No Plastic - I'm Puzzled

[niall Y]

I've just been mixing up some shellac from flakes - the first time for many years. And, I had to look up a recipe to check quantities. All fine, so far, except it cautioned me not to mix up in a plastic container,

Now. I can understand that the Meth's/ Ethanol might leach something out of the plastic, which might in turn have an adverse effect on the French polish. However, the Meth's comes supplied in a plastic container - plenty of time - to dissolve nasties out of the plastic - And the last lot of French polish I bought, also came in a a nice plastic container.

Am I missing something here?

 

[John Brown]

Maybe there are different types of plastic?

 

[Ollie78]

It will melt certain plastics, stuff like random yoghurt pots, hence the warning. Best use a glass jar.

Ollie

 

[John Brown]

Many moons ago, when I was a mean and nasty person, I worked for a while as a paint sprayer in a giant washing machine factory(think stand up in the drum with outstretched arms size). Some of the fitters would come and ask for a drop of hammer thinners in a plastic coffee machine cup to clean up grease and stuff. I would give them some. They only did it once.

 

[niall Y]

Hmm,..... am still puzzled, Don't think plastic dissolves in methyl. or ethyl alcohol - at least not the last time I looked

 

[Ollie78]

Hmm,..... am still puzzled, Don't think plastic dissolves in methyl. or ethyl alcohol - at least not the last time I looked

It won`t melt through it straight away like harsher chemicals but will soften it over time and eventually break it down. I once left some meths in a random pot over the weekend and it had slumped like a jelly and started leaking when I came back on Monday.
Plastic is a term for thousands of different materials so they just warn you to cover everything so you can`t sue them.

Ollie

 

[MF1000]

Hmm,..... am still puzzled, Don't think plastic dissolves in methyl. or ethyl alcohol - at least not the last time I looked

Ethanol can slowly extract some of the components of hard clear plastic containers. If you need to use plastic something like Lexan is best - think higher end laboratory ware plastics

 

[stuart little]

Many moons ago, when I was a mean and nasty person, I worked for a while as a paint sprayer in a giant washing machine factory(think stand up in the drum with outstretched arms size). Some of the fitters would come and ask for a drop of hammer thinners in a plastic coffee machine cup to clean up grease and stuff. I would give them some. They only did it once.

When I worked in a 'certain' copier manufacturer's factory, we used Brasso to clean inspection flat tables. I left some in a vending cup overnight, next morning there was a big splodge of goo as if a seagull had visited!

 

[pe2dave]

Odd. I last mixed up some Shellac (in a UK plastic milk bottle) about 6 months ago. Still there.
Different plastics?

 

[niall Y]

Hmm............. , looks like styrene ( think flimsy plastic cups) might be soluble in some alcohols. so probably worth avoiding.

I have to confess I didn't heed the warning and like @pe2dave, mixed up my shellac in a plastic container, ( in my case a dog-treat, screw-top jar) And no adverse effects to report, so far

 

[Grandad455]

Many years ago, I ran a DIY store and one of the products we stocked was Rustin's wood bleach. This came as a two pack, bleach and activator. Whilst doing a stock check, I picked up a bottle of the bleach component and the bottle split, mainly down the moulding seam, and showered me with bleach. I ran out the back to the sink and dowsed my face and took my jumper off and soaked that, but the damage had already been done. Some materials react differently to others, in plastic, so err on the side of caution. Another incident, more recent, I have had some bottles of Kilrock Spirits of salts in plastic bottles and noticed that a couple of the bottles had little blisters forming on the outside. I contacted the manufacturers about it, but they never bothered to get back to me.

 

[mwinfrance]

Milk containers are HDPE, one of the more robust plastics. Plastic cups can be lots of things, some of them are polystyrene ( but not the expanded type ) they melt quickly if you look at them funny.
I discovered recently that some companies put their MEK type liquid "catalysts" into little "plastic" bottles which they can eat through in a year. Not very clever, the stuff is horribly irritant if spashed on skin , will blind if it gets in your eyes etc.I picked up the HDPE tub that I keep my polyester catalysers ( the ones in those little plastic bottles in ) half of them had melted their bottles, the tub had around 500ml of liquid "nasty" sloshing about.

It appears that some of the little bottles were not HDPE ( thick walled ) long shelf life containers, but LDPE ( thin walled ), short shelf life ****y traps.

These pages can be useful.
https://en.wikipedia.org/wiki/Recycling_codes and
https://en.wikipedia.org/wiki/Resin_identification_code

 

[throbscottle]

Reminds me of when I used to build Airfix kits. Use too much glue and it would dissolve the part! The parts being made of polystyrene of course, for gluability and rigidity.

 

[Spectric]

When you look at a car battery which has a plastic case as well as cell seperators you know that is not just any old plastic.

 

[MF1000]

Acids work in a totally different way to solvents when interacting with plastics

 

[Tom P]

Acetone, found in some nail vanish removers, and used to be the basis of celluose thinners will disolve some plastics particually styrene. Spirits of salt is the old name for hydrochloric acid HCL.
Petrol will also disolve styrene, remember at the start of the war in Ukraine they were making molotov cocktails using this method.

 

[MF1000]

Acetone & petrol are in the category of solvents …they act by breaking apart long chain molecules causing them to loose their structure. Acids work by oxidation…chemically ‘burning’ elements or compounds changing their structure.