# Casting shrinking, printing shrinkage

**URL:** <https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452>\
**Category:** Form 1/1+\
**Created:** [August 29, 2016, 7:51pm UTC](https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452 "2016-08-29T19:51:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![rocs](https://avatars.discourse-cdn.com/v4/letter/r/7ab992/32.png) [@rocs](https://forum.formlabs.com/u/rocs)\
**Post date:** [August 29, 2016, 7:51pm UTC](https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452/1 "2016-08-29T19:51:47Z")

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Hi all I have a form 1+, when people are printing in cast able resin what do you increase the size by to allowing for shrinkage when casting,

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**Author:** ![Charles\_McManus](https://avatars.discourse-cdn.com/v4/letter/c/b5e925/32.png) [@Charles\_McManus](https://forum.formlabs.com/u/Charles_McManus)\
**Post date:** [August 29, 2016, 9:05pm UTC](https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452/2 "2016-08-29T21:05:23Z")

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I find it depends on the model. All the books and online resources I’ve read say you lose about 2-3% due to shrinkage and polishing. I did some prong castings the other week to house gems 3x3mm, 5x5mm, 10x10mm and 12x12mm. I printed all prong settings at 102%, 103% and 105%, and then cast them. Just to get an idea of the amount of metal, the tree looked like this out of the hot pickler:

 ![](https://us1.discourse-cdn.com/flex025/uploads/formlabs/original/2X/8/8859860dc6bf479509f7450e27fed35ab35f3142.png)

For the smaller models, the 105% models were closer to the desired size. For the larger ones, 103%. I now do an initial cast at 104%, and then adjust for the next casting.

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**Author:** ![ChristopherBarr](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.formlabs.com/christopherbarr/32/645_2.png) [@ChristopherBarr](https://forum.formlabs.com/u/ChristopherBarr)\
**Post date:** [August 30, 2016, 12:03pm UTC](https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452/3 "2016-08-30T12:03:19Z")

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All metals have a specific shrink factor that is unique to that particular metal/alloy.  
While not addressing Silver or Gold specifically, this is a good understanding of what’s happening:

> **[Casting (metalworking) | Shrinkage](https://en.wikipedia.org/wiki/Casting_(metalworking)#Shrinkage)**
>
> There are three types of shrinkage: shrinkage of the liquid, solidification shrinkage and patternmaker's shrinkage. The shrinkage of the liquid is rarely a problem because more material is flowing into the mold behind it. Solidification shrinkage occurs because metals are less dense as a liquid than a solid, so during solidification the metal density dramatically increases. Patternmaker's shrinkage refers to the shrinkage that occurs when the material is cooled from the solidification temperature...

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**Author:** ![system](https://us1.discourse-cdn.com/flex025/uploads/formlabs/original/3X/5/b/5bc2bdf993ff27c2e0eecab5010b25626fbb327a.png) [@system](https://forum.formlabs.com/u/system)\
**Post date:** [September 14, 2016, 6:03pm UTC](https://forum.formlabs.com/t/casting-shrinking-printing-shrinkage/9452/4 "2016-09-14T18:03:20Z")

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