<p>In a clear resin, which cures by light not every light particle will hit an optical active region in the resin's molecules. Especially if the layer of the resin to cure is rather thin. For a given layer thickness there's a percentage of light which will be absorbed and a percentage of this percentage will initiate the curing reactions. The more curing reactions started within a period in a given volume the faster the curing process will be finished.</p>
<p>Translucent materials contain particles which scatter incoming light. Of course the designers of a resin will choose particles which scatter that light while absorbing only a minimal share of it.</p>
<p>This will prevent the majority of photons from crossing the layer on the shortest path. This again will increase the number of initiated reactions in a given volume of resin for a constant flow of light. Of course this is some sort of tradeoff, as with too much scattering the curing speed will reduce on the distant end of the resin layer.</p>

CC BY-SA 4.0
2023-09-12T07:49:56.693Z
this is a very nice answer. In short you are saying that the UV light can easily pass through transparent resin and it can't pass as easily through opaque resin. That's probably why you wouldn't want to use pure black UV curing resins.
Hacky
CC BY-SA 4.0
2023-09-12T15:55:42.963Z
@Hacky, Both clear and translucent resins are supposedly transparent.
Aaargh Zombies
CC BY-SA 4.0
2023-09-12T06:05:23.790Z
2023-09-12T06:05:23.790Z
Ariser
<p>According to the official Elegoo resin sheet, the standard layer exposure to for clear resin is 8 seconds per layer, while the translucent resin is only 3.5 seconds.</p>
<p>For comparison, standard Gray is 2.5.</p>
<p><a href="https://drive.google.com/file/d/1_jnyMfNkm4sPJhKyN46ey5CO-ks4MRyR/view" rel="nofollow noreferrer">Official Elegoo data sheet</a></p>
<p>Both resins produce a similar effect, except one has less tendency towards yellowing.</p>
<p>Why are their exposure times so dramatically different?</p>

<resin>
Why are the exposure times for clear and translucent resins so different?
Aaargh Zombies
# Why are the exposure times for clear and translucent resins so different?

(Asked by: username_0 on 2023-09-10)

According to the official Elegoo resin sheet, the standard layer exposure to for clear resin is 8 seconds per layer, while the translucent resin is only 3.5 seconds.

For comparison, standard Gray is 2.5.

[Official Elegoo data sheet](https://drive.google.com/file/d/1_jnyMfNkm4sPJhKyN46ey5CO-ks4MRyR/view)

Both resins produce a similar effect, except one has less tendency towards yellowing.

Why are their exposure times so dramatically different?

**Tags:** resin

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## 1 answers

### Answer by username_1 on 2023-09-12. Score: 3

In a clear resin, which cures by light not every light particle will hit an optical active region in the resin's molecules. Especially if the layer of the resin to cure is rather thin. For a given layer thickness there's a percentage of light which will be absorbed and a percentage of this percentage will initiate the curing reactions. The more curing reactions started within a period in a given volume the faster the curing process will be finished.

Translucent materials contain particles which scatter incoming light. Of course the designers of a resin will choose particles which scatter that light while absorbing only a minimal share of it.

This will prevent the majority of photons from crossing the layer on the shortest path. This again will increase the number of initiated reactions in a given volume of resin for a constant flow of light. Of course this is some sort of tradeoff, as with too much scattering the curing speed will reduce on the distant end of the resin layer.

> **Comments:**
> **username_2**: this is a very nice answer. In short you are saying that the UV light can easily pass through transparent resin and it can't pass as easily through opaque resin. That's probably why you wouldn't want to use pure black UV curing resins.  
> **username_0**: @Hacky, Both clear and translucent resins are supposedly transparent.  

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