Acrylic crack

  • We are currently upgrading MFK. thanks! -neo
Honestly if its a large enough crack you might need to cut a scrap of acrylic to patch over it on the inside. Stress can weaken it and although weld-on will seal it and chemically re-bond it, its still going to have strain in that area. BTW I make my own weld-on by disolving acrylic in acetone until its the viscosity I like. takes time but saves money, no need to wait for shipping and you can get the exact viscosity you want.
 
Weld-on is different then acetone (better) TAP plastics carries it if you are still looking for it. As mentioned depending on the placement of the crack a extra piece glued on to it would help strengthen it. if you do this make sure the new piece is cast acrylic otherwise you can have problems. If it's along a joint or something and you can't add a piece you can use some weldon 16 after the 4 cures.
 
What does weld on have in it that makes it desirable over acetone-dissolved acrylic? I'm new to this still so I could use the info. I used my concoction to seal and baffle my sump. Nothing load bearing but if I made a mistake now would be a good time for me to fix it
 
Acetone can cause blushing which weldon will not in most cases, I don't think acetone forms as strong of a bond because it completely evaporates quickly. Weldon 4 (Methyl Methacrylate Monomer, Trichloroethylene, and Methylene Chloride (dichloromethane)) forms a quick bond, but then takes a few days to fully develop it's full strength.

Where I work we use mostly Weldon 3 which cures faster which works great for display cases and original builds. 4 is nice for repairs because it can penetrate deeper before curing.

And for a little extra knowledge most large acrylic tank manufactures use a two part weldon 44
 
When comparing to acetone, are you talking about applying pure acetone to pieces you want to join or a slurry made by dissolving acrylic shards into acetone to make a more viscous slurry?

Either way thanks for the info

Sent from the mars rover
 
I was talking about pure acetone. I haven't used acetone for gluing since I have access to Weldon so I can't comment too much on it. In your slurry though the only chemical is still just acetone. The acrylic would probably slow the cure rate and add filler but still could cause blushing. Weldon16 is similar to this but with the chemicals from Weldon 4.

Also using 3 or 4 can be better since it is water then and can penetrate to the bottom of the crack.
 
I see. So far this slurry has worked but its just for capping things off and adding baffles to my sump. No blemishing that i can see but its an ugly mess anyhow since it was my first attempt and its going to be hidden so I wasnt worried about it.

If i did work on my tank Id probably go with weld on

Sent from the mars rover
 
http://www.mcmaster.com/#weld-on-adhesives/=jv6t4x

I'm in Cali and ordered the 4oz can of Weldon #4 a few weeks ago and it arrived with no fuss. The can does say "low VOC" so I think it's the newest one that is CA approved. They ship same day and you can choose overnight shipping.

Also, if it's truly just a crack the pieces should mate up better than any normal surface prep, but you have to drain and let the tank dry. I would put painters tape on the outside and lay the tank on it's side or whatever orientation so that the weldon can wick down into it but not drip out the other side.
 
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