# Flash on plate around raft

**URL:** <https://forum.formlabs.com/t/flash-on-plate-around-raft/22892>\
**Category:** Support & Troubleshooting\
**Created:** [April 3, 2019, 12:59am UTC](https://forum.formlabs.com/t/flash-on-plate-around-raft/22892 "2019-04-03T00:59:39Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![MorseDentalLab](https://avatars.discourse-cdn.com/v4/letter/m/f05b48/32.png) [@MorseDentalLab](https://forum.formlabs.com/u/MorseDentalLab)\
**Post date:** [April 3, 2019, 12:59am UTC](https://forum.formlabs.com/t/flash-on-plate-around-raft/22892/1 "2019-04-03T00:59:39Z")

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We’ve had 60+ perfect prints and now we’re getting flash on our rafts. Anyone know what might be causing this?

 ![20190402_205628-1](https://us1.discourse-cdn.com/flex025/uploads/formlabs/original/2X/b/b5e6d689a2fb2729f1ad9558ad1234e71d032366.jpg)

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**Author:** ![JohnHue](https://avatars.discourse-cdn.com/v4/letter/j/48db29/32.png) [@JohnHue](https://forum.formlabs.com/u/JohnHue)\
**Post date:** [April 3, 2019, 7:55am UTC](https://forum.formlabs.com/t/flash-on-plate-around-raft/22892/2 "2019-04-03T07:55:48Z")

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This is typical when there is contamination on the optical path of the laser. Check the outer window of the tank, the optical window of the printer (both sides, shine a bright light at an angle to really see if it’s dirty or not). Those are the two easy steps and easy to correct (cleaning both sides the optical window of the printer is dead easy, contact Formlabs support if you’re unsure on how to proceed).

If there two steps don’t solve the issue then the contamination if further up the path, either the main mirror (unlikely in my experience) or directly on the galvo mirrors. Cleaning the galvo mirrors is a bit tricky, you should contact Formlabs support about that and they’ll send you a procedure and eventually cleaning supplies if needed.

Most of the time, if there is dust inside the printer (often visible on the inner side of the optical window), it’s likely a spot has made its way on one of the galvo mirrors and cleaning those usually solves the issue.

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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:** [April 17, 2019, 7:56am UTC](https://forum.formlabs.com/t/flash-on-plate-around-raft/22892/3 "2019-04-17T07:56:00Z")

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Closed on April 17, 2019, 7:56am UTC

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