"Two-Pack or not Two-Pack ?"

That is the question, posed by Tommy Sandham, who examines the use of two-pack paints, boldly going where few others have gone before!

This article should appear shortly in the MK1 Cortina Owner's Club magazine and is © Tommy Sandham.

Iíve spent many hours during the last 18 months spraying (or attempting to spray) two-pack paint. Iíd like to highlight some of the problems Iíve encountered along the way in the hope that it will answer some of the questions you may have about two-pack paint.

Firstly, two-pack paint is dangerous to your health (depending on who you talk to, depends on HOW dangerous). There does seem to be a distinct lack of hard facts around. Many car restoration web-sites say its dangerous, but donít give any data to back up their statements. One says it is illegal for the amateur to spray two-pack. I sense they are repeating what they have heard so that they arenít left with any responsibility.

Two-pack paints contain Isocyanates, which is toxic, and can build up in the bloodstream with prolonged use, causing death.

I discovered early on that the minimum safety equipment I needed to buy was an air-fed visor. This provides a higher air pressure inside the mask than out, so keeps hazardous fumes out of your air supply. Remember to site the compressor AWAY from the spraying process otherwise the compressor will suck in the contaminated air and feed it back through your mask!

An air-fed mask and regulator is essential if you decide to spray two-pack paints.

Letís start again, this time at the beginning. I have had a 1964 Cortina 1500 Super in the garage for over 18 years. I drove it for about three years, then it was laid-up in 1986 due to the work needed. I made a list of jobs when I laid it up and this was invaluable when I came back to work on the car.

Having completed a lot of the mechanical tasks, my thoughts turned to paint. The car was original, being finished in blue with a white roof. Having replaced a lot of panels, the only panels in sound, original condition were the roof and the boot-lid. I have painted another MK1 with Cellulose, having attended a paint spraying course at the local college. The results were at the time quite acceptable, but over the last six or seven years the paintwork has deteriorated very badly. I decided to look at using two-pack for the blue car. I searched the internet but did not find much useful information. I then got in touch with a paint supplier who ultimately supplied all my paint, materials and much helpful advice.

It seems that only certain people are allowed to sell Cellulose paints now, but Iím still not totally sure of the legality of selling two-pack to an "amateur," that is, a non-professional sprayer without an approved spray-booth. I believe it to be quite legal, but all the "experts" frown on it. Maybe its legal to sell it, but illegal to use it? If you spray for yourself, as a hobby it is probably okay. However if you spray for someone else and receive payment, you are no longer an amateur and become subject to all sorts of Health and Safety legislation.

I bought 5 litres of the main colour, identified by my first "expert" as Aqua Blue. It turned out to be Ultra Blue, which is one shade (?) tone (?) different to Aqua Blue but is not listed as a Ford colour. It was matched from a sample so I must now live with it.!!!. It looks correct. The roof was white and this was guessed to be Cirrus White. I was able to give the paint supplier a sample of the blue from a piece of scrap bodywork, but could not do the same with the roof. I bought 1 litre of white. When this paint is mixed in the ratio 2 parts paint to 1 part activator plus 10% special thinners, you get lots more "material" to apply.

I phoned Machinemart's help line to enquire about their air-fed visor. They told me (quite correctly) that my Tiger 15/60 compressor would drive the mask successfully. What they did NOT tell me, and at the time I did not know to ask, was that the compressor would not drive the visor AND the spray gun at the same time.

I finished all the bodywork in the engine bay (learning lead-loading in the process). I then primed the bay with non-isocyanate two-pack etch primer. I used Super Etch Primer which gives a high build, a nice finish, and little trouble.

Two shots showing the front end of the car and engine bay in two-pack primer.

I then connected a Y-piece to the air line and tried spraying the engine bay with two-pack colour, with me wearing the air-fed visor. The results seemed ok, but the indicator on the mask showed a very low air pressure. I successfully sprayed the engine bay, which involved very short bursts of spraying. When I then tried the boot lid, the finish was dreadful, all Orange Peel, and the visor showed no pressure.

Two photos of the engine bay sprayed in two-pack top coat. The result is very "shiny" and initially looks a little bit un-natural.

I then discovered that the Tiger 15/60 compressor was not man enough for the job. I subsequently bought an old second-hand 1 horse-power compressor for £60. This thing looks like 1950s kit. It was so heavy we had to dismantle it to get it into the back of my estate car. Two of us could not lift it! The air compressor part alone you could hardly lift single-handed! That same compressor pump toppled -over during the journey home and deposited lots of smelly old oil on carpets in the back of my nice modern motor!

Re-assembled and working at home it lasted a few days then broke down. My neighbour (an electrician) was convinced that the motor had burnt out. Luckily, I found that there is a large starter capacitor and one of the electrical connections to this had broken. A simple solder job and we were off again.

My "new" 1950s compressor, weighing slightly more than a 10-tonne truck, is now used to power the air-fed mask.

So, the second-hand compressor was given the job of driving the spray-gun and the Tiger 15/60 the air-fed visor. Results got worse after that. Orange peel on every panel. This then involved rubbing down to primer and spraying again. Some panels I have done 3 or more times to get right. I reckon Iíve sprayed the entire car and would have had material left over, from 2.5 litres of paint.

This is scary! The belly comes with the T-shirt, it's not mine (honestly - would I lie?). Me, modelling the air-fed mask, showing the regulator/filter on the belt and the coupling to the airline/compressor.

After taking advice from the next "expert" I was advised that the standard set-up on my spray-gun, ideal for Cellulose, was no good for two-pack. Iíd have to spend £106 to convert my ten-year-old £140 DeVillbiss JGA gun. Not an attractive option. I then consulted my paint supplier who said heíd been using the standard set-up for years and I should just turn the air pressure up. This then aggravated the air supply problem as the second hand compressor could not cope with the extra demands made of it. The compressor broke down again twice, but luckily each problem was easily fixed.

I next tried spraying the front wings and got little rings in the paint; I believe its called cissing. I was convinced this was caused by the activator absorbing moisture, having lost one tin completely with the activator going solid. I consulted another "expert" who agreed with my diagnosis and said the activator was notorious for absorbing moisture and causing problems in the finished paint job.

Going back to my paint supplier, he said no, the problem is oil or silicone on the panels. Apparently WD40 is a paint killer, you never get it off panels. It could also have been oil used to lubricate my air-sanders. I even stripped one wing (the drivers' side) back to bare metal, carefully panel-wiped the surface, primed and sprayed again. Same problem. I needed to add a small amount of anti-silicone additive to allow the paint to flow round the oil or silicone. This additive costs around £10.

UPDATE: April 2005. The worst problem was on the drivers' side wing. Then, by a strange chain of events, I was told that if you were using silicone brake fluid it causes all sorts of strange paint problems!! Of course, I had used silicone brake fluid. Strange that the paint problem only appeared on the side where you top up the brake fluid!!!!

I next did some tests on my compressors and decided the Tiger 15/60 was best for the spray gun while the second-hand one was adequate for the visor. Maybe you saw that coming, but it wasnít so obvious to me! I now have about 15 seconds spraying time before the compressor kicks in and struggles to keep up with the spray-gun.

I had to move the second-hand compressor into the garage for the Winter as the rain was ultimately going to cause the electrics serious harm. Note that the compressor supplying your air-fed visor MUST be sited away from contaminated air otherwise you will poison yourself even quicker!

I bought the parts to convert my spray-gun but only noticed a small difference. The problem lies in the compressor(s).

I have now completed the spraying; there are a few problems, it is not perfect, but then neither are my cars, so I am having to live with it. Surprisingly the white roof turned out much better than I expected. I polished it with 1000 grit (which two-pack hardly notices) and am very pleased with the outcome. Iíll be 56 this year and suddenly I have started to feel my age due to a few health problems, so Iíll have to settle for what Iíve done.

It doesn't look too bad from this angle. If you have the book, "Restoring Small Fords" you will see the same car (on the front cover) from 18 years ago, before renovation! My son, David, helped to push the car out of the garage. The engine is another story...!!!

Iíve created the following table to highlight each problem Iíve found, together with MY solution.





Purchasing Two-pack materials

Paint manufacturers are very "coy" about who they will sell to. Try two or three suppliers and I bet you find one who will sell to you.

Iím using Churchill Paint which I am very happy with. I wonít name my supplier.

You need primer, two-pack paint, activator/hardener and special thinners.


Quantities required

Two-pack goes on thicker, with fewer layers required. See Technique, below.

It also mixes 2:1 with the activator so 3 litres of "paint" will give over 6 litres of material and should do a Cortina MK1 with plenty to spare.

Get advice from the paint supplier.


Two-pack is toxic

Two-pack paints contain Isocyanates, toxic substances, which can build up in the bloodstream with prolonged use causing death.

You MUST have an air-fed visor and wear protective clothing, including protective (latex) gloves.


Air consumption

Iíve been advised that "published" compressor ratings are always a bit generous. So a machine rated at 15 cubic feet/minute may well NOT give you this output constantly.

Err on the side of caution. You need a much bigger compressor than you think (we are talking three-phase electricity here, not something the average home workshop has). (Iím using two compressors now, and theyíre still not really enough). You could hire a second one for about £60 a week.

Air fed visor

The absolute minimum safety requirement is an air-fed safety visor. This will require 8-9 cubic feet/minute of clean air.

Donít even think of trying to spray two-pack without this. See Risk Assessment, below. There may be an alternative Ė a mask fed from a compressed air cylinder. Ask at a Hire shop.

Update: see http://www.paint-spray-safety.co.uk/

Thanks to Paul Ferguson
MD of Supreme Visors!!

Other safety equipment

Isocyanates can be absorbed through the skin and eyes. You need surgical /latex or plastic gloves and preferably a one-piece protective suit.

Donít mess with this stuff!

Spray Gun

I used a DeVilbiss JGA which is now 10 years old. I paid £140 for mine, but have seen them second-hand from £15 upwards. Try Ebay.

Find out the air consumption for your gun. This is important. The JGA requires 10 cubic feet per minute.

Add the requirements of the gun and the visor to get the required compressor rating, plus a bit spare. Iíve been trying to get 19 cubic feet per minute from a compressor rated at 15.

Spray Gun Set Up

My gun has a 30 air cap, 1.8 fluid tip and D-EX needle which should be the standard Cellulose set-up when you buy this gun

Iím reliably informed by DeVilbiss that the "correct" set-up for two-pack on a DeVilbiss JGA is a 186 air cap @ £48, FW703 fluid tip @ £33 and an FF needle @£8.

Donít take my word. Check this for yourself.

Mixing the paint

When you open the paint there is a VERY strong vapour. In future I am going to wear the air-fed mask when mixing.

My paint mixes 2:1: plus 10%, which means 2 parts paint, one part activator, plus 10% special thinners. You need clean plastic containers to mix the paint in, and a reliable way of measuring the quantities.

Hardener/activator problems

You MUST keep the tin air-tight and you should use it within six months otherwise it eventually goes solid in the tin.

The paint seems to keep without problem as long as the tin is shut properly.

Spray technique

Forget any Cellulose techniques you may have learned. Air pressure should be 75 psi at the regulator (which is about 65psi at the gun on a 15 metre air line). Spray on one thin/mist coat. Wait ten minutes then spray one heavier coat. FINISHED!

Iíve put three or four coats on some panels when I didnít need to!

Two-pack not so worried about damp as Cellulose + will work down to 5įC.


Dealing with runs

Use a guide coat (I use black from a spray can) to lightly mist over runs or sags. Sand with 240 or 360 wet and dry paper used wet, using a sanding block until all the guide coat is gone. Runs should now be gone too.

Runs were not as common with two-pack, although I did have a few because of my bad technique. If you donít use a sanding block you WILL get tram lines on the panel from the ends of your fingers pressing onto the paper.


Dealing with Orange Peel

Sand down smooth, try again.

Try turning the fluid adjustment DOWN to reduce fluid flow through the gun. You need as much air as possible, so when that is turned up to maximum, reduce fluid.




The finish is very glossy and does not require polishing.


Risk Assessment

Do not spray two-pack until you can satisfy the following minimum safety requirements:-

1) Donít spray if you live in a housing estate, or with other properties close by. There is a risk of causing health damage to neighbours, children or pets, such as ornamental fish ponds!

2) Donít spray in a closed garage. Youíre going to have to spray with the doors open, plus any windows or back doors open too.

3) Donít spray unless you have a proper air-fed visor and a compressor man-enough to drive it.

4) I advise you to spray one panel at a time, to minimise the amount of vapour released into the atmosphere. Hopefully, this will spread your spraying activities over several days or weeks.






I live in a detached bungalow, in the country, with a high, thick hedge between me and the next house.



I have a "standard" brick garage with "up-and-over" door. There is a back door which is left open too.



I have a Machinemart-supplied air-fed mask and dedicated compressor.

I have had to use two compressors.

Note: Professionals would want to spray the car in one go.

Gun cleaning

You clean the gun etc with standard Cellulose thinners.

Donít let it harden-off in the gun or pot. Itís a *** to clean up once set.

To sum up. Was it worth it? Yes, to me, I think so. The finish is VERY glossy when first sprayed, so much so that it does not look "real". However it fades a little, if that is the right word, over a few months and now looks quite natural. If it lasts better than Cellulose it will have been worth it.

Would I do it again? On balance, yes. It caused me a lot of extra time, trouble, expense and a lot of frustration. But I now know what to do!!

Would I recommend it to others? No. Thereís too many "ifs, buts and maybeís" and I still donít know if it is legal. Then thereís the problem of compressors. You really need a very LARGE compressor, bigger than you are going to find in the average home workshop. One that will work with Cellulose will NOT provide enough output for a spray-gun and air-fed mark. You MUST NOT spray without the correct air-fed mask.

What we need, from someone better qualified than me, is an assessment of the newer painting systems available (such as water-based paints) to see if they are suitable for home use, versus the traditional Cellulose, which may now be difficult to buy, and two-pack. Two-pack was an interesting diversion for me, but it is certainly NOT for everyone and should be treated with a great deal of care and respect.

I believe within a few years you will not be able to spray a car at home with any paint system. The powers that be will have tightened-up the sale of materials so much you will have to go to a professional, and they aint cheap.

If you can add anything helpful, please either email me or write in and tell the Club. But please don't ask me any questions -- all I know is already here!! Thanks.

Page last modified:- 19 May, 2006

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