<h2>Resin basics</h2>
<p>Resins are tricky, but probably <a href="https://3dprinting.stackexchange.com/a/6941/8884">less tricky than FDM</a> as the manufacturing process is much less likely to include contaminants in the shape of contaminated air, particles, or adding lead into the print. This is all due to the whole process of creating the polymer happening under the protection of the resin, which in its monomeric liquid state is so toxic that it is unlikely any bacteria can survive in it. But before going out on a spending spree, you need to be aware that there are basically 3 kinds of resins on the market, only one of them is for SLA. To know exactly what you get you'd need to read the MSDS, which is usually available by the manufacturer of the resin.</p>
<ul>
<li>Two-component resins as you found in the lower half of the question. You might know them as Epoxy or Polyurethane resins. They have a base material and a hardener, sometimes called Component A and B. If mixed <em>perfectly</em>, they cure fully, neither hardener nor resin remains. This means it is chemically inert.</li>
<li>Air-curing resins. These two come as Polyurethanes and also Acrylates and you might know them better under the terms paint, lacquer or coating.</li>
<li>Light-cured resins, as you find them in SLA resins and all coatings that are not air-curing. These are for SLA a strange chemical mixture of a photoinitiator and then some monomers that create a copolymer while coatings can be as easy as having some initiators and the rest is a single type of monomer.</li>
</ul>
<h2>Food safety?</h2>
<p>There are some resins is on <a href="http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=177" rel="nofollow noreferrer">the list of FDA approved plastics</a> for food contact. The list is exclusive: if your plastic doesn't fit one of the listed ones, you can not use it. One example would be <a href="https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=177.1555" rel="nofollow noreferrer">polyacrylate</a>, which is defined as being &quot;formed by melt polycondensation of bisphenol-A with diphenylisophthalate and diphenylterephthalate&quot; - which excludes any other method of getting a polyacrylate and it prescribes exactly what basic materials are allowed.</p>
<p>As a result, many two-component resins and light-cured resins that don't match the exact chemistry and method to create an approved plastic/coating will not match the FDA approval list and won't get approval <em>on their own</em>.</p>
<h2>Coating</h2>
<p>But there is often a way out by applying a proper coating, for example with a sufficiently thick food-grade <a href="https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=177.1680" rel="nofollow noreferrer">Polyurethane coating</a> for dry foods. This would render the item <em>food safe</em> under FDA standards for the approved appication. You'd need to adhere to the proper method to apply this coating (manufacturers add those to the labeling usually), which can at times be somewhat complicated.</p>
<h2>Insert</h2>
<p>Another way might be to add an insert that does follow FDA standards, for example, a steel cup for liquids.</p>

CC BY-SA 4.0
2020-08-21T18:11:56.903Z
Even the polyurethane coating is for "dry food only" though. There are various levels of food grade. I found a silicone spray on the web, but it's food grade in the sense that it's "intended for incidental contact with machinery that touches food".  It's a bad bottleneck for innovation in the space.
K Mmmm
CC BY-SA 4.0
2020-08-21T21:56:06.180Z
Woha, thank you so much for such a detailed answer! I guess we'll have to wait then until 3d printers can make food safe prints.
Unapedra
CC BY-SA 4.0
2020-08-21T13:00:28.077Z
2020-08-21T18:33:36.510Z
2020-08-21T18:33:36.510Z
Trish
<p>I've actually read that resin printed parts are not food-safe in <a href="https://www.reddit.com/r/3Dprinting/comments/7h834s/how_safe_is_cured_sla_resin_for_indirect_food/" rel="noreferrer">Reddit</a> and <a href="https://formlabs.com/blog/guide-to-food-safe-3d-printing/" rel="noreferrer">Formlabs guide</a>. However, it also says that <strong>food-safe can be achieved applying some kind of food-safe coat</strong> to the printed parts, or even <strong>printing with ceramic resin</strong>.</p>
<p>As an owner of a Elegoo Mars Pro, I've searched for the second - <strong>ceramic resin - and I've found nothing</strong>, so I guess it's only suited for more expensive and professional printers.</p>
<p>But regarding the food-safe coatings, is there any recommendation on <strong>which and how to apply them</strong> for resin printed objects? Is there any other way to achieve food-safe resin printed parts? Maybe are there food-safe resins, even though they may be more expensive (I haven't been able to find any)?</p>
<p>The scenarios I think that have to be considered are four:</p>
<ul>
<li>Prints to be used for <strong>liquids</strong>: like mugs and coffee cups, or recipients to hold drinks in the fridge, for example.</li>
<li>Prints to be used for <strong>solids</strong>: just recipients to put dried fruits, nuts, olives...</li>
<li>Prints to be used while eating, which some <strong>tools</strong> <strong>may interact</strong> with: plates, bowls, which will be in contact with knifes, forks, and some other material that could scratch it.</li>
<li>Prints to be <strong>in contact with the mouth</strong>: this would be maybe a mix of the other, but would include forks, spoons, mugs...</li>
</ul>
<p>I guess that the cleaning and maintenance will depend on the process to make them food-safe.</p>
<hr />
<p>I've been searching for the net, and I've found these kind of epoxy resins. I see people use them and say it's food-safe, but I cannot see it stated anywhere. Maybe are those what I'm looking for? Maybe not because some of them are for wood (maybe they can be used in other suraces, too?)? Some samples:</p>
<ul>
<li><a href="https://www.amazon.es/disponibles-Fantasy-TRANSPARENTE-perfecto-bicomponente/dp/B07L78WZ9Z/ref=sr_1_3?__mk_es_ES=%C3%85M%C3%85%C5%BD%C3%95%C3%91&amp;dchild=1&amp;keywords=resina%20epoxi%20comida&amp;qid=1598011018&amp;s=tools&amp;sr=1-3" rel="noreferrer">Fantasy craft</a></li>
<li><a href="https://www.artresin.com/pages/artresin-europe" rel="noreferrer">Art Resin</a></li>
<li><a href="https://www.amazon.es/componentes-Cristal-Transparente-laminar-adhesivo/dp/B07S2WDMNB/ref=sr_1_1_sspa?__mk_es_ES=%C3%85M%C3%85%C5%BD%C3%95%C3%91&amp;dchild=1&amp;keywords=resina%20epoxi%20comida&amp;qid=1598011018&amp;s=tools&amp;sr=1-1-spons&amp;psc=1&amp;spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUUc0WFpFUVlRQlE1JmVuY3J5cHRlZElkPUEwMDMyNTUwMjRHUDJGTEE3NUFXWCZlbmNyeXB0ZWRBZElkPUEwNzc1MzEyMk82TUpWU00yS1JRWiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=" rel="noreferrer">Dipoxy resin</a></li>
</ul>
<p>Hope to find a little bit of knowledge to increase safety when printing some parts and being careful about the different applications that our prints may have.</p>
<p>Thank you!</p>

CC BY-SA 4.0
2020-08-20T08:54:04.933Z
are you asking *certified food safe*?
Trish
CC BY-SA 4.0
2020-08-20T10:56:22.437Z
Not exactly. I just want not to end up sick if I drink coffee from a mug printed with resin. I guess that the best would be *certified food safe*, but I'm not going to commercialize. Just being sure that I won't end up sick and it's safe to be used by all family members (children and so on included) is enough. And if I have to clean it by hand, it's ok too.
Unapedra
CC BY-SA 4.0
2020-08-21T12:36:08.087Z
Dipoxy Resin is a typical 2-component casting resin. if mixed properly, it cures through and goes inert. Same for Art Resin and Fantasy Craft. Though, these are not SLA/DLP resins.
Trish
CC BY-SA 4.0
2020-08-21T21:57:08.650Z
Yeah, they are not SLA resins, but covering the already SLA printed piece with these, wouldn't make that print food safe?
Unapedra
CC BY-SA 4.0
2020-08-21T22:02:17.070Z
not if the resin is not food safe, and as I pointed out below, most cast-resins are not. *silicone* however is available in food safe.
Trish
CC BY-SA 4.0
2021-10-05T09:49:23.403Z
Porcelite is a ceramic resin which can be cooked in a kiln at 1300 °C to obtain a 95% solid resin part. Not cheap.
FarO
<sla><safety><resin><food>
SLA printers: food-safe resin parts
Unapedra
# SLA printers: food-safe resin parts

(Asked by: username_0 on 2020-08-20)

I've actually read that resin printed parts are not food-safe in [Reddit](https://www.reddit.com/r/3Dprinting/comments/7h834s/how_safe_is_cured_sla_resin_for_indirect_food/) and [Formlabs guide](https://formlabs.com/blog/guide-to-food-safe-3d-printing/). However, it also says that **food-safe can be achieved applying some kind of food-safe coat** to the printed parts, or even **printing with ceramic resin**.

As an owner of a Elegoo Mars Pro, I've searched for the second - **ceramic resin - and I've found nothing**, so I guess it's only suited for more expensive and professional printers.

But regarding the food-safe coatings, is there any recommendation on **which and how to apply them** for resin printed objects? Is there any other way to achieve food-safe resin printed parts? Maybe are there food-safe resins, even though they may be more expensive (I haven't been able to find any)?

The scenarios I think that have to be considered are four:

* Prints to be used for **liquids**: like mugs and coffee cups, or recipients to hold drinks in the fridge, for example.
* Prints to be used for **solids**: just recipients to put dried fruits, nuts, olives...
* Prints to be used while eating, which some **tools** **may interact** with: plates, bowls, which will be in contact with knifes, forks, and some other material that could scratch it.
* Prints to be **in contact with the mouth**: this would be maybe a mix of the other, but would include forks, spoons, mugs...

I guess that the cleaning and maintenance will depend on the process to make them food-safe.

---

I've been searching for the net, and I've found these kind of epoxy resins. I see people use them and say it's food-safe, but I cannot see it stated anywhere. Maybe are those what I'm looking for? Maybe not because some of them are for wood (maybe they can be used in other suraces, too?)? Some samples:

* [Fantasy craft](https://www.amazon.es/disponibles-Fantasy-TRANSPARENTE-perfecto-bicomponente/dp/B07L78WZ9Z/ref=sr_1_3?__mk_es_ES=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=resina%20epoxi%20comida&qid=1598011018&s=tools&sr=1-3)
* [Art Resin](https://www.artresin.com/pages/artresin-europe)
* [Dipoxy resin](https://www.amazon.es/componentes-Cristal-Transparente-laminar-adhesivo/dp/B07S2WDMNB/ref=sr_1_1_sspa?__mk_es_ES=%C3%85M%C3%85%C5%BD%C3%95%C3%91&dchild=1&keywords=resina%20epoxi%20comida&qid=1598011018&s=tools&sr=1-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExUUc0WFpFUVlRQlE1JmVuY3J5cHRlZElkPUEwMDMyNTUwMjRHUDJGTEE3NUFXWCZlbmNyeXB0ZWRBZElkPUEwNzc1MzEyMk82TUpWU00yS1JRWiZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=)

Hope to find a little bit of knowledge to increase safety when printing some parts and being careful about the different applications that our prints may have.

Thank you!

**Tags:** sla, safety, resin, food

> **Comments:**
> **username_1**: are you asking *certified food safe*?  
> **username_0**: Not exactly. I just want not to end up sick if I drink coffee from a mug printed with resin. I guess that the best would be *certified food safe*, but I'm not going to commercialize. Just being sure that I won't end up sick and it's safe to be used by all family members (children and so on included) is enough. And if I have to clean it by hand, it's ok too.  
> **username_1**: Dipoxy Resin is a typical 2-component casting resin. if mixed properly, it cures through and goes inert. Same for Art Resin and Fantasy Craft. Though, these are not SLA/DLP resins.  
> **username_0**: Yeah, they are not SLA resins, but covering the already SLA printed piece with these, wouldn't make that print food safe?  
> **username_1**: not if the resin is not food safe, and as I pointed out below, most cast-resins are not. *silicone* however is available in food safe.  
> **username_2**: Porcelite is a ceramic resin which can be cooked in a kiln at 1300 °C to obtain a 95% solid resin part. Not cheap.  

---

## 1 answers

### Answer by username_1 on 2020-08-21. Score: 5 | Accepted answer

## Resin basics

Resins are tricky, but probably [less tricky than FDM](https://3dprinting.stackexchange.com/a/6941/8884) as the manufacturing process is much less likely to include contaminants in the shape of contaminated air, particles, or adding lead into the print. This is all due to the whole process of creating the polymer happening under the protection of the resin, which in its monomeric liquid state is so toxic that it is unlikely any bacteria can survive in it. But before going out on a spending spree, you need to be aware that there are basically 3 kinds of resins on the market, only one of them is for SLA. To know exactly what you get you'd need to read the MSDS, which is usually available by the manufacturer of the resin.

* Two-component resins as you found in the lower half of the question. You might know them as Epoxy or Polyurethane resins. They have a base material and a hardener, sometimes called Component A and B. If mixed *perfectly*, they cure fully, neither hardener nor resin remains. This means it is chemically inert.
* Air-curing resins. These two come as Polyurethanes and also Acrylates and you might know them better under the terms paint, lacquer or coating.
* Light-cured resins, as you find them in SLA resins and all coatings that are not air-curing. These are for SLA a strange chemical mixture of a photoinitiator and then some monomers that create a copolymer while coatings can be as easy as having some initiators and the rest is a single type of monomer.

## Food safety?

There are some resins is on [the list of FDA approved plastics](http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?CFRPart=177) for food contact. The list is exclusive: if your plastic doesn't fit one of the listed ones, you can not use it. One example would be [polyacrylate](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=177.1555), which is defined as being "formed by melt polycondensation of bisphenol-A with diphenylisophthalate and diphenylterephthalate" - which excludes any other method of getting a polyacrylate and it prescribes exactly what basic materials are allowed.

As a result, many two-component resins and light-cured resins that don't match the exact chemistry and method to create an approved plastic/coating will not match the FDA approval list and won't get approval *on their own*.

## Coating

But there is often a way out by applying a proper coating, for example with a sufficiently thick food-grade [Polyurethane coating](https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=177.1680) for dry foods. This would render the item *food safe* under FDA standards for the approved appication. You'd need to adhere to the proper method to apply this coating (manufacturers add those to the labeling usually), which can at times be somewhat complicated.

## Insert

Another way might be to add an insert that does follow FDA standards, for example, a steel cup for liquids.

> **Comments:**
> **username_3**: Even the polyurethane coating is for "dry food only" though. There are various levels of food grade. I found a silicone spray on the web, but it's food grade in the sense that it's "intended for incidental contact with machinery that touches food".  It's a bad bottleneck for innovation in the space.  
> **username_0**: Woha, thank you so much for such a detailed answer! I guess we'll have to wait then until 3d printers can make food safe prints.  

---

