Object materials

Object materials is the name of a system that allows various objects to generate made of something different from their ordinary base material. It was first introduced in NetHack brass, and L later made it into a standalone patch that can be found here.

Variants that incorporate some kind of object materials include GruntHack, dNetHack, xNetHack, SpliceHack, and EvilHack; GruntHack's implementation is much different from that of L's patch, and thus different from other variant implementations.

A user has suggested improving this page or section as follows:

"All the variants that implement object materials do them slightly differently, and should be noted. Also, add a section describing what unusual properties might come from different-material objects. For example, flesh objects can be eaten."

Summary

The general purpose of the patch is to increase the variance in equipment that a player may come across in NetHack and/or its variants, as well as the strategies employed with such items. This can have diverse effects on a given game: one hero may realize too late that their gold wand of death was a valid target for an overlooked leprechaun, another may employ a pair of mithril short swords to slice their way through hordes of orcs, and still others may try to assemble an all-silver full-doby set of armor to thoroughly demon-proof themselves before entering Gehennom.

Artifacts

Artifacts, including artifact weapons, tend to have a set base material; it is sometimes possible to name or create certain artifacts such as Sting and Excalibur, with a weapon of the desired material, though whether this is allowed depends on the variant.

Monsters and object materials

In games with some form of object materials included (typically variants), monsters also have various interactions with each type of object, the more common of which are listed below.

Material hatred

Material hatred is used to refer to any particular material that deals extra damage to a certain type of monster, much like the standard interactions between werecreatures and silver (e.g. elves may have an aversion to iron weapons).

Golems

Golems that are generated randomly or via polypiling in games with object materials may death drop items made of that material among the pile of objects left in lieu of a standard "corpse".

Leprechauns

Leprechauns in games with object materials are usually given the ability to steal items made of gold as well as gold coins.

Croesus

Many variants with object materials give Croesus golden weapons and/or armor.

Object materials by variant

Below is a list of each variant's implementation of object materials.

GruntHack

Item generation

Base objects	Converts to	Probability (%)
Iron non-dwarvish weapons, weapon-tools, and armor	Iron	80
	Wood	5
	Silver	5
	Copper	3
	Mithril	3
	Gold	1
	Bone	1
	Glass	1
	Plastic	1
Wooden non-elven non-dwarvish weapons, weapon-tools, armor, chests, and large boxes	Wood	80
	Stone	10
	Iron	5
	Bone	3
	Copper	1
	Silver	1
Cloth or leather armor	Cloth	60
	Leather	33
	Paper	6
	Flesh	1
Dwarvish armor: dwarvish helms, chain mails, cloaks, and roundshields; and weapons: dwarvish spears, short swords, and mattocks	Iron	85
	Mithril	10
	Copper	2
	Silver	1
	Gold	1
	Platinum	1
Elven weapons and elven shields	Wood	80
	Copper	10
	Mithril	5
	Silver	3
	Gold	2
Elven chain mails and helms	Copper	80
	Mithril	20

Weights of different materials

When calculating an object's base weight, its weight is multiplied by a factor of current material multiplier / base object material multiplier, where the multipliers are:

Material	Multiplier
Liquid	1
Wax	1
Veggy	1
Flesh	1
Paper	1
Cloth	2
Leather	3
Wood	4
Bone	5
Dragonhide	2
Iron	12
Metal	12
Copper	10
Silver	12
Gold	14
Platinum	10
Mithril	6
Plastic	3
Glass	5
Gemstone	16
Mineral	14

Effect on AC

When calculating a piece of armor's total AC, a material bonus is calculated, which is usually current material AC - base armor material AC. If this material bonus is negative, it will decrease the base AC of the armor, to a minimum of 0. Thus, higher material AC is better. The material AC values are:

Material	Material AC
Liquid	-5
Wax	-4
Veggy	-4
Flesh	-2
Paper	-4
Cloth	-3
Leather	-2
Wood	-1
Bone	+1
Dragonhide	+5
Iron	0
Metal	0
Copper	-1
Silver	0
Gold	-2
Platinum	-1
Mithril	0
Plastic	-2
Glass	0
Gemstone	+2
Mineral	+3

Cost

When calculating the base cost of an object, the cost is multiplied by a factor of current material cost multiplier / base object material cost multiplier. The multipliers are:

Material	Multiplier
Liquid	1
Wax	1
Veggy	1
Flesh	3
Paper	2
Cloth	3
Leather	5
Wood	8
Bone	20
Dragonhide	200
Iron	10
Metal	10
Copper	10
Silver	30
Gold	30
Platinum	30
Mithril	32
Plastic	10
Glass	20
Gemstone	500
Mineral	10

xNetHack

In xNetHack, the list of eligible items is much larger compared to the original patch, and uses more complex lists of possible materials for each type of object. Certain items are renamed due to having a material-specific name; in practice, this generally takes the form of removing the material from the name (e.g. silver saber ➡ saber).

List of materials and behavior

Material	Erodeability	Effects
Glass		Always shatters when thrown, and occasionally shatters when used in melee or as armor. However, it is possible to shatterproof glass weapons and armor via the normal methods of erodeproofing, such as confused scrolls of enchant weapon. Bladed glass weapons have a +3 damage bonus. Glass helms offer metal-like protection against falling objects, but may shatter if hit by a heavy object. Glass body armor may also shatter if hit by a heavy thrown object.
Silver	Corrode	Bonus damage to werecreatures, vampires, shades, and major demons.
Gold		Blunt weapons made of these have a +2 damage bonus.
Platinum
Stone		Blunt stone weapons have a +1 damage bonus.
Plastic	Burn	Plastic weapons have a −2 damage penalty.
Paper	Burn, rot	Paper weapons have a −2 damage penalty.
Wood	Burn, rot	Wooden bladed weapons have a −1 damage penalty. Wooden helms offer metal-like protection against falling objects.
Mithril		Mithril body armor always grants at least MC2.
Bone	Burn	Can hit shades, bypassing their usual immunity to physical attacks. Positively enchanted bone armor will intercept a level drain that hits you, instead draining a point of enchantment from the armor. Bone helms offer metal-like protection against falling objects.
Iron	Rust, corrode	Bonus damage to elves, nymphs, and lesser demons.
Metal		Explicitly not iron; many items are changed to this so that elves can use them.
Copper	Corrode	Bonus damage to fungi and monsters with disease/decay attacks; copper armor can sometimes nullify falling [[Sickness|ill (stacking 20% chance with each piece of copper armor worn)
Cloth and leather	Burn, rot

List of material qualities

Below is a table that lists the density, price and AC modifiers of each material. To calculate the weight of an object, multiply its item type's weight by the density of its actual material and divide it by the density of its base material; the densities may be inexact due to deliberate changes for gameplay balance. (Assume that an object of a given material is made solidly of that material.) For example, chain mail has a base material of iron, so a set made of mithril will weigh ⁵⁰⁄₈₀ = ⁵⁄₈ as much, whereas gold chain mail will weigh 1.5 times as much.

The same is done to calculate price modifiers, e.g., a set of mithril chain mail costs ⁵⁰⁄₁₀ = 5 times as much as a regular one; note that most items made of their base material will weigh and cost the same as they did previously, i.e. the base prices and weights in the object's statblock were not changed.

For calculating object AC bonuses, subtract the base material's AC from the actual material's AC and add the result to the armor's regular AC bonus. A floor of 0 is applied, as a poor material cannot make the set of armor worse than wearing no armor at all; if the armor is metal, its floor is 1 instead. The resulting value is then effectively the new "base" as far as erosion is concerned—for instance, an iron small shield will grant 2 points of AC instead of 1, but it will go down to 0 when it gets very rusty or thoroughly rusty, instead of bottoming out at 1.

Material	Density (arbitrary)	Price (zorkmids/aum)	AC
Liquid	10	1	0
Wax	15	1	1
Vegetable	10	1	1
Flesh	10	3	3
Paper	5	2	1
Cloth	10	3	2
Leather	15	5	3
Wood	30	8	4
Bone	25	20	4
Dragonhide	20	200	10
Iron	80	10	5
Metal	70	10	5
Copper	85	10	4
Silver	90	30	5
Gold	120	60	3
Platinum	120	80	4
Mithril	50	50	6
Plastic	20	3	3
Glass	60	20	5
Gemstone	55	500	7
Mineral	70	10	6

Artifact changes

Artifacts are always made of one specific material, and some have had their default base materials changed from vanilla:

• Sunsword (iron ➡ gold)
• The Platinum Yendorian Express Card (plastic ➡ platinum)
• Sting (wood ➡ copper)
• Orcrist (wood ➡ copper)
• Stormbringer (iron ➡ metal)
• Magicbane (iron ➡ metal)

Grayswandir, Werebane, and Demonbane are all silver as usual, but the saber's base material is no longer silver by default.

Wished-for objects can only have their object material specified in wizard mode, and will otherwise have the normal base material they generate with.

Golems

Specific golems - gold, paper, leather, iron, glass, wood - may drop items made of their respective material rather than their regular drops. This has some restrictions for balance: potions, scrolls and spellbooks will never be generated from glass and paper golems, but wands are fair game.

Material hatred

In xNetHack, silver-hating code has been generalized so that it can be applied to any group of monster types for any specific material. Silver hatred itself works the exact same as it does in vanilla, with silver items dealing d20 damage to werecreatures, vampires and major demons, and silver items cannot be handled by any such monster, including by a silver-hating player.

The other materials operate according to the rules outlined below:

• Monsters making contact with an object made of their hated material take d6 damage. This is reduced to d3 for players handling such an object.
• In the player's case, the object can still be handled; due to a vanilla bug the player can always pick up an object made of a hated material with no harmful effect.
• Monsters will not wear objects that are made of a material they hate.
• If you wield something made of hated material while wearing gloves, or wear body armor made of hated material while wearing a shirt, this does not count as touching them and you will not take damage.

Elves (including elvish players), nymphs, and lesser demons hate 'cold iron', which applies to all iron in the game; this does not apply to undead variants of iron-hating monster (e.g. elf zombies). Fungi and monsters that use disease or decay attacks, including Pestilence, hate copper.

Elvish players in particular benefit from much of the above rules, which include common-sense additions to prevent too-frequent direct contact with iron. All elven weapons, including Sting and Orcrist, now have a base material of copper instead of wood; all iron items in a role's starting inventory will be made of copper for elves. Additionally, some items' base materials have been tweaked to make certain artifacts and objects in general safer for elves to handle:

• Runeswords (including Stormbringer) are now metal.
• Athames (including Magicbane) are now metal.
• All amulets, including the Eye of the Aethiopica, are now metal.
• Most rings that were iron - save for the randomized appearances "iron ring" and "steel ring" - are now metal.

Messages

The [monster] flinches at the touch of [material]!
The [material] broadsword hurts to touch!