I’ve read the [very informative] chipboard puzzle posts and started on my own journey using the 0.1" chipboard from Dick Blick with photo paper and a light sealer coat on top. It calipered at 0.13". I’ve had two attempts so far. For my first I used 180/100 and it didn’t make it all the way through. It was close…on one corner it made it through all the way…for the rest of it there was little pin-prick marks on the back but that was it. The front had some char as well which is less than desirable.
So…I tried again with the same setup but went for full power (basic), speed 190. The good news…it cut marvelously. Bad news…when I tried to pick up the pieces my hands quickly became covered in soot. Eek! That’s not a particularly good trait to have in a puzzle, so I need to reconsider.
I need some help! I’m a “laser noob” so I don’t have a good idea of how changing the settings will eliminate my issues…I need a full cut, less cremation, and minimal charring (and I DEFINITELY don’t want to mask it!) Do I need to stay at 100 power but lower the speed? Full power but faster? Should I go faster at lower power but do two passes? Should I laser face-down? If so, what’s a good way to get my puzzle SVG image to correctly overlay my material? Eek!
Toss the pieces in a large ziploc bag with some salt and shake, shake, shake…shake, shake, shake… shake your booty! 
That’s a good approach.
Really…salt?! How fascinating! Is there some chemical reaction involved or is it simply abrasion?
I was wondering if there was some way to remove it. I started to wipe each piece with a damp paper towel, but the puzzle had 320 pieces, and while I’m not against repetitive tasks, that was definitely going to make me lose my marbles…
Abrasion…pure mechanical removal. (I’ve never done it, but that’s what our puzzle selling expert does.) 
I’ve done hundreds of tests on chipboard and I don’t think you’ll be able to cut without some charring, since it’s basically several plies of paper. I’ve found that cutting at power 100 and making multiple passes creates less char and a tighter kerf. For example, the chipboard I use is .08” and then .09” with the 10 mil photo paper. It will cut at 180/Full (on a pro) but it chars more and leaves a bigger kerf. If I do 2 passes at 260/100, it takes the same amount of time but a smaller kerf and less char.
I use a finishing varnish before cutting. If you’re using a photo paper, it needs to be a spray finish (lower water content - the liquid varnish will cause the ink to run when you spread it). If you’re using a canvas or rag-type paper, you could use a liquid varnish.
I cut image side up for a few reasons also. One, I feel that it makes a tighter fitting piece. Image side down will give you a smaller apparent kerf when looking at the puzzle, but it removes more material from the guts (middle portion). Two, some soot is inevitable - if you cut image side up, you can wipe down the entire face of the puzzle while it’s laying in the laser bed, after cutting, with a very, very slightly damp towel. Three, if you have pieces that don’t cut all of the way through, you can finish the cut with an exacto knife without cutting the face of the puzzle - it looks more consistent because the laser has already cut through the face.
Salt is THE way to clean the sooty edges. I think this is the main reason no one really offers laser cut chipboard puzzles (the laser cutting puzzle companies all do wood) - because the pieces do have to be cleaned and it’s an extra step in the process. I’ve used different types of salt and have concluded that the larger grain salts work just as effectively in cleaning the edges/nooks and crannies as fine grain salt, but leave way less salt powder residue on the pieces. I buy pool salt because it’s easy to find and you can buy 30-40 lb bags of it. I cut in about 250-piece segments of a puzzle (2 jobs) and clean the 250 at one time. I put a cup of salt into a Tupperware container and just roll it around for about 30 seconds.
Then, I have an IKEA kitchen utensil holder (of all things lol) that I dump the pieces and salt into from the Tupperware container. It has holes all down the side and button and the salt drains out into an aluminum pan. I have also laser cut a Tupperware lid with holes everywhere, that I can swap lids and just turn upside down and let the salt run out.
Wow…thank you SO much for this insightful post. As a result of your previous (and equally insightful) posts I had gotten MOST of the way there, but was missing a few of the key details. This will definitely help me and no doubt help many others too!
My husband is the photographer and over the years has amassed countless shots of Philadelphia…lots of “real life” ones in addition to the iconic historic buildings of which everyone is familiar. My goal is to bring his images to life as puzzles. I don’t know if I’ll ever get around to making it a business but even if I did it wouldn’t be anything on a large scale. I don’t mind a bit of extra work but definitely appreciate anything that optimizes one’s time!
Oh and yes, Ikea is a simply brilliant source for all kinds of unexpected objects! Half the time I walk around the store with at least one thing that I plan to use in a matter for which it was never intended.
Thanks for being so detailed… i was about to post a SOS thread but I’ll try your method first. I’ve been burning my puzzles as well. Theres too much burn on the sides of the puzzle pieces… I’ve finally been able to make a decent one, but it still has too much of a gap. Will definitely try a faster and less power with multiple passes for a tighter fit. Thanks
Chipboard can also vary a lot in density from manufacturer to manufacturer. My old paper supplier switched manufactures on me, and besides its tendency to warp, it was just really tough to cut (it’s fairly tough to cut normally anyways but this was really tough). It felt heavy to me, so I compared it to an old piece that I had (both same thickness), the new stuff was about 25% heavier.
I was wondering if you could tell me the type of finishing varnish that you use. I have looked at a few and can’t figure out which ones would be most safe for photos. I have an acrylic sealer with gloss finish as well as a polycrylic but it is water based so wasn’t sure I should use it. If you have a specific one you use or a brand you like I would really appreciate it! Thank you!!
If you search through the forum for JB’s puzzle posts, he shares a lot of that info as it evolved over time. I’m sure he’ll eventually pop by, but just in case it takes awhile.
I use pool salt for chipboard and anything else that burns in a bussing tub I got from Sam’s Club.
any dishpan would do. I just happen to have bussing tubs. you can use them as “drawers” by making a simple cabinet and they slide right in and can be removed to transport the contents to where you need to work.
The biggest thing is to experiment. The actual varnishes are almost always fine. Most finishes that I’ve experimented with that are spray based are fine actually.
I used Varathane triple thick spray polyurethane for the puzzles I did here:
I doubt the brand really matters.