An adhesive question

[Tim StevensParticipant @timstevens64731]

I need to stick a sheet of aluminium about 500mm square to a similar sheet of plywood. The result needs to be permanent, heat resistant, water resistant, vibration resistant, fuel and oil resistant, and neat. So, what adhesive do I use?

Perhaps the poly-urethane stuff used for car panels?

Any other ideas?

Thanks, Tim Stevens

The actual job is the scuttle of a vintage motorcar which has been attacked by woodworm and old age. Bit like me, really …

[Tim StevensParticipant @timstevens64731]

To laminate wood and sheet aluminium

[Michael GilliganParticipant @michaelgilligan61133]

Tim,

Surface preparation [of the Aluminium] is by far the most important factor.

Phosphoric Acid is useful, but you can often get away with mechanical abrasion; IF you can clean off the dust, and apply the adhesive within about 30 seconds. [Oxidation occurs very quickly]

MichaelG.

[Harry WilkesParticipant @harrywilkes58467]

Some years back I needed to paint ali sheet and a friend who at the time lectured at the local collage suggested I used a mordant wash link it was for me a total success

H

[Dod MoleParticipant @georgeclarihew]

Any idea what originally attached the aluminium to the plywood? and use the same stuff as the original manufacturer used.

Like yourself I am thinking adhesive with the properties you require is quite exotic.

Rubber based contact adhesive would do for all but petrol resist

Cyanoacrylates do for most but moisture.

Arardite types would do for most but heat and vibration, so you seem to be asking a lot from an adhesive.

So unless you know a good welder – looks like you could be stuck.

Sorry

[Michael GilliganParticipant @michaelgilligan61133]

Posted by George Clarihew on 27/05/2017 21:17:40:

… so you seem to be asking a lot from an adhesive.

.

**LINK**

https://www.jaguar.com/about-jaguar/reliability/aluminium.html

MichaelG.

[Ian PParticipant @ianp]

Why not use a contact (impact?) adhesive like Evostic?

You dont quantify temperature and some other factors. thickness of the two item is relevant too. Once bonded I dont see where the waterproof requirement applies, aluminium obviously is not porous and presumably that is the side that sees the weather.

Used correctly Evostic will securely bond your two materials and am sure will comply with your list of properties (I'm presuming its flat rather than a contoured surface). As an alternative, 3M and others make sheet adhesive to bond trim in automotive applications and I know from experience that some bonded parts are together for life!

Ian P

[Bill PudneyParticipant @billpudney37759]

One way or another, I've done a fair bit of sticking al. alloy to wood. The thing with al.alloy is that it oxidises instantly, and will continue to oxidise pretty much forever, unless you do something about it. This is why it is so difficult to glue al. alloy, the surface of the metal is always changing. So, give the surface of the metal a really good clean using a degreaser type solvent, a light abrade, then another degrease clean. Then paint the surface to be bonded with an etch primer, I would use an Alodine (google it) type product because I know it works. Follow the instructions. Then to bond the metal to the wood use a good quality, long cure epoxy (24 hour Araldite would be the basic choice). Arrange everything so that it can be clamped and warmed whilst the adhesive is curing, and then mix and apply adhesive, clamp up, warm up and walk away from it for a day, and bingo!!

cheers

Bill

[clogsParticipant @clogs]

thought "Gorilla" glue fixed everything….hahaha…..

doing the turn, the expression when I lived in S.Africa..was.— "Magicone" = Silicone, that also fixed everything……

I also used "SIKA-FLEX" adheisive for laminating body panels Steel-Wood-Ally but NEVER where heat is a factor….seems to be impervious to fuels when cured (24h), once stuck down tho, no-way will come apart…..

bit like No-Nails, the glued item will come off the wall but removes the plaster as well……good luck……

let us know what you use please……..Clogs……

[Mick DParticipant @mickd41895]

Hi

From experience, the best type of 'adhesive' for this situation, in my opinion, is polysulphide sealant, applied as soon as possible, (within a minute if possible), after degreasing and lightly abrading the surfaces to be joined.

Done correctly it will last 'forever' as you'll find out should you ever wish to remove it.

Regards Mick

[Chris Evans 6Participant @chrisevans6]

I have built a few cars and rebuilt a few others. My bulkheads where made from thin ply and aluminium sheet bonded to it with either an araldite style of two pack when it could be scrounged in quantity. The others where done using regular resin as used in fibreglass work. None failed in use and a trials car has a hard life.

[Barnaby WildeParticipant @barnabywilde70941]

Aren't the modern Lotus sportscars aluminium chassis glued together?

[MichaelRParticipant @michaelr]

Evostic will do the job, use the 528 if applied correctly (Let the adhesive dry on both surface's ) the bond is instant and won't move.

Mike.

[damianParticipant @damiannoble34800]

+1 for 528 adhesive.

[mark costello 1Participant @markcostello1]

As an aside I have read on the 'net that a boat builder was putting the adhesive on the panel and then scrubbing the panel with somewhat coarse sand paper. It got the adhesive down as fast as the oxide was removed.

[ChrisBParticipant @chrisb35596]

As already mentioned by some before I would go for a Polysulphide sealant. I work for an aircraft maintenance company and consequently do a lot of repairs using aluminium.

Preparation for the alu sheet depends on what grade you are using, if it's an unprotected alloy such as unclad 2000 series 7000 series alloys the you will need chromic acid anodizing (alodine or alochrom 1200) or and etch primer.

If on the other hand you're using an aluminium clad alloy or 1000 series ( almost pure) aluminium, you can skip the anodizing part (it will not work any way) and just prime it.

Bonding with a Polysulphide sealant such as PR1440 B 1/2 or 2 (1/2hr or 2hrs curing time) will give you an excellent bond, but its a bit messy and you will need weights and clamps to weigh down the two sheets together.

http://www.ppgaerospace.com/Products/Sealants/Fuel-Tank-Proven-Standards/PR-1440-Clas-B-Fuel-Tank-Sealant.aspx

http://metalfinishingsltd.co.uk/treatments/alocrom-1200/

[An OtherParticipant @another21905]

I built a model boat hull about twenty years ago – wooden keel and formers with aluminium sheet glued directly to the wood using Evostik. The aluminium was simply abraded clean with emery clean. It is about 36" long, powered by a 5cc Diesel engine. It is still in useable condition despite years of water (fresh and salt), diesel, various oils, vibration and numerous collisions. Due to a design oversite, the hole for the propellor shaft had to be drilled after construction, which effectively cut the keel in two at the point the shaft tube went into the hull. The brass prop-tube was then also glued in place with Evostik, and has never shown signs of leaking or breaking free. I never expected the thing to survive as well as it has, so I guess that is as good a recommendation as any. I can't tell you the type number of the Evostik I used, but it was just a tine of the stuff bought from a local hardware shop, probably just aimed at general use.

I have tried on occasions using Araldite, and found it to be a complete waste of time – it eventually goes brittle, and breaks away from the aluminium, however the surface is prepared. Similar effects occurred with fibreglass type resins.

Two-part glues labelled 'polyurethane' seem to be better, but I have no long term experience of them.

[Russell EberhardtParticipant @russelleberhardt48058]

Polyurethane adhesives from Sikaflex or Loctite. I have used them for boat building and they will stick wood to metals very well. Best to use the appropriate primer from the same manufacturer for aluminium so contact them for advice.

Russell.

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