Cheapest source of Epoxy Mastic 121

redrover

Active Member
#1
This question is probably best aimed at Paul testrider...

What's the cheapest source of Rustbuster's Epoxy Mastic 121 (black)? I've checked ebay and you can currently get a litre tin for £37.90 to the door, which doesn't seem too bad, but there isn't any choice for bulk buying. Just wondering if anybody knew of somewhere that would do higher volume for a good price?

It's been three years since I last under shielded the car, and I discovered a slight damp patch on the passenger carpet yesterday, so I took the sill covers off today and stripped all the under shield off to inspect. Not bad for original sills. Just a few pin holes that I need to plug, which is quite clearly the source of the water ingress.

Michael


IMG_0920 by michaeljallen19, on Flickr

IMG_0924 by michaeljallen19, on Flickr

IMG_0919 by michaeljallen19, on Flickr

IMG_0921 by michaeljallen19, on Flickr
 

redrover

Active Member
#2
..and also (probably aimed at Paul again), what's the preferred technique for bare-metalling to get the epoxy to stick? I've got some of those carbide paint/rust removal discs that I use on the Minor. Will they do? Or does it have to be proper bright metal?
 

rockdemon

Administrator
Staff member
#3
if you read the instructions they tell you it doesn't need to be perfect metal. Because i'd been welding i mostly welded it then covered it in zinc weld through paint as i went along.

I found the price varied but i only needed 2 lots to do the majority of the exterior bits i welded. The interior i painted with a less pricey alternative ... aldi's rip off of hammerite and that's still looking clean :)

Hope that's some help...

Rich.
 

redrover

Active Member
#4
Thanks Rich, top stuff. I was only concerned about the bare-metalling bit from various jobs I've read about on forums. Like this....
http://www.pistonheads.com/gassing/topic.asp?t=1025168

But I think in that case the bloke's problem was hammeriting it first, which obviously isn't going to give enough of a key. My concern is that the factory finish that P6 base units have (that sort of bile yellow colour from the Phosphate dipping) is also quite glossy, so would keying this with contour pads be enough? Or should I hit them with a carbide disc to be on the safe side?

Appreciate this makes me sound like a right tw@t.... "I'm concerned the factory fresh finish on my sills is too good for the rust proofing paint to stick to!" :wink: But just want to make sure it sticks properly.

Yes, I've hammerited the floors inside as well. The smoothrite type isn't that easy to use on sheet metal - it's either too thick or too thin going on - but I swear by the hammered finish one. I think there's something semi-flexible in it. I did my whole suspension in a single coat of it 3 ½ years ago. 12k miles later, they're still perfect. Grubby, but still fully coated.
 

rockdemon

Administrator
Staff member
#5
Reads to me like it's down to mixing coatings - i really wasn't that anal about preparing it - you know me, happy amateur :)

I think brushing it straight onto those sills is going to be fine. might be wrong of course ;)
 

testrider

Active Member
#6
I've always bought mine from Rustbuster and (unusually for me) I never thought to shop around for it. I think the 2 x 1litre epoxy and hardener is about £50 and might be enough for 2 coats on the floor pan/sills. Allegedly one coat is enough, but it's not so easy upside down and I could still see through some of the brush marks so I did two coats on the lot with a couple of days between coats.

As for surface prep, I scrape the underseal off then clean it up with white spirit to get rid of the residue, then clean off any paint and/or surface rust with strip and clean discs (get a box of them from eBay) on the angle grinder. Wipe down again to get rid of dust then paint straight on to bare metal. I only left the factory finish on in less exposed places or where it was impossible to fit the grinder (ie above the diff) and always roughened it with sandpaper first.

You can mix the paint in a jam jar before your degrease and wipe down as it has to settle for a few minutes before painting on. After that I sprayed cavity wax over it and the back of the panels prior to reassembly.

Sounds easy doesn't it? :D
 

redrover

Active Member
#7
Thanks Paul,

Doesn't sound like too much fuss to me. When you consider the amount of faff you need to warm/partially melt and then thin conventional bituminous undershield, and then try and spread it evenly with a brush (!!), it's not so bad. I've got some of those clean and remove discs, so will attack with that. Just concerned to get the best adhesion possible, as the circular strengthening dimples in the sill section won't be that easy to strip back completely, especially at the edges of the circles .... I know I'm getting a bit over-zealous about all this, but I just like to do things properly once only.

Did you put the cavity wax on top of the paint once it had dried? And if so, what's the life expectancy of that? I'm ideally looking for maximum coverage and protection for minimal future maintenance.
 

Dave3066

Well-Known Member
#8
testrider said:
I've always bought mine from Rustbuster
Me too.


testrider said:
Allegedly one coat is enough, but it's not so easy upside down and I could still see through some of the brush marks so I did two coats on the lot with a couple of days between coats.
I inevitably end up making too much of the stuff so manage about 4 coats before it goes off. If you leave it about an hour between coats the mix starts to harden sufficient to prevent it dripping off and it leaves quite a good rippled finish with a brush.

testrider said:
As for surface prep, I scrape the underseal off then clean it up with white spirit to get rid of the residue, then clean off any paint and/or surface rust with strip and clean discs (get a box of them from eBay) on the angle grinder. Wipe down again to get rid of dust then paint straight on to bare metal. I only left the factory finish on in less exposed places or where it was impossible to fit the grinder (ie above the diff) and always roughened it with sandpaper first.
Only difference to that is that I use Autosmart's Tardis to degrease.

testrider said:
You can mix the paint in a jam jar
I use an old christmas pud container to mix mine :D Once any residue dries it can be pealed off and the container used to mix again.

As for longevity, it's pretty hard wearing stuff but it can suffer impact damage on edges etc. I did the whole back end of the V8 and after a year's motoring there were only a couple of chips.

Dave
 

testrider

Active Member
#9
redrover said:
I've got some of those clean and remove discs, so will attack with that. Just concerned to get the best adhesion possible, as the circular strengthening dimples in the sill section won't be that easy to strip back completely, especially at the edges of the circles
That's why you'll need quite a few discs - when they're new the edges will get right into those circles. Once the edges are worn off you can sue them on flatter sections. I use a knotted wire cup attachment and a powerfile which is a half inch wide belt sander to get into the corners.

Be careful with rust converters if you're using them as most are affected by cold and/or humid weather which stops them working.

Spraying cavity wax over painted sections makes the water bead off and allows you to see if there's any damage to the coating rather than hiding it like underseal would.
 
#10
Dave3066 said:
testrider said:
I've always bought mine from Rustbuster
Me too.
And me.
Dave3066 said:
testrider said:
You can mix the paint in a jam jar
I use an old christmas pud container to mix mine :D Once any residue dries it can be pealed off and the container used to mix again.
I grab a plastic bottle out of the recycling bin and cut the bottom off, then throw it away after use.

Has anyone used their "CUSTOM EPOXY 421 RUST PROOFING BODY PRIMER"?
http://www.rust.co.uk/products/category/32736/custom-421-epoxy-body-primer
 

quattro

Well-Known Member
#11
Willy Eckerslyke said:
Dave3066 said:
testrider said:
I've always bought mine from Rustbuster
Me too.
And me.
Me Four 8)

The hole you can see on the outside of the sill could be how the water gets into the sill section, but it cannot get into the carpet without there being similar holes at floor level on the inside. Have you lifted the sill carpet and found where it's comimg from?

Richard
 

redrover

Active Member
#12
Hi Richard

There is some pin-holing on the outside of the sill, which is obviously letting into the box section, but the holes that are letting into the floor are here:

image by michaeljallen19, on Flickr
On the inner edge of bottom of the inner sill. There's a bit of thinning around some of these holes (only about 2" or so), so I'll cut all that out and replace it. And the bottom of the angled section of the jacking point (the natural rust trap!) has come away, so I'll reattach that - not that I use them anyway.... I'm too paranoid for that!

Michael
 

testrider

Active Member
#13
redrover said:
And the bottom of the angled section of the jacking point (the natural rust trap!) has come away, so I'll reattach that - not that I use them anyway.... I'm too paranoid for that!

Michael
The jacking points are quite good - once they've been rebuilt! You can put a drain hole or two on the bottom of the jacking point when you rebuild the lower part, sort of shown below.

 

redrover

Active Member
#14
Looking good! Mine is currently a bit holey at the bottom. Will get a decent pic when it's light. I've got some decent 10 gauge steel that I might use to strengthen it. Problem is, if I do that to one, I'll want to do it to all of them! Will post back with pics. Off to New York on Saturday so unlikely to get much done for a few weeks. Will see what I can do by candle light this week tho.

Michael
 

redrover

Active Member
#16
That's the first place on my list. I haven't got too much interest in the Empire State. I'll go and see the lobby, but I think most people want to look at the top, and you can't see that when you're on top of it! The Rockerfella is also just a little artist colony's play thing, and a far more interesting piece of modernist design.
 
#17
Indeed. Also, we found them very relaxed, allowing us to spend as long as we wanted at the top - we were there as the sun was setting which was very atmospheric.
2 freebies:
Staten Island ferry - good view of the Statue of Liberty and Manhatten. And we were treated to the mother of all electric storms!
Brooklyn Bridge - subway to the other side then walk back across (perhaps not in winter though).

Have fun!

(Sorry for being off-topic folks, too tempting to relive old hols.)
 
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