Rubber to Gold

"Converts all Bloons partially into gold, getting more cash per pop from affected Bloons."

- In-game description

 is the fourth upgrade of Path 3 for the Alchemist. It allows the Alchemist to throw potions that partially turn bloons and MOAB-class bloons (except the BAD) into gold. Bloons partially turned into gold provide +200% more cash per pop.

It costs $2,335 on Easy, $2,750 on Medium, $2,970 on Hard, and $3,300 on Impoppable.

Description
Rubber to Gold will add an extra attack that turns bloons partially into gold. Affected bloons will appear slightly golden; these bloons will earn +200% cash per layer popped. Its special attack comes out every 5 seconds and can hit up to 15 bloons. The gold effect lasts indefinitely and soaks through layers (but not for MOAB-Class).

Attacks that can penetrate multiple blimps or can instakill them will consider all popped layers as if they were partially gold.

Rubber to Gold also retains its Lead to Gold special capability, whereby popping lead bloons with this Alchemist in any way will give an instant $50 (not affected by other income modifiers or round pop income penalty). Leads can still be affected by Rubber to Gold; when they are affected by Rubber to Gold, popping them will earn +200% pop income, but cannot affect the Lead to Gold bonus.

The Rubber to Gold Alchemist will now dress up as an early English alchemist. Additionally, his goggles and eyes both become golden in appearance. The artwork features that alchemist revealing a golden-looking liquid potion.

With the Path 1 crosspaths, Larger Potions adds a large backpack on the monkey's back, while Acidic Mixture Dip adds a bucket of acid on the right-hand side of the monkey's backpack. With Path 2 crosspaths, Stronger Acid changes the acid in the bottle to purple and gives the Alchemist white gloves, while the Perishing Potions upgrade gives it a black facemask and black gloves.

Summary
Rubber to Gold is a fraction of the cost of Monkey Town, a similar income-per-pop tower, but relies on attacks and proper positioning to maximize income. When utilized properly, it is a very efficient income source, possibly even more than Banana Farms in some cases. To maximize its total income, including its Lead to Gold benefit, the other defenses should be based mostly on slowing down the bloons, instakilling blimps, and avoiding lead-popping power outside of the alchemist as much as possible. Maps with bends or curves benefit the income production of Rubber to Gold a great deal, but maps with multiple entries may decrease potential for Rubber to Gold farming.

Tips

 * Place the alchemist at the front or midsection of the track, in order to affect as many bloons and layers as possible.
 * Setting the alchemist to strong will make it target the bloons that provide the most cash, since the effect soaks through all layers. It will make the best profit on Ceramics, as they take many hits to destroy, and the Rubber to Gold effect capitalizes on their high health pool.
 * The Acid Pools set up by the Alchemist will not apply gold.
 * On the other hand, Acid Pools will still reward $50 if a Lead Bloon goes over it, due to Lead to Gold.
 * MOAB-class bloons that are affected by Rubber to Gold give +200% income when hooked in by Monkey Pirates or Pirate Lord. Likewise, trapping an affected MOAB-class bloon into an XXXL Trap will provide +200% income once full, on top of a +100% bonus, for a total of +300%.
 * Towers that can help to clump up and/or slow down bloons are an effective complement as they increase the amount of bloons affected by each hit of the Rubber to Gold potion.
 * Glue Hose has excellent coverage making it one of the more effective choices for this role. As a bonus, it does not pop bloons (or pops them very slowly with Corrosive Glue), allowing Rubber to Gold to apply its effect to more layers. Relentless Glue crosspathed with Glue Soak is another good choice, with the bonus of slowing down MOABs.
 * Likewise, the Bloon Sabotage ability is a decent option, however it is global and will immediately slow all bloons upon activation, thus losing some of the clumping value of Glue Hose.
 * Arctic Wind can be used to clump up bloons, especially Ceramics, but comes at the cost of dealing some damage to nearby bloons. The 1-3-0 Arctic Wind is usually the more useful crosspath for this purpose.
 * Knockback can be used to slow progress of Ceramics, but it deals quite a lot of damage to normal bloons. Place it away from the beginning of the alchemist's range and use it as a general cleanup tower after Rubber to Gold is applied to bloons. It is also wise to set the Super Monkey on Strong so that it does not kill off any bloons entirely. 0-3-2 Robo Monkey set on Strong and Close or a 0-2-3 Dark Knight set on Strong are probably the best options for this purpose.
 * The best crosspath for Rubber to Gold is 1-0-4. 0-2-4 is stronger at offense, but it loses out on potential income gain through a larger splash radius for its goldify attacks. 2-0-4 is weaker because it can potentially cause nearby towers to pop Lead before the Alchemist has a chance to use the Lead to Gold effect.
 * When optimized, Rubber to Gold income generation in a full game gains between +150% and +200% more income, equivalent to affecting between 75% and 100% of the bloons in the game with Rubber to Gold's gold status effect. The maximum income bonus is +200%, which would require every popped bloon to be partially golden.
 * Contrary to popular belief, Rubber to Gold does not provide 3x income, but rather +200% income. This is not mathematically equivalent, as the mechanics of combining multiple income per pop sources stack additively by percentage increase rather than multiplicatively by a set number. Rather, the income bonus percentage increase is the same no matter what other income per pop sources are utilized, such as Monkey Town or Bloon Trap. Thrive likely also counts too.

Sounds
When converting bloons into gold:
 * [golden bling sound]
 * [golden bling sound]
 * [golden bling sound]
 * [golden bling sound]
 * [golden bling sound]

Trivia

 * Despite the fact that Ceramic Bloons are made of clay, they can still be turned into gold.
 * After update 3.0, this also applies to M.O.A.B. Class Bloons (except the BAD).
 * Even though Version 19.0 added a separate money counter for almost all towers, it has not been yet implemented for Lead to Gold, Rubber to Gold, Monkey Town (and by extent Monkey City), Pirate Lord, Support Chinook, and Jungle's Bounty. It has yet to be fully implemented for Spirit of the Forest (ability only), and Sun Temple and True Sun God / Avatar of the Vengeful Monkey with Support sacrifices.
 * On Medium Difficulty, it takes 1800 RBE worth of goldified bloons, excluding multi-HP layers, to break-even the cost of a single 0-0-4 Rubber to Gold.