How to avoid burn marks on 1/8" Birch (already used a masking tape)?

[jy1]

I was cutting 1/8" Birch with a medium-tack paper masking tape. The setting was Medium Basswood Playwood (150 Speed, Full Power, 0.13in Focus). There are some burn masks in some areas, please see the attached image. How can I avoid it? Thank you in advance for your help!

[Jules]

Be sure you use the edge of a scraper to rub the tape down really well when you apply it. The adhesive is activated by the rubbing, and if air gets underneath the masking, you’re going to get some staining.

[jy1]

Thank you, Jules! I will try rubbing the tape down a few more times.

[jamesdhatch]

@jy1

will try rubbing the tape down a few more times

Use a plastic card (like a credit card) or a printer’s brayer (from Michael’s or Amazon). That will get you enough pressure and they’re quick to use.

[jy1]

Thanks, James! I have used a long metal ruler to rub the masking tape a couple times, I will try rubbing it more.

[shop]

the other thing that can make that happen, even if you rub well, is either there being any dust on the wood to keep it from staying down or if the wood is a little “rough.” sometimes a really light sanding (literally 1-2 strokes across the whole area with a block sander) can smooth it out considerably for masking adhesion (just wipe the dust off).

[jy1]

Thanks for the tips!

[evansd2]

You might also be overpowering the cut.

I’d suggest dialing in your settings.

New material cut test method

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[brokendrum]

@jy1

avoid it

Overpower will almost always give you char, noticeable on the backside.

Something that creeps up on you are the fans. As they get dirty and air flow starts to decrease there is an increase in surface flaming. Eventually it gets out of hand enough to get noticed because it is charring the front side and even igniting the masking paper.

Does the beam focus point seem to be flaring more than normal? Time to clean the fan on the head and the exhaust.

[rgrannan]

Additionally, I have found that baby wipes and/or makeup remover wipes do a very good job of removing smoke damage from baltic birch. Rather than wiping, I press the wipe down hard on the wood, let it sit for a minute, peel it back and do it two or three more times. It doesn’t always get rid of ALL the damage, but it does really well especially on 3D engraves.