Double poured collodion, to cover a hole and so it was still sensitized. The previous hole remains visible

Gap in emulsion due to poor collodion pouring technique.

You may get gaps in your collodion layer due to the collodion breaking up and sliding off the plate. You will need to dilute your collodion mixture slightly as it will have lost too many solvents in evaporation. Another possibility is that the plates you are using are not clean enough.

‘Crepe-lines’ caused by uneven coating of collodion onto the plate. This can be remedied by using proper pouring techniques (keep rocking the plate, don’t go too fast or slow). It may also be that your collodion is too thin by an excess of alcohol / ether.

Collodion flaking / cracking/ peeling off the plate when still wet or when drying

Your plates are either not clean enough or you are using the wrong type of glass (pre-cut glass sometimes comes with an easy-clean coating that will prevent the collodion from sticking to it). Try subbing the edges with albumen before pouring, a different cleaning routine or a different image carrier.

Alternatively, the problem could be the elasticity of your collodion. You will need to use the 4% USP one – the plain collodion. If you suspect it’s a chemical issue, you can try diluting your mixture carefully (don’t cause air bubbles in the mix!) with a bit of alcohol.

Silver bath stopping lines. These lines are caused by not inserting your plate into the silver bath in one fluid motion

When a white speck doesn’t have a tail it’s called a ‘pinhole’, and is caused by dust or debris settling on the plate after sensitizing, but before development. It gets in the way for the developer to reach that tiny part of the plate, causing non-development. Make sure your plate holder and work environment are as clean as possible and carry the plateholder around wet-side-down.

When a white speck has a tail, it’s called a ‘comet’ and is caused by debris sitting on the plate before or during sensitizing. To aid this, sun and filter the silver bath, using a funnel and a cotton ball. To filter the collodion, you can use a cotton ball drenched in alcohol. This specific hailstorm of comets was caused by Hypo fixer, some of which ended up in the silver bath. Never mix up your funnels!

The plate looks normal when developed and fixed, but (expanding) black spots appear onto the plate after 1-2 days. This issue can be resolved by a longer final rinsing of your plate(s) *Image kindly supplied by Paul Roman*

White ‘blobs’, usually at the edge of an image, sometimes creeping all the way in, are called ‘oysters’ because they resemble them in shape. They are caused by contamination of your plate holder, which is easily fixed by cleaning the plateholder with a bit of distilled water or alcohol. The oysters on the plate cannot be rubbed off without damaging the collodion layer – but some people like having them as it adds to the character of the plate.

Developing lines, in a wave pattern as the plate was rocked sideways. Either cut the developer with distilled water to make it less active, or make sure to develop in a more even layer – perhaps even use a helpers tray.

A second pouring of developer has eaten a small part of the image away

Overdeveloped, and fogged.

Fogging is often caused by a light leak, over exposure or over development, but can also be caused by your developer. Overexposure – fogging – can not be rubbed off the plate but if the issue is a chemical one – we call it scumming as it can be wiped off the plate. If you have a fogged over plate, try rubbing some of it off to narrow down your quest for the underlying issue.

Overexposure and light leaks are easily fixed with timers, gaffer tape etc. An overexposed plate that you think will remain too bright after varnishing can be reduced somewhat by using diluted Farmer’s Reducer on the plate before any varnish is applied.

Overdevelopment will produce a more silvery image with ‘grain’ to it. Apart from that, it lacks contrast and will appear fogged. Running a wet cotton ball over the plate sometimes removes a bit of that, but might leave some streaks if you are not careful and the image will never be as contrasty as a properly exposed one.

Lack of contrast should not be confused for fogging. Your collodion might be too fresh, so it hasn’t got that amount of contrast yet. Your developer might be too old – developer loses it’s contrast over time. Your developer might be overactive, which you can remedy by adding a reducer (acid, sugar) or cut it with distilled water
Another possibility could be that you left your plate in the silver bath for too long, any time over 3-4 minutes will create a significant reduction in contrast.

Solorization of the image, caused by over development. Take the image again, exposing longer and developing shorter.

Developer can get overactive in warm weather (develop shorter or add acid) and slower in the cold (develop longer)

Yellowing or browning of the emulsion after development, and not being cleared by fixing, possibly caused by organic pollution in tap water

These water drops can look rather attractive when positioned well, but are caused either by developer splashes, or not rinsing the plate well enough after development and before fixing

Fogging, caused by light leaks, or uneven development

A single lighter streak or spot on your plates indicates a light leak in your darkroom, tent, camera or plateholder. Find it and kill it with a little black paint or tape

Black spot in the middle of your image. The colodion may have slid off and the area has not been sensitized.

Your developer may not have reached this part of the plate, leaving this part blank. If you find your developer not covering your plate well, like a greasiness or repulsion, try adding a little alcohol to your developer. Add it in increments, till the flow gets back to normal. Adding too much alcohol will severely darken the image.

Alternatively, put your silver bath through maintenance; Estabrooke’s “The Ferrotype and How to Make It”:”When new silver is used for coating the plate, the developer requires no alcohol, but as every plate which is immersed in the silver solution imparts to it a portion of ether and alcohol from the collodion film, the silver bath soon acquires enough to change somewhat the character of the sensitized surface, giving it the power to repel the developing solution. By the addition of alcohol to the developing solution the repelling power is overcome.”

Finally, your developer may have hit the plate too hard and washed off the silver. Develop in a smooth motion from the side of the plate

Dark specks caused by the silver bath, ‘transparent spots’. These can have a number of causes, according to Towler’s ‘The Silver Sunbeam’:

– undissolved particles of the iodides in the ether and alcohol of the collodion; this is particularly the case with iodide of potassium in anhydrous alcohol; these afterward become dissolved in the subsequent operations. The remedy is a drop or two of water, or of diluted alcohol, or of bromide of ammonium.

– particles of dust in the camera or of the insoluble iodide of silver in the bath, adhering to the surface of the collodion, produce specks, both opaque and transparent. The remedy is to keep the camera and the room free from dust, if the bath is the cause, the trouble may be avoided by keeping the plate in motion during sensitization.

– a crystalline deposit of iodo-nitrate of silver, which, as the bath becomes weaker, is precipitated in a crystalline form on the surface of the collodion film. This form of deposit occurs with an old bath. Its remedy is to precipitate it out of the bath by adding water, and then by filtration. Then for every ounce of water thus added pour in after filtration the same amount of a nitrate of silver solution to take its place.

– When the bath is the cause of transparent spots, a small quantity of a solution of chloride of sodium (common salt) thrown in is found to be of great benefit. Chloride of silver and nitrate of soda are formed by double decomposition; the insoluble chloride probably carries down with it the dust or particles which are the cause of the trouble, or the nitrate of soda dissolves them.

in this case, due to the spots not being fully transparent, the plate must have been put in motion once or twice during sensitizing.

Transparent spots, see the previous image with a similar problem. This plate has been kept quite still and the spots are fully transparent.

The white drops are probably water droplets that dried onto the plate, causing a less than perfect finish. Remedy by rinsing the plate with distilled water instead of tap water before drying.

A scuff mark from another plate / object bumping into the collodion layer after development but before drying.

Underexposed and overdeveloped

Overexposure – and movement due to long exposure times.

Provide your model with a rest of some sort to prevent movement as much as possible. Cut back on exposure and development times.

Should fogging/ contrast problems persist, try adding more glacial acetic acid or alternatively, sugar, to your developer. The Acetic Acid renders the development uniform, by restraining the violent action of the iron and enabling it to combine more readily with the film; it has also an effect in whitening the image and increasing its brightness.

Possible double pouring of developer, eating some of the image away

Insufficient washing after development, before fixing *image kindly supplied by Simon Harbord*

Those ‘cabbage’ lines are caused by insufficient washing after development, before fixing

Movement in the image – your model didn’t sit still enough or your camera slipped / moved. Provide models with supports or – in this case – some additional heat source to stop them from shivering!

There is also streaking on the plate. The plate was inserted into the silver bath too quickly after pouring the collodion layer.

Streaking on your plate – these are caused by inserting your plate too quickly into your silver bath after pouring the collodion. The ether and alcohol are not done out gassing, which prevent proper osmosis in the silver bath.

Blueness to the image (it can be much brighter blue than this – like a cyan blue) – caused by under development

The image is weak and grey. Your silver bath may not be strong enough (Is your silver bath old? Are there any blacks in the image?) or you may have overexposed the image (There may be some blacks visible, but the image overall is greyish /white).

The varnish was poured too slow, not using enough varnish

Bad pour, too slow to move around the plate. The plate and/ or the varnish were not warm enough.

Bad pour, sloppy enough to let the varnish bottle *drip* onto the middle of the plate. Plate and/ or varnish not warm enough to make it less obvious

My Varnish is eating away my image

Try diluting the varnish with some water, around 2-3% to start. Make sure the alcohol you are using for your collodion is the same kind as you are using for your varnish and that the varnish you are using is not too old. Always try to varnish your plates as soon as they are dry to prevent trapping dust or other chemical imbalance issues.




…If I shake it before use?
It cause the insoluble iodides to stir up and cause havoc on your plate. You’ll get holes, pinholes, comets and uneven coverage due to air bubbles

…If I use it straight after mixing it?
Collodion increases in contrast but it’s speed decreases over time. You’ll get fast-non-contrasty plates, which may look fogged over grey. Leave your mix to ripen for a few days / weeks.

…If I don’t pour it well on my plate?
You’ll have gaps, no biggie.

…If I don’t wick off the pouring corner?
You’ll get a yellow build-up line along the ridge of your plate. Worst case is some of it falls into your silver bath, contaminating the bath and interfering with your next plate(s)

…If I put it in silver too quickly?
Some of the collodion might come away, contaminating the silver bath. Worst case, the layer peels off.

…If I put it in silver too slowly?
The collodion will have dried and not take up the silver. You’ll have a plate that will not be sensitized and not be able to take a photo. It’s called wet plate for a reason.

…If I spill some?
If it’s a smooth surface, just wipe it off like the jelly it is. You can also leave it to dry so it flakes off. Try alcohol on other surfaces (rugs etc)

…If I dilute my collodion mix with alcohol or ether when it becomes too thick?
The collodion layer will become blueish and the resulting mix will produce a very thin film. The plates need to be extra clean to prevent staining from the silver and small circular patches of blue and green stains of uneven development can occur.

…If I used Isopropyl alcohol (rubbing alcohol) instead of denatured alcohol?
Well, I tried this and it does work if you’re in a pinch. The resulting collodion film seems to lose solvent super quick and the plate start drying out faster than normal. There is a higher chance of the emulsion layer lifting and / or cracking. The image seems similar with only slight loss of contrast.


…If I leave it in light?
Nothing. It might get a bit of a sunning when left in bright light, but it won’t go off or anything. UNLESS you are using a silver bath mixture containing alcohol and nitric acid, exposure to light will result in foggy plates.

…If I don’t sun my silver bath?
With use, the silver bath will become contaminated with iodides and you may see the results of that on your plate (pinholes etc).

…If I store it in plastic?
Nothing, storing in plastic is recommended as the bottle won’t shatter when dropped. The silver won’t eat it away although it may stain a little on the sides/ labels.

…If I store it in glass?
Nothing, as long as you are a 100% you’ll never EVER drop that bottle. Not only is silver expensive, it stains like crazy.

…If I spill some on the table/floor/camera?
Silver stains can be removed with household ammonia or a solution of potassium cyanide. Needless to say you should never be using silver in any space you eat!!

…If I spill some on myself?
Silver stains can be removed with household ammonia (NEVER use this near you mouth, nose, ears, eyes or any broken skin), but they will wear off naturally in a number of days. If you get silver nitrate in your eyes it can blind you, so be careful!

…If my silver bath is too weak?
A weak silver bath is not recommended for positives. (20 grains/ 1 ounce water (= 44 grams per liter)) You’ll get a weak, greyish image.

…If my silver nitrate bath is too strong?
Some texts recommend a strong bath for advanced users (40 grains of silver nitrate to 1 ounce of water (=88 grams per liter)), it will shorten your exposure times in-camera and give a brilliancy to the image. As it will have larger amounts of Nitric Acid, you must strengthen the developer accordingly otherwise the latent image will not come through. The danger of a strong bath is the increased risk of stains at the edges of the plate and metallic spangles in the shadow areas.

A higher concentration of nitrate of silver relative to a weaker presence of sulphate of iron in the developer results in great contrast and bold deposits of silver. If your image has become too bold and doesn’t yield enough detail in the half-tone areas, you can try scattering a LARGE quantity of developer over the plate surface to wash away a portion of the free nitrate of silver.

A reduced concentration of nitrate of silver relative to a strong presence of sulphate of iron in the developer leads to slower development, softer half-tones or in worst case the highlight won’t be opaque.


…If I do not rinse my plate after developing?
The developer will continue its work and should you take your plate into any light source before fixing, it’ll result in streaky lighter lines across your plate. Apart from that, the undiluted developer will mess up your fixer quite quickly, rendering it useless.

…If I rinse my plate with tap water instead of distilled water?
Tap water will have organic matter floating around in it, alongside a whole host of other chemicals. Personally I always rinse with tap water since I use so much of it and have seen no ill effects – but please do not use it for any of the other mixes. The organic pollution may result in yellowing or browning of your image, and it reacts to silver nitrate by making the bath quite milky.

…If I dunk my plate in a water bath instead of flowing water over the surface?
Nothing spectacular. I find I use less water this way by using one dunk bath for a few plates before replacing it with a fresh one. Do be careful if you think your collodion layer may release or break up.


…If I leave my plate to fix for too long?
You’ll start losing detail in the mid-tone areas. Recommended fixing times are usually: until the plate is fully cleared x2

…If I don’t fix long enough?
Your image will change over time with exposure to light, depending on how short the fixing time was.

…If I use old fixer?
It will be less potent and most likely contaminated by previous plates, which could cause a whole host of issues. Best case scenario is that your image is slower to clear, but left in the solution long enough, will still be properly fixed. Worst case is that fixing results are uneven and unreliable.

…If I don’t fix my plate?
It’ll disappear! Don’t do it!!

…If I use Hypo instead of Cyanide of Potassium?
According to my antique reference books, Hypo contains sulfur, which is the somewhat unstable element that will cause a darkening of your image surface. Cyanide of Potassium will always produce a whiter image. I personally like using hypo because it’s a little safer in a collection of flammable, toxic substances.


…If I don’t give my plates a final wash?
The fixer on your plate will wreak havoc on your plate, even in the short run. With hypo, you may get spots. With Cyanide of potassium, your image will fade away

… If I don’t have the time or enough water to wash my plates straight after shooting them?
Think of a construct to keep your plates safe and wet until you get a chance to wash them. It may not be advisable to leave them in a tub for days, but a few hours won’t hurt them. I use a film plate washer from the 1940s, it fits the size of my plates perfectly in the vertical slots. It holds 6 plates, enough for a short trip. Hypo fixes will need much more water in a much longer wash than Cyanide of potassium, where a few swirls of fresh water can already do the trick.

… If I wash my plates for too long?
Nothing, they’ll be wet longer

….If I don’t wash my plates long enough?
If your fixer remains residual on your plate, it will damage them in the long run. Hypo results in darker spots, cyanide of potassium will fade your image.

….If I wash my plates in super cold water?
Nothing, they will be washed.

….If I wash my plates in super hot water?
This actually happened to me, but lucky for me I shot those plates on metal. It does seem my plates lost some of their contrast. Had they been on glass, they would have most likely slid off and be ruined.


…If my collodion starts peeling / cracking?
It is most likely that either your plate wasn’t clean enough, or your collodion was too ‘thin’ (i.e. contained too much alcohol / ether). Try subbing the edges with albumen or thicken your collodion a little with fresh, unmixed collodion. Be aware that this is a patch and your collodion may give your some trouble until that mix is finished.

…If dust settles on my plate?
You can either rinse the plate again if it’s still quite wet, or carefully use some canned air after it’s fully dried. Resist the urge to brush it off with a finger, brush or cloth as you may damage the fragile surface of your plate.

…If my plate lightens after its dried?
Plates sometimes appear darker and a little more contrasty when they are wet – an easy remedy is using a varnish. If your plate has now fallen flat, you may wish to re-shoot using a shorter exposure time.


…If my varnishing is super sloppy and I want to try again?
There are techniques to remove your varnish without damaging your image surface. I personally have not tried any of these and I would sincerely recommend getting it right in one go. Use a few of your tester plates to try your varnish viscosity and pour before going for the best ones.

…If the varnish eats my image away?
Try diluting the varnish with some water, around 2-3% to start. Make sure the alcohol you are using for your collodion is the same kind as you are using for your varnish and that the varnish you are using is not too old. Always try to varnish your plates as soon as they are dry to prevent trapping dust or other chemical imbalance issues.

…If I use a ‘non-traditional’ varnish, like store-bought car spray paint or acrylic varnish?
These have been tried by various other wet-platers, with good results. The archival properties are at this stage yet unknown. Some varnishes may be expected to yellow, crack or peel after a few decades. There are a few photographers currently developing their own varnish mixes and offering them up for sale, if you wanted to try something different.

… If I don’t varnish my images?
It’s easy to damage an unvarnished photo if you’re not careful, so it’s always recommended to varnish any image you wish to keep.


…If I wanted to re-use a plate.
Please do! It’s easy to do with glass (soak in very hot water, with a drip of washing up liquid) but near impossible to do with metal plates. Cleaning them will damage the black layer resulting in greys in your shadow areas. Only do this if you plan on re-blacking them somehow.

…If I wanted to use old window glass.
Please do! It’s how I got started, by cutting down massive marked down panes of window glass. Do mind that you do not get the kind with the special UV coating as collodion does not adhere well to it.

…If I wanted to use plastic, or bottle caps, or stones.
Please do! You’ll soon find out what works for you. Photographers around the world have successfully used a wide variety of surfaces to shoot images onto. If you can coat it and sensitize it, you can photograph onto it. Be careful about losing ‘bits’ in your silver bath though!