Ghostbusters Slime

Ghostbusters I
The ghostbusters films are almost synomous with slime, with plenty of occurances in both the films, including Peter Venkman (Bill Murray)'s infamous quote "He slimed me", voted in the top 100 movies quotes of all time (1).

The first film introduces us to a team of 4 parapsychologists who team up to start a ghost catching business when they find major paranormal activity threatening the city. We get introduced to slimer, a friendly ghost, who as his name suggests is very slimy...

Slimer is a costume based ghost, with some animatronics to give movement and facial expressions. He is acompanied by the trademark slime, based on 'Methocel' a Methylcellulose ether derivative (2).

slimer  Slime Application
Slimer and Slime Application

We also meet the giant Stay Puft Marshmallow man, 'marshmallow' engulfs Walter Peck the EPA guy late in the film. This effects shot was achieved with 200lbs (90kg) of shaving cream released from a large bag hanging from a crane (2).

Marshmallow Man 1  Marshmallow Man 2
Marshmallow Man  Marshmallow Man

Ghostbusters II
Ghostbusters II was significantly more slime filled than original, particularly due to the now famous river of slime that is central to the story, as it threatens to engulf the city of New York. Variously known as Psychomagnotheric Slime, Mood Slime and Psycho-Reactive Slime it reacts to emotions, both positive and negative. Primarily pink in the film, It has been portrayed in other colours in the animated series (4).

Stuart Fink, a project manager for GB2 has been quoted that an estimated 100,000 gallons were made, 40,000 of them in the museum scene (5).

As would be expected, a lot of effort was put into both the river of slime and the other ectoplasmic ooze effects in the film, with the team led by the effects supervisor, Chuck Gasper. The basis of the slime was hydroxypropyl-methylcellulose, branded Methocel, and coloured with a food colouring. There were a number of variations between scenes, as Chuck Gasper, speaks about in Cinefex (3);

"The usual formula to create thirty-two gallons of slime, was about eight cups of methocel to four-and-a-half cups of separan. Then we would add about fifty cc's of red food coloring and thirty-two gallons of water. You could actually eat the stuff. It would not have any taste, but you could eat it. The grade of methocel used is also used in pie thickeners and salad dressings."

These quantities therefore equate to the following proportions, by volume:

Methocel= 1.6%
Separan= 0.9%
Food colour= 0.04%

The separan is a "non-ionic polyacrylamide", normally used as a flocculent in water treatment, however it would appear that this grade is no longer in production (certainly under this trade name). It is this that creates the stringiness clearly seen in some of the shots- for more info on this type of material see the main slime page.

As such large quantaties of slime were needed, it was mixed offsite by Blair Adhesives in 1500 gallon batches and tankered to set. Converley it was disposed of by collection by suction truck.

The good news however is that a variant of polyacrylamide is available as 'Sticky Yuck in the US; Sticky Yuck or as 'Slime Baff' or 'Slime Play' in the UK; Slime Play 

I have succeeded in making a very passable version of the slime using 1.5% Natrosol (as I haven't got any methocel, and it gives a clearer goo than guar or xanthan gums) mixed with the slime play polyacrylamide.

The river as seen in the film was shot in miniature and composited with live action shots against a partial set of the subway steps and a matte painting of the rest of the tunnel. The river trough was approx. 1ft wide by 10ft long, on a slight slope fed by a high level dump tank with the slime recirculated back to the tank with a pump.

The specific colourings and visual look of the river took a significant amount of effort and changes to produce; the colour mix has not been revealed but the ooze contained a mica pearliser to give a shimmering effect and had a layer of clear mineral oil on the surface. The river had various air bladders and other methods of affecting the flow with puppetry used to produce further movement and tentacle effects when needed.

Ghostbusters River of Slime  Ghostbusters River of Slime
The River of Slime from Ghostbusters II  

Ghostbusters R 

Now the Ghostbusters reboot has launched, more pictures, behind the scenes videos and interviews have started to appear, giving us a much greater insight into the effects in the film. Slime still forms a central tenet of the film, much in the same way as the original.

Prior to the film a few snippets of infor leaked out, particularly notable is the fact that the slime effects are at practical, and not CGI. Paul Feig, the director tweeted an image of the slime being used in June 2015 (6.). It looks fairly close to that used in the previous movies.

Paul Feig Slime  Ghostbusters
Tweeted Slime Image & Slimes Tested

The question "what is the Ghostbusters slime made of?" will be a big question for many people, and is unlikely to be definitively answered for some time as it is a 'trade secret' of the film. We can however have a good stab at working out the recipe from the info available, and indeed I am pretty confident that it is in reality quite close to the first two films.

Firstly, it has been reported in a GQ article (7) that tapioca flour forms part of the recipe- I believe that it is unlikely this made it's way through to the final film as starch based thickeners, of which tapioca flour is type (d) usually require boiling to work as a thickener. This is not really practical for on-set manufacture, and as stills from the video (9) show, the slime is mixed from dry powders with water without boiling. The three cups at the rear right of the test slimes photo above are labelled with a number and 'AR'- these suggest to me a starch, likely the tapioca and a 'mesh size', a measure of the size of the powder.

Also in the image is container marked ultraslime, this is clearly the commercial product produced by Ultramaterials.
Most of the images end in a code 2Y1G- I strongly suspect that this refers to 2 Yellow 1 Green, proportions of colouring to be used.

It can be seen from the images the below that the final slime is stringy. This cannot be achieved by using a standard thickener alone, and so must be an additive. In the earlier films, this was seperan, but as this is no longer available I suspect it to be another brand of the same material, a polyacrylamide.

The thickener that adds bulk to the slime is likely to also similar- my suspicion is that this is Sodium Carboxy Methyl cellulose (Sodium CMC), although at present this is unconfirmed.

The colouring used looks to be a flourescent yellow/green kids poster (tempera) paint used in a relatively low concentrations, as can be seen from the image of the mixing, coupled with the transparency of the slime in the screen shots.

In the screen shots from the behind the scenes video we can also find out a couple of interesting bits of other info;
Some of the effects of the slime can be seen to be enhanced by lighting from below, illuminating the the slime.
Slime is sprayed in a number of cases; It can be seen that a fire nozzle is connected to the end of the hose and in some cases a remotely controlled valve is used to turn slime on or off.
The slime looks to be fired from a pressurised tank- you can see effects crew filling a tank in one of the stills that looks like an air over fluid pressure tank.
A standard 'shop vac' is used for cleaning up the slime.

If you want to make your own slime, I would use the following as a close recipe. Please see my gunge page LINK for full details on mixing and using your slime.

1.5% Sodium Carboxy Methyl Cellulose- from chemical suppliers, ebay etc.
1% Polyacrylamide- "Slime Play" in the UK or "Sticky Yuck" in the USA
Dry blend (mix) the ingredients before mixing into water
Warm water
Flourescent green and yellow poster paint (tempera) to colour to your desired colour

I can supply Sodium CMC and Polyacrylamide within the UK if you need to make a lot of slime.

Ghostbusters Slime  Ghostbusters SlimeGhostbusters Slime
Kristen Wiig slimed on set of Ghostbusters
Slime appears to be pumped through a fire nozzle and contolled by an electric or air controlled valve.

Ghostbusters Slime
Stringiness of the slime

Ghostbusters Slime  Ghostbusters Slime
Ghostbusters Slime  Ghostbusters slime
Slime being mixed- Note the colourant & the powder being mixed in

Ghostbusters Slime  Ghostbusters Slime
The slime lit from below

Gostbusters Slime  Ghostbusters Slime
Tank being filled and then used

Note: Methocel is a brand name used by Dow for a range of thickeners, not just methylcellulose, so if you hear this quoted it is not sufficient to determine the actual thickener. Just to complicate things further, it has also become somewhat a generic term for thickeners, so is difficult to rely on any source that quotes just 'Methocel'.

(2). Making Ghostbusters. Don Shay. New York Zoetrope. ISBN 0-918432-68-5
(3). Cinefex 40. Don Shay. Nov 1989.
(5). Ghostbusters Gets Gross With Slimy Effects, The Cincinnati Enquirer Saturday, June 24, 1989 Section D, Julie Hinds

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(c) M. Pantrey 2015-16