyder]

The problem with underseal is that over the years it hardens then cracks. It's these cracks that allow the moisture in and because there is very little surface area exposed it doesn't get much of a chance to dry out and therefore promotes rust formation.

I'm not familiar with Hammerite as it's a UK side of the ocean product. Over here we would tend to use POR-15. As for under seal my feeling is this: for areas like in the wheel wells and the under side of sills I use undercoating as it takes a good drubbing from stones and the like being kicked up by the tires. Other areas that are not in line with the tires I like to use a product that will remain soft and will migrate to the remote nooks and crannies and heal from any chips it might occasionally receive. This would be any of the waxoil type products or something like Ship-2-Shore. These products get washed away after a few years and occasionally need to be resprayed (easily done with a engine cleaning wand and compressor. Underseal needs to be checked every couple of years as well to check that it is pliable and it's bond is still good by using a small scrapper.

Regardless of method I always inspect every year or so the underside of my cars to catch any suspect areas. The older the car the more likely it has areas that are prone to rusting.



TR7 Spider - 1978 Spitfire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

[REPLIC8]

Welcome to the forum,
My car's been protected underneath with hammerite for the last 23 years. It's just had it latest repaint, the previous one was 12 years ago. It's still rust free so it must work OK. As F1 Spider says, just touch it up every year as part of your routine maintenance. I wouldn't use underseal as it causes more harm once it deteriorates. You should use Finnegans No.1 primer (the pink stuff) on the bare metal before using the Hammerite.

[img][IMG]http://i473.photobucket.com/albums/rr92/REPLIC8-2008/small_P2060309.jpg[/img][/img]

[img][IMG]http://i473.photobucket.com/albums/rr92/REPLIC8-2008/small_P2130316.jpg[/img][/img]

Andy
1981 UK SPEC TR8

[staningrimsby]

The underneath of my 7 has been completely undersealed then i was told it can crack and let the moisture in just like F1 Spyder said, my MOT tester then said to go over the whole lot in waxoyl and that would seal it and prevent the moisture from penertrating the underseal.

Also while my engine is out i have ground down the chassis rails in the engine bay, then i hammerited them and sprayed them with stone chip, but i didn't primer before the hammerite [:I], have i made a boo boo [?]



1980 2.0 DHC (soon to be 16v) - Polly.

[DNK]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by FI Spyder</i>

...
I'm not familiar with Hammerite as it's a UK side of the ocean product.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Actually World wide. Home Depot and Lowes carry it.
I use the brown for my 6 as it's close to a color I like

Don
"No More Cars For You"
71 TR6- Perpetual remodel
80 TR7 V8 Kick in the pants

[alansti]

Hi All, thanks for the replies & welcome, I feel better now that I haven't used underseal but it sounds that even if I had it wouldn't be too bad if coated with a wax spray. Before the Hammerite layers I clear any rust using Jenolite coats & wire brushes in an angle grinder. Then a coat of rust preventer that turns the metal a blue black, then normal primer then lots of coats of wrong colour blue that I pick up cheaply from stalls at the local Market in Wellesbourne. My Tr7 is Cavary Blue but I've found that Ford Galaxy Blue is quite close at least until it's road worthy tested & ready for a proper respray.

[alansti]

To Staningrimsby, I think that Hammerite shound be OK withiout Primer but keep an eye on ir if it chips, at least if there is a primer layer underneath it'll provide another barrier.

[staningrimsby]

Yeh i thought it would be ok i have used it before that way with no problems, as for the chassis rails they are also coated in stone chip and will be wax oiled prior to the engine going back in, so should be protected fine.[:D]



1980 2.0 DHC (soon to be 16v) - Polly.

[REPLIC8]

Stan,
It's fine to use hammerite on the bare metal, it's just the primer adheres better & tends not to flake over time.

Andy
1981 UK SPEC TR8

[staningrimsby]

Cheers Andy, going to crack on with the engine bay again tomorrow, hoping to put the sprint engine in at the end of the month with any luck.[:)]



1980 2.0 DHC (soon to be 16v) - Polly.

[saabfast]

I have found that Hammerite primer/undercoat chips very easily, even after applying the top coat. I have used it with brush and spray applied top coat and it always seems to chip back to steel very easily if knocked. Seems like it does not adhere to the bare steel very well, the Hammerite top coat seems to stick better on its own.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
'81 TR7 DHC

[Bobbieslandy]

I used a Hammerite and waxoyl mix. i wire brushed my inner wings back to bare metal, applyed 2 coats of Jenolite then totally went to town with the underseal mix. I can't comment on it's durability, it's only been on there a few months though.

http://cgi.ebay.co.uk/1LT-HAMMERITE-UND ... 4155cfb712

I plan to get the car chemical stripped soon so this was only a temporary fix, ideally i'd like a really tough underseal, i assume there's some kind of super tough coating around?

Rob.

[cozyheatdave]

I had the body shop do a professional truck bed-liner material.
I wish I knew what brand. But it was applied to bare metal and looks great.

[Beans]

If it was applied to bare metal than I'd make sure you get those grey bits covered.
Because that should be bare metal !

<center>
<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>

[FI Spyder]

The best spray on truck liner is Line-X. It is sprayed on hot and can give a smoother or more textured surface. It is available around the world. It is only sprayed on by a dealer as it requires specialized commercial equipment. The cost would probably be about $600 or so.

It was the only product that passed the US DOD test where they sprayed it on a mobile home and exploded a bomb beside it, it was the only trailer to survive. It was featured on the TV show Trucks a few years back when Stacey David was hosting it.

It can be coloured to match your paint. You would effectively have to present them with a body shell as you don't want to get it on anything else. It will not come off....even if you try to explode it off.[:0]

http://www.line-x.com/

I was thinking of doing a Spitfire a few years back. I saw it at a home show where it was sprayed on the under side if a utility trailer. Not cheap but the best you can get. I would imagine the soundproofing would be pretty good too.


TR7 Spider - 1978 Spitfire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT