---
title: Bulk Mixing Considerations
slug: process/bulk-mixing-considerations
description: Optimize your DLS printing process with our comprehensive guide on bulk resin mixing failure modes. This document highlights essential best practices for achieving uniform mixing and managing crystallization and salt formation.
docTags:
createdAt: 2024-07-04T01:16:44.967Z
---
# Failure Modes
## Resin is not mixed at the correct ratio
Improper resin ratios may lead to issues with both print quality and material properties. Specifics depend on the resin and how imbalanced the ratio is, but can result in **decreased accuracy** (increase in cure-thru and overcure ) and **decreased toughness or stiffness. **
- In general, stay within **± 1.5%** of target component amounts for best results.
- **EPU-family durability **is more sensitive to imbalanced mixes.
- **EPX-family accuracy **is more sensitive to imbalanced mixes. However, unless the offset accuracies would be quite small (10s of microns) unless the imbalance was greater than 5%.
## Resin is not mixed thoroughly or uniformly
**Thorough, uniform mixing is important for best results.** One way to evaluate mix quality is by addition of a **fluorescent dye,** but this is only for establishing a thorough mixing protocol through visual inspection. **Resin mixed with dye cannot be used for printing. **
- Testing should match actual mixing conditions (container, resin volume, mix time) as closely as possible.
- Once tested, this protocol can be used moving forward, and eliminates resin waste due to burn off from cartridges.
## Testing workflow
- Incorporate 0.1 wt% of Fluorescent Brightener 184 into Part B
- CAS: 7128-64-5, available through Sigma-Aldrich
- Mix using desired method.
- Visualize with 365 nm light source (search “365nm UV flashlight”)
- Below are examples of incomplete and complete mixing:
::::VerticalSplit{layout="middle"}
:::VerticalSplitItem
**Incomplete mix**** - **Swirl pattern indicates components are not fully blended together.
:::
:::VerticalSplitItem
**Complete mix**** - **Absence of patterns shows components are properly blended into a uniform whole.
:::
::::
# Bubbles
Vigorous mixing may lead to the formation of **bubbles **in the mixed resin.
Bubbles are typically displaced from the layer of resin that is being cured during the print process. However, in extreme cases, these bubbles may be in/on the printed part and lead to mechanical or aesthetic defects.
- **Surface defects** are likely geometry specific and are most noticeable on **cassette-facing flat surfaces.**
- Extreme mixing conditions and bubble formation may lead to **pigment separation** which will affect printability and part aesthetics.
::::VerticalSplit{layout="middle"}
:::VerticalSplitItem
:::
:::VerticalSplitItem
:::
::::
# Spraying/Splashing
When using an **overhead mixer,** high mixing speeds or mixing smaller amounts of resin may result in splashing.
- To mitigate spraying or splashing, **start mixing at low-speed** and be wary of splashing of Part B.
- Please refer to [SDSs](https://www.carbon3d.com/stewardship) for specific hazards and warnings.
# Salting
With repeated opening and closing of the stock container,** the Part B component **can form a **salt.** Small amounts of salt may be present in mixed resin and are acceptable for printing because the salts decompose during baking.
**Large amounts of salts** can result in incorrect ratios so proceed with caution.
If you have questions about salts in Part B, reach out to [Carbon Support](mailto\:support@carbon3d.com).
**Acceptable Levels of Salt**
::::VerticalSplit{layout="middle"}
:::VerticalSplitItem
:::
:::VerticalSplitItem
:::
::::
**Unacceptable Levels of Salt**
::Image[]{src="https://api.archbee.com/api/optimize/3CesIL2dYMCHPZvRjp8S0/G_m7ywO_SEsmrAnyXr2ia_image.png" size="50" width="610" height="615" position="flex-start" caption="Substantial amount of salt crystals." alt="Substantial amount of salt crystals." showCaption="true"}
We suggest **downpacking **into smaller containers to minimize the chances of salting. Remember, **Part B **components must be stored in UV light-resistant containers, such as **opaque amber nalgenes.**
# L1 Tips & Tricks
::::VerticalSplit{layout="middle"}
:::VerticalSplitItem
- The L1 cassette weighs **at least 45 lbs. ** Always use the [L1 Cassette Cart](docId\:iBV6gVPWquTiQ9FUSb89_) to maneuver the cassette when not in the printer.
- Two additional lab consumable accessories are recommended when printing with an L1 printer.
- **Wide spatula**
- For checking the window between prints.
- For removing leftover resin.
- **Resin transfer container**
- Optionally for dispensing.
- When using a scale to measure dispensed resin.
- For removing unused resin.
- Can be disposed of after use (in solid hazardous waste).
:::
:::VerticalSplitItem
::Image[]{src="https://api.archbee.com/api/optimize/3CesIL2dYMCHPZvRjp8S0/M7yeQ8u8cGPbt2fd4FWFW_image.png" size="82" width="1680" height="2726" position="center" caption="Wide spatulas and transfer container" alt="Wide spatulas and transfer container" showCaption="true"}
:::
::::
- Note that **one full cartridge** is the **minimum** amount of resin needed in the cassette, to cover the window, throughout a print.
- Leftover resin can be transferred to an M Series printer, if available, when there is enough pot life left for the resin.
- Expect more time for dispensing than with an M Series printer.
- Multiple dispensers or an MMD are recommended to save time.
- See [Accessories & Supplies](docId:95TwE3ttL-5ihI6dNl4XI) to purchase the items referenced above.