Tamiya extra thin?

[AlanG]

On a side note, is it a good degreaser? Curious as i've fallen out with Gunk, it's messy, smelly gets everywhere and just doesn't clean up neatly enough for me and i've got a bike i'm needing to attack now it's part stripped and if so is it easy to get hold of in civvy street?

Mike it's a good de-greaser. It came about after Trichloromethane (Trich) became banned. But i can honestly say be careful with the stuff. It will take out the fat from your fingers and your body can absorb it. I nearly passed out with the fumes from it when someone was using it in a torque wing box on a VC10 as the fumes are heavier than air. Hence to say i hate the smell of it now.

[stona]

I wouldn't splash MEK or any other solvent around. MEK is an irritant but officialy at least only toxic in high doses/concentrations. The smell is quite sickly,a sweet smell is a property of many ketones and some were and maybe still are,used to flavour things like pear drops! I believe MEK is easily available for use,as Allyne used to , as a degreaser and also as a plastic solvent.

I'm not surprised they stopped using trichloromethane as that has been deemed carcinogenic. It will also put you to sleep,it was commonly known as chloroform before everyone had to use the IUPAC nomenclature.

A long, long time ago I was a chemist (in the chemical sense...Grad RIC). Soon gave that up!

Cheers

Steve

[Gern]

There's a company called E.M.A. Model Supplies Ltd that does a liquid cement called Plastic Weld (according to the label it's dichloromethane) which works like all the very thin 'cements' mentioned.

They're not adhesives as such. They actually melt the plastic and cause it to fuse together. The 'cement' then evaporates - usually in a matter of a few seconds - and the plastic sets hard again. But having melted and run together the two pieces are joined.

Like most things, it has it's pros and cons but it is a useful addition to the toolbox.

Gern

[stona]

Hi Gern, dichloromethane and methy ethyl ketone are usually the main components of the plastic cements we plastic model builders use. They both act in the same way exactly as you describe. This is why some people refer to the process as "welding" the join rather than sticking the two halves together.

When you run these types of thin cements into a join and then press the two halves together the ooze that you see is indeed molten,in the sense of dissolved,plastic. It is this that fills the seam making a simple clean up result in a continuous,no gap,join.

The two problems most new modellers seem to suffer from are getting those nice clean seams and cleaning off sprue attachments without messing up the edge/face of the part.

I showed my nephew and an assorted bunch of his air cadet mates how to do both in about fifteen minutes! They still need a bit of practice though,I didn't have time to show them how to polish a thumb print out of a canopy lol.

Cheers

Steve

[stona]

you could always try good old cellulose thinners. I have used this stuff for years to glue my models and can vouch for its effectiveness. Its used in exactly the same way as the extra thin cement but its alot cheaper , cheers tony

And why not! Cellulose thinners have as their main ingredients organic solvents. Typically,in order of concentration, Toluene,Acetone and our old friend Methyl ethyl ketone. There will be other chemicals,usually different acetates as well. It should,as Tony confirms,work in the same way.

Cheers

Steve

(It was a LONG time ago but organic chemistry was my speciality)

[Guest]

As a matter of interest, having bought some cellulose thinners from Halfords a while ago as a thinner / cleaner for lacquer paints, (Alclad and a Mr Color I have), I tired cementing two bits of sprue together with it and had very very poor results, it barely seemed to melt the plastic?

I'd quite like to try some MEK though as i've heard a few folk mention it as a model cement.

Steve, are you sure now that's the kind of Chemistry you were into? I've seen the 51st state and know what chemists are like, (in fact I remember a Chemist uncle of my wifes threatening to peddle viagra at our wedding)

[stona]

Steve, are you sure now that's the kind of Chemistry you were into? I've seen the 51st state and know what chemists are like, (in fact I remember a Chemist uncle of my wifes threatening to peddle viagra at our wedding)

'Fraid so. I gave up shortly after I qualified,about thirty years ago. You'd be amazed how often I still get asked if I could synthesise all sorts of compounds,usually illegal! I always say that with a fully equipped laboratory and library I probably could!

As far as cellulose thinners go there will be different recipes from different manufacturers. They will be based around the same compounds but it is quite possible that Tony has a mix with a higher proportion of plastic dissolving solvents.

Cheers

Steve

Cheers

Steve