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Midget and Sprite Technical
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Thread: Brushing or Rolling 2 pack paint
Posted 17 June 2017 at 19:55:49 UK time
MG Moneypit, Cheshire, United Kingdom

Thought I would make this a new thread as it came up in the "GN15 Leaf Green paint" thread.

I got some 2 pack (BLVC16 aka Blaze) and some activator from the local paint factors. They were a bit reluctant as they were not sure whether it was dangerous being brush painted but they did sell it to me in the end.

Things I have found out today.

1/ It is quite thin to brush so you are going to need 2 coats.
2/ As it is thin don't put as much activator in it to keep it as thick as possible. This has the advantage that it will take longer to go off.
3/ It is by far the smelliest paint I have experienced. A mask is advisable as well as good ventilation.
4/ Whatever thinning agent is used in the base paint it flashes off very quickly and from then until it goes off it will drag unless the brush is well loaded.
5/ My shell had already been stone chipped so was a very bumpy surface to paint. I needed a short haired brush and stippled it on. This had the advantage that I could put it on quite thick at panel joints.
6/ Paint the hard to reach parts first. I didn't and it is quite difficult getting right inside the transmission tunnel when other bits have been painted.

The information sheet I got with the paint said 3 parts paint, 1 part activator then 20% thinners. This is for spraying and the pot life is quoted as 6 to 8 hours. I did the 3 + 1 paint to activator ratio and it was going hard after about an hour. Luckily, I got to the end of the small amount I had mixed.
Next time I will reduce the activator ratio to 1/2 the recommended.

I only put one coat on. It's very shinny. 2 hours after starting it felt very hard. Not tacky at all.

I'm not certain how a second coat will go over a fully set first coat. I will find out tomorrow.


Posted 17 June 2017 at 21:36:40 UK time
GuyW, UK

Useful assessment Rob. Good luck with coat 2.
Like many of these jobs, in my experience one just about masters the hang of it when you get to the finish! ;-)

Posted 17 June 2017 at 22:25:54 UK time
1 Paper, Missouri, USA

I guess my question is ... WHY?

YOU can get those cheap new purple hvlp gravity paint guns for around $20 from ebay and your power mart stores here in the states harbor fraight carrys them... there basically a one to 2 time gun ... then pitch them in the trash... and they do a decent job

A compressor is dirt cheap to buy now or you can barrow one... 1000s of them around...a lot faster and a much nicer finish job


Posted 17 June 2017 at 22:36:21 UK time
John Payne, Lincolnshire, United Kingdom

Cheers Rob, useful info. My guess is that the second coat will go on fine. As its a chemical reaction that has cured it, I don't think another coat will touch it

Posted 18 June 2017 at 11:43:07 UK time
MG Moneypit, Cheshire, United Kingdom

Prop. The problem with spraying 2 pack is the mist contains iso-cyanates. If you breath them in it's a quick way to your blood stream. Cyanide in your blood is a no-no, but brushing avoids breathing in the mist so it's much safer.

Of course, you should wear gloves even if you brush it on and whatever you do - don't drink the activator!


Posted 18 June 2017 at 22:16:38 UK time
1 Paper, Missouri, USA

Well yeah.... if your creatimg a mist cloud you should always but on a mask regardless of the chemical make up.... you think smoking is bad for the lungs try a table spoon of any kind of paint into your lungs is gokng to set you back a few days... no argument there

As to the chemical make up of the paint... time vs ventialation is key, you doing a whole car your paint sounds fumy to say the least but your going to be exposed to a lower volume over a much longer period of time, allowing those chimicals to build up in heavier consentrations much slower

Its better to introduce ventilation get in and get out fast and id use a resperiator with filters designed for the chemical make up of the paint your using

Considering its a hole car id build a 1x1 wooden cage staple some 3mil clear platic over it with a box fan at one end and a home AC hvac filter at the other end a hole in the top for dprayer hose and use a resperator i discribed above and get in get it done and get out yes even wearing protective clothing

This way your exposure is minimal, no outside the wrea enviormential issues and its all contained and no dust or foreighn particals in your newly painted car and no brush /roller marks

Just because you can smell it from rolling it, dosent mean your avoiding the chemical intake... your still doing it over a much longer time. Which is far worse then instsnt hit

Think how to boil a live frog ... samething your doing by rolling it... by the time your finally feeling the effects of chemicwls being absobed into your lungs ... your screwed

Also remeber that chems volitility sometimes expands with temp and humidity

If its being forced out of a gun its expansion eill be almost instant but if a chemical is in a coffee cup its expansion can take considerably longer so it could litterly start its expansion once inside your lungs even tho it appeared invisable to you when you inhaled it.

Tjat said... you wont die from anything isaid above... its an event you will suffer thur mayne 5 times in a life time, now if you do it every day... oh yeah your dead with in a few years

Sorry for both apperance, durability and safety... i disagree with rollimg and brushing as your doing... but if we all agreed ... then that would suck...haha

Posted 18 June 2017 at 22:27:53 UK time
Mike Howlett, Strathclyde, United Kingdom

I painted my Elan with 2-pack International Yacht paint using a brush. My experience was similar to yours. It had a terrific gloss but brush marks were obvious, so I spent ages smoothing and polishing with 1500 grit wet and dry. It turned out well but was a lot of work.


Posted 18 June 2017 at 22:55:35 UK time
John Payne, Lincolnshire, United Kingdom

Mike, turned out well?! That is some understatement!!

Posted 18 June 2017 at 22:58:31 UK time
David Billington, Wiltshire, United Kingdom


My neighbour used 2 pack International yacht paint when he brush painted his miniature steam locomotive and got an excellent finish with virtually no brush marks, at least on the 2nd attempt, the first can had some sort of contaminant in it that left bits in the surface, the supplier gave him a new can FOC and that was fine. IIRC the instruction were to brush or roller the paint but not spray due to the hazard. In the end he went over the paint with fine wet and dry like your 1500 or similar to remove the gloss and give it a more appropriate finish for a working loco.

Posted 19 June 2017 at 10:09:52 UK time
P Simpson, Cumbria, United Kingdom

I wouldn't spray 2k paint without an air fed mask, ever. I know some people do.
I'm not that keen on breathing on the solvent toluene either so I generally
use the air fed mask rather than a filter mask when mixing and cleaning up as well.

Posted 19 June 2017 at 13:17:31 UK time
William Revit, Tasmania

Couldn't agree more----
Rob--Playing games with your health here
You wrote----
"3/ It is by far the smelliest paint I have experienced. A mask is advisable as well as good ventilation."
Bad news is---if you can smell it, It's going in and it's not coming back out--
You need a mask with an air supply----minimum

Posted 19 June 2017 at 15:14:36 UK time
John Payne, Lincolnshire, United Kingdom

Rob isn't spraying he's brushing. Having read the HSE recommendations I'd be happy to brush paint it, I'd probably avoid rollering though and I'd wear a decent mask to get rid of the fumes if nor well ventilated.

Here's the recommendations plus some other stuff I've found:


Posted 19 June 2017 at 15:19:02 UK time
John Payne, Lincolnshire, United Kingdom

Here's the HSE sheet:


Posted 19 June 2017 at 15:24:34 UK time
P Bentley, Surrey, United Kingdom

I have only resprayed a couple of cars and in both cases I used cellulose and achieved OK results. both times I used a new 3m face mask for each car for primer and gloss and I couldn't smell the paint whilst using it.
With cellulose, you can polish a finish from it so providing you have the right tools and time, some pretty good results are achievable by most of us.

From what I understand of Two Pack, its not only dangerous from what you will inevitably breath in, but the iso-cyanates can/are absorbed through any open cuts, grazes and also through your eyes. . . which would explain and endorse the boiler suit, full face, air fed mask get up that you see the pro's use.
Whilst I understand that excellent results can be achieved by brushing, and roller painting, (proved by the Elan picture) there is a reason why a spray gun is used, it clearly has both performance, time and cost advantages over the brush approach, but I do follow that for a home user time considerations are not always so relevant.

Posted 19 June 2017 at 16:26:06 UK time
MG Moneypit, Cheshire, United Kingdom

I should point out I have absolutely no intention of spraying 2 pack. I'm only using a brush to apply 2 pack to the underneath of the Sprite and any other hard to get at areas you wouldn't expect a professional bodywork sprayer to reach.

I intend to get the top of the car, including engine bay, inside boot area and passenger compartment of the car, as well as the exterior, sprayed by a professional.


Posted 20 June 2017 at 09:29:13 UK time
P Simpson, Cumbria, United Kingdom

Yes I understand you're brushing, it was the other comment about spraying I was referring to, which seemed a little vague about the type of mask. I've just never been confident that my filtered mask keeps everything out unlike the airfed.
I've brushed 2 pack on things without trouble, I mix it as standard. I got good results for small repairs if sanded and polished before it is rock hard.

Your approach sounds like pretty sensible use of time and resources to me.

Posted 22 June 2017 at 00:05:28 UK time
C R Huff, Kentucky, USA, zypher@aol.com

I think something has not been made clear about the non-air supplied painting masks.

The non-air-supplied masks are designed to filter out particulate (like overspray) and they are made to capture certain solvents.

The medium in the mask determines what solvents they will capture, but generally they are designed to capture volatile organic compounds (VOCs) such as toluene, xylene, mineral spirits, etc. I think that iso-cyanates are inorganic chemicals.

I don't know if it is still true today, but as of a few years ago, there was no filter medium that would capture iso-cyanates. Thus the requirement for an air-supplied respirator.

If brushing the iso-cyanate coatings is safe, that means that the iso-cyanates are not volatile. I know they are primarily supposed to react in the coating (unlike a solvent carrier that is supposed to evaporate) but I don't know if it is volatile to some degree. Rob may have investigated this, but I would check that myself if I intended to brush it without air supply.


Posted 22 June 2017 at 02:27:34 UK time
timmyk, Kent, United Kingdom

You're right about negative pressure masks they're really designed to filter out dusts, some though have carbon filters that will adsorb some organic solvents as the air passes.

Isocyanate is actually an organic chemical (it's not a solvent) and is the active ingredient in superglue. As You say, when you use 2 pack paint the isocyanate is acting as a very thin layer of glue holding all the paint particles together (that's the difference between drying as the solvents evaporate and setting as the glue binds), to me that's why 2 pack paint is hard and traditional paint feels slightly soft

The thing with isocyanate though is that it's really toxic, compared to a solvent like toluene, looking at the safety data sheets for 'tlv'- toluene is 300 ppm, isocyanate is 5ppb (m = million, b=billion) translating, isocyanate is 60,000 times more toxic than toluene. Isocyanate was the chemical at Bhopal that killed thousands

A negative pressure mask doesn't protect you enough - those things work on creating a negative pressure that pulls the air in past the carbon filter. The trouble is that unless you have a really good fit, air just leaks in without passing the carbon

the HSE has a useful data sheet at www.hse.gov.uk/mvr/bodyshop/myths/myth3.htm - sorry don't know how to make that a link so you'll need to cut and paste

I'm not being a health and safety nazi, you should all make your own decisions but be informed when you do it - don't assume negative pressure masks will protect you enough, for occasional use and not spraying (which minimises fumes) you're minimising exposure (I'd probably do that) but don't assume the mask is doing you any good


Posted 22 June 2017 at 08:18:31 UK time
Dave O'Neill 2, West Midlands, United Kingdom

Clickable link - http://www.hse.gov.uk/mvr/bodyshop/myths/myth3.htm

Posted 22 June 2017 at 09:26:21 UK time
T Mason, United Kingdom

Tim, thats interesting about the active ingredient in superglue as sometimes hospitals use a type of it to hold cuts closed rather than stitches. If it contains that I would not have thought that was a good idea. Of course it may not be exactly the same stuff but would be interesting to know.


Posted 22 June 2017 at 12:32:10 UK time
John Payne, Lincolnshire, United Kingdom

Cheers Tim, some good info there. The HSE's recommendation is pretty clear, don't spray with 2k Isocyonate without the right gear but brush application is ok (still with some precautions).
A lot of the substances I use at work are similar, the Dinitrol type stuff we use for example is ok for brushing but deadly when sprayed.

What I haven't looked into is whether spraying non isocyonate 2k without an air fed mask is ok. I've heard people say it is but personally I don't think I'll be risking it.

Posted 22 June 2017 at 12:48:06 UK time
GuyW, UK

Doesn't seem right inhaling something that then subsequently sets in your alveoli as the hardener cures it, even if the hardener itself isn't a toxic isocyanate!

Posted 24 June 2017 at 20:29:28 UK time
Flip Brühl, Netherlands

Isocyanate can give a hypersensitivity reaction and specially in persons who are genetical prone to those reactions. If there is astma eczema etc. in the family. The exposure true the skin is the most sure way to start the hypersensitivity reaction. It takes 9-10 days from first contact to allergy. If the allergy already exists it takes some seconds after exposure to get the allergic reaction, witch is seldom lethal. There is no correlation with the dose. A few molecules are enough. There is a strong correlation with the frequency that you are exposed.
If you roll or brush it always wear gloves. Even a good filter mask will not help you to prevent an allergy against isocyanate. An over pressure mask and suit will help for some time. Sooner or later you will make a fault and come in contact with the stuff. So a professional should never spray two pack unless he or she accepts the risk and works for him or herself. A sensible boss in the UK or US will never accept working with 2 pack.

(I do have two pack on my car, it it lovely, very strong, looks marvelous, is long lasting and easy to repair. After 20 years the original paint witch I
save in a metal container at low temperature is still good. And yes I am a proven allergic...)


Posted 24 June 2017 at 22:56:32 UK time
John Payne, Lincolnshire, United Kingdom

It definitely sounds dodgy stuff Flip!

If it really is that bad then why do people use it? You say that professionals shouldn't accept using it - so what do they use?! I was under the impression that it was the only thing they did use.

Certainly the painters I work with have been spraying, brushing and rolling 2k isocyonate type paints all their lives - and some of the stories they tell make you think they should be dead by now! They are always telling us how dodgy it is though.

By the way apparently even rubbing down paints with isocyonate content is dodgy - so use a mask, good ventilation and perhaps dampen things down.

Posted 25 June 2017 at 12:50:49 UK time
MG Moneypit, Cheshire, United Kingdom

Yes, I think the ISO-cyonate is a catalyst which causes the chemical reaction but doesn't change it's state. Once it hardens it is still there though locked in. If you sand it dry make sure you have a good mask and I suppose don't allow the dust to touch your skin especially if you are sweaty which you will be if rubbing down. Wet sanding should be OK as long as you wear suitable gloves.


Posted 25 June 2017 at 14:20:03 UK time
W Bretherton, South Gloucestershire, United Kingdom

This is getting worse and worse. I was just about to do a paint repair on my modern car which would involve rubbing down 2 pack (but not painting with it). I always do that bare handed to get a feel for the surface. Now I'm concerned about it.

Posted 25 June 2017 at 17:25:20 UK time
MG Moneypit, Cheshire, United Kingdom

I found this which might be useful and probably means my conjecture was wrong, after the paint is fully cured.



"Sanding down:
When isocyanate paints are fully cured, if they have been applied for more than 24 hours at room temperature or heated for one hour at 70°C, and are sanded down, the dust produced will not present an isocyanate hazard. This is because fully cured paints contain no free isocyanates. In such instances a dust mask should be worn to provide protection from the general nuisance dust present. Where new paint that may not be fully cured is sanded down, the dust will contain free isocyanates.

A particulate respirator fitted with Class H filters should be worn. Where practical, the use of wet sanding methods is recommended as a means of reducing the amount of dust generated."


Posted 25 June 2017 at 18:08:18 UK time
MG Moneypit, Cheshire, United Kingdom

So far I have brush applied almost a whole tin (1 ltr) of 2K to the bottom of the Sprite. See image.

Two coats have been applied to the whole of the bottom, one to the inside of the transmission tunnel, chassis members, steering rack support and radiator support uprights. I have applied 3 coats to one of the front wheel arches and I probably have enough left to put 3 coats in total to the other 3 wheel arches.

I'm going to get another tin to complete 2 coats where there is presently 1 coat and will probably continue with 2 coats on the foot well sides and in the battery compartment area both of which will be well hidden by other things when built up.

It is applied over stone chip. The stone chip was applied over etch primer by the previous owner.

There are no brush marks that I can see. I don't think it is my brush painting skills, more likely disguised by the dimple effect you get with stone chip.

I used 1/2 the quantity of hardener recommended for spraying. It didn't appear to go off at all in the 1 hour it usually takes to use the small quantities I mixed. It goes tacky due to solvent evaporation when applied, is dry about an hour later and full hardness overnight. It has a good shine straight from the brush.



Posted 25 June 2017 at 19:26:31 UK time
Flip Brühl, Netherlands

It looks marvelous!

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