paint thinner

[AJH]

Is there any reason petrol or diesel should not be used to thin the hammerite smooth I am painting my gate with?

[newshound]

If you try it, I suspect you will see why it is not advisable.

[Max Demian]

I suppose petrol is too volatile and diesel not volatile enough, for a start.

[tabbypurr]

Petrol is fast evporating, nasty stuff to breathe in, and creates clouds & trails of vapour that's not only flammable but explosive and likes to move flame along its path back to the user. Other than that...

Diesel takes forever to evaporate, not suitable for use in paint unless you can tolerate extreme drying times. Paraffin does gradually evaporate and would be a lot more sensible. 28 second heating oil is much the same thing.

Veg oils don't evaporate but do polymerise to make a tough coating. when I tried coating with olive oil it took most of a year to set, so can't recommend that either.

NT

[newshound]

Traditional domestic gloss paints used a hydrocarbon thinner (white spirit) although turpentine also works (the chemistry of that is complicated).

Hammerite thinners included hydrocarbons and ketones and some ester. It used to be the case that the paint would separate if you just used a pure hydrocarbon. But I'm pretty sure they have changed the formulation so maybe hydrocarbons will work now.

One good reason for not using petrol or diesel might be the tax. Maybe modern biodiesel with 10% or more of fatty acid methyl esters will be better, or maybe not.

It's trivial to try it with a small quantity. All sorts of idiots post on Usenet :-)

[AJH]

I was more worried about its effect on paint longevity. First result from using petrol is that it dries matt so it must change something. Hammerite say only to use their thinners and the coshh sheet gives the ingredients as

Hydrocarbons, C9-C11, n-alkanes, isoalkanes, cyclics, < 2% aromatics

and in there apparently included

Cyclohexanone and n-butyl acetate

as I don't want to do the job again I'll order some and another can of paint.

[Brian Gaff (Sofa 2)]

Very flammable vapour and discolouration. Brian

[Brian Gaff (Sofa 2)]

Yes the latter is hardly a thinner, more of a thicker! Brian

[Peter Parry]

It makes it awfully lumpy. The real thinner is Xylene. Lots of sellers on eBay.

[michael adams]

Three reasons.

a) If neither are suitable there's no knowing how long it may take, from say 2 minutes, to 2 months, to 2 years to find this out the hard way.

b) If neither are suitable it will mean a lot of faffing about removing all traces of the resulting mess, before starting all over again.

c) Given petrol or diesel are presumably that much cheaper than the recommended thinners if they actually worked then this information would probably already be all over the Internet and you wouldn't be needing to ask.

michael adams

...

[Martin Brown]

Unleaded petrol has enough benzene in it (<1% just) that you really shouldn't be allowed to sell it to the general public. It is about 25% aromatics. That means that it might work as a Hammerite thinner provided that you didn't use very much of it. It might work even better if you allowed the most volatile alkane fraction to evaporate off first.

If there is any source of ignition about expect a Darwin award.

Hammerite do sell thinner and brush cleaner for their new formulations (which are not as good as the old maximum aromatic VOC toxic stuff). ISTR it is mostly xylene with a few additives.

I presume in the lockdown era you don't fancy queueing at B&Q to buy some - when I went past this morning the queueing time looked like several hours and the carpark was as busy as on a normal business day!

Try Wilko - their queues are much shorter...

[AJH]

Thanks I'll add to ebay's fortunes and wait, no hurry besides I don't fancy my chances if I do get corvid19 before hospitals have their act together.

[harry]

The solvent used in hammerite is ketone. (Also used to clean the brushes.) That's the reason for the distinctive smell. Some shops sell brush cleaner for hammeraite (ketone) which can be used to thin it also. If you use anything else it makes a hell of a mess.

[tabbypurr]

Being pecked to death by crows is a terrible thing :) Sow air spell chuckers.