For plastic

I've put this on other forums and thought I'd spread the word. I've only  just found this out although I suspect that everyone else has known  about it for ever. As ever, common sense is needed:

I've heard all the horror stories about the use of this stuff, but I'm  fed up with paying exorbitant prices for glues. I found some straight  Methyl Ethyl Keytone, namely the stuff that plumbers and drainers use to  prime plastic drainage/sewerage pipes before gluing. I work in our  double garage with the doors and windows open which gives a nice flow of  air even without a fan. I don't leave the container open, so I'm not  breathing the fumes in anyway. It's doing a magic job of gluing a Ratio  Kit together and at A$8.00 for 250ml, I'm well pleased.

As I say, common sense.

Slaters were selling it as Mekpac for years. It's a lot stronger than liquid poly but beware with some plastics. It can melt them. Horrible smell to it as well.

Hi Peter,

You're solvent welding not gluing. Unlike most products such as Testors or Humbrol, it does not contain styrene monomer which acts as a filler/cement, or aliphatic acetates which slow down the evaporation rate. If it's plumbers priming fluid it contains a few other things besides MEK - normally acetone, tetrahydrofuran and cylcohexanone. And it's meant for PVC, not styrene.

I wouldn't rely on windows and open doors to get air flow, use a fan so that you definitely know it's being blown away from you to the great outdoors. Eye protection and a positive ventilation system are recommended. Plus an appropriate fire extinguisher.

Unless you're building a lot of kits, small volumes are a lot safer to work with.  One of the best I've found is Testors Plastic Cement, which contains "acetates and MEK".  One 30ml bottle lasts about 10 kits and costs around $5.00.

I used to use MEK, now I know better. Plus my condo association doesn't allow it. Neither does my insurance.

Nigel

As long as I can get it, Testors liquid cement is very good.  However, these products are getting rare in some places (nanny state) and some postal regs won't allow the shipping of chemicals like these (C&L requires that chemicals are shipped by FedEx).  I suppose people need to make their kits and commercial MEK is one way.

John

Thanks for the replies.

60019Bittern,
Mekpac I can't find anywhere locally.

Nigel,
I used gluing generically, but I understand the difference  :) I can use a fan, but the airflow through my garage from front to rear is such that I have to weigh light things down, but if it goes calm I do have a fan to use.

I've had no luck trying to get hold of the Testors product over here, which apart from the ridiculous prices is part of the reason for the MEK.

Brossard,
I agree with you, it is, as I said getting increasingly difficult to get stuff that works.

Hi Peter,

As long as you understand the safety issues it's fine to work with. The limit of 300 ppm is quickly reached without adequate ventilation. It's mutagenic and possibly teratogenic, as well as a skin and eye irritant, hence the need for proper ventilation and personal protection. The plumbing stuff even more so.

Nigel

Although I use Humbrol Polycement for some things I use D-Limonene for most styrene applications these days. 
Not only does it smell better (it smells of oranges), it doesn't evaporate as quick if you inadvertently leave the lid off and it's not as fierce as MEK so doesn't tend to warp the styrene - which since I do a lot of laminating of styrene layers is a big plus for me.

BCDR, Thanks.
Your advice much appreciated, but I looked on the interwebby for teratogenic and hopefully won't be getting pregnant at my time of life or gender.  :) I will watch out for the mutagenic properties though, thanks for the tip.

Rob, thanks also. I had a look for D-Limonene, but it seems hard to get hold of here. I'll have another look later.

Hi Peter,

Mutagenic means it will cause mutations in bacteria by messing around with the DNA (one of the standard toxicology tests, as is teratogenicity, which is probably a very minor issue given the demographics in this hobby). Of more concern is the well documented neurotoxicity. MEK is gradually being phased out in favor of less toxic solvents. Hence it's increasing lack of availability. Same situation as lead-containing solder - the substitute is not quite as good for our purposes.

Tamiya do a limolene-containing plastic solvent/glue. Yellow cap.

My concerns about quantities above 25 ml or so is that these solvent-based glues are all very flammable. The vapor is heavier than air, and will track (like ether) to a heat source. Anything around 500 ml or so should probably be stored in a fire-proof cabinet. It changes during storage and exposure to oxygen in the air, and apparently can become explosive. One of the reasons for buying small quantities often.

Nigel



 

Thanks again Nigel.

I do have a steel locker which is outside the house. I wasn't pleased when one of my sons brought it home from work, but now use it for storing volatile things in. My wife won't fit in to it though.  ;-) :)

I'll have a look at the Tamiya range for the solvent you mentioned.

Luckily for me I inherited two old working fridges when we bought the house, they and another have been built into the railway shed. Two are used for small quantities of volatile substances, glues, paints and thinners mine and SWMBOs art stuff. The other larger fridge is more important, it's full of cider…( Unless I've used some) :lol:.We have a broken 6 ft tall drawer freezer , this will be soon fitted outside my workshop for larger quantities of The nasties. A lock will be fitted although we have no children around here.

These things instead of going for scrap, can come in handy eh. Haven't had a cider for years. Maybe it's time I tried one.

Hi Q,

Domestic 'fridges are not vapor-proof, and are not the ideal place to store solvents.  5-8% ethyl alcohol containing alpha acids should be fine.

Nigel

[user=711]col.stephens[/user] wrote:

Slater's 'MEK-PAK' is actually Halogenated Aliphatic Hydrocarbon NOT Methyl Ethyl Keytone.

 

Terry

Hi Terry,

That covers quite a few things from chloroform up. Bit naughty of Slater's to use MEK when it doesn't contain methyl ethyl ketone. I'm sure any poison center would like to know what it as well.

Nigel

[user=1632]BCDR[/user] wrote:

Hi Q,

Domestic 'fridges are not vapor-proof, and are not the ideal place to store solvents.  5-8% ethyl alcohol containing alpha acids should be fine.

Nigel

I wasn't expecting them to be, but the working ones with the volatile substances in, are so much colder than the shed, they considerably reduce the evaporation rate..The big old freezer will be outside ( but sheltered from the rain.)Out in Saudi we had to store an 88 gallon barrel on volatile cleaning agent in a lean to sun shelter on the side of our building. I remember reading the label and it's flash point was lower than the air temperature during the day!!!!



 I only filled up our "in use" bottle at night…..

Hi Q,

As I suspect we both know, it's not the vapor or flash point that's the issue, it's whether the electrics are shielded (and spark free). Anything with open brushes…

I remember opening a dusty storage cupboard in the 1970's and finding a large bottle (around a gallon size) half-filled with dry yellow crystals, and a yellow crystal-encrusted Bakelite cap. I thought "flowers of sulfur?". Lying on the shelf was a hand-written label - Picric acid. Apart from its use in histology (the "Christmas Tree" stain), it was a favored explosive in WW1 (Lyddite - lots of bang for the weight). And unstable in the dry crystalline form, especially in the presence of any metals except tin or aluminum. The bomb squad gingerly removed it after clearing the neighborhood for a half-mile radius. The encrusted cap was the issue - enough friction there to set it off if opened.

We work with a lot of potentially hazardous chemicals in this hobby, knowing what you're dealing with is common sense. Which is why things like "halogenated aliphatic hydrocarbon" get me concerned. Presumably haloalkanes, with dichloromethane a good example of one that can be used for solvent welding. Is that what MEK-PAK contains? I'll ask Slaters.

Nigel

Who needs electrics, the parking bay was next to it, then the road and then  the perimeter track of the airfield, complete with fighter jets.
And of course most Saudis are avid smokers…

A bit late but there's no problem if you've got cotton wool pressed firmly in to both ears.  

Hi Pete,

Just add some rose-tinted glasses.

Nigel