Large Scale Central

M.E.K. Vs. Acetone as Polystyrene Welder ?

I have read that both will work, and that M.E.K. evaporates more slowly than Acetone. Anyone have first hand experience with both as a Polystyrene Welder? Looking for opinions. I have Acetone in stock, and am going out today and can grab a small can of MEK.

Also wondering if either will work (not dissolve) in my industrial syringe applicator. I have used Weldon 3 for Acrylics in it with no ill effects to the syringe. I don’t mind ruining one (they are cheap) but don’t want a hazmat spill on my work bench!

Jon,

I use MEK almost exclusively now. I still keep a bottle of hobby plastic cement on hand as it is helpful with pieces that need a little more holding power before the glue sets.

https://www.amazon.com/gp/aw/d/B00BNI6U52/ref=mp_s_a_1_12?ie=UTF8&qid=1511110737&sr=8-12&pi=AC_SX236_SY340_FMwebp_QL65&keywords=needle+bottle

I use a 2 or 3oz needle bottle and fill with MEK. Squeeze where you need it. MEK evaporates quickly so be for warned. I generally buy MEK by the quart as it is easier to fill the needle bottles. I have tried brush painting on the MEK but it evaporates too fast.

Craig

Thanks Craig. We had to go out anyway, so I grabbed a quart of M.E.K. at Home Depot - about $11 bucks with tax. I will try it in the syringe. If that melts I’ll pick up some needle bottles. Looks like the bottles are probably made from PET, Nylon or some other plastic which is impervious to MEK. I’ve used the syringes with various Eldon formulas for acrylics which are M.E.K. based so I’m hopeful it won’t melt.

My oldest son living in Tempe AZ won a Legoland auction a few years ago, 1 of 2 green silo displays (one of which continues on display). I contacted Legoland for some help on maintaining the building, MEK was the recommended product for gluing blocks together. The complex was relocated to the PAZ in NEPA.

LegoLand Mill complex.

Thanks Jon for bringing this up, and thanks Craig & Bob for your answers. I’ve been using Scigrip / Weldon 3 & 4 for my acrylic models, but it’s expensive to buy and ship. Does it work on acrylic as well as polystyrene? If so, I’d like to give MEK a whirl.

Poly I have not experimented with; will have to research composition Lego block.

I have used both for all sorts of plastics. MEK was the solvent (note the word) supplied by the company I did professional modeling for in the late 1980s. I have successfully used MEK on styrene (as supplied by Evergreen and Plastruct), ABS plastic (Plastruct), and Acrylic (Home Depot and many scrap plastics if have found). MEK works better in my opinion, although I have found some plastics that neither will work on (ie the plastic bases of the LED votiv candles in particular). I have used both all of the application methods - syringe, rubber bulb bottle and brush - and each has it’s strong points. I have found that the Acrylics are the slowest to ‘set’ and I usually clamp them for at least 30 minutes to insure a strong joint before moving on. The tightness and roughness of the surfaces of the joint also make a big difference in setting time. For poor fit up joints I am becoming a fan of ‘thick ACC’.

Cliff,

Try MEK, you won’t look back. I’ve used it to weld different types of plastic together as well as similar plastics.

The needle bottles sometimes clog up, but a quick flame to the end burns off the clog and it keeps flowing. I still keep a bottle of Testors glue around but I use it maybe 1% of the time. Its a little thicker than MEK so if I need some tactless to hold a part I use Testors. I also try to glue up as much as possible on glass plates.

This website post , if accurate, lists all different types of plastics and which solvents work and which do not. MEK is about as universal as it gets according to the post.

My syringe survived the initial test with no ill effects. I like the needle bottles as the look easier to control.

Please tell us which website, sounds interesting. Bob.

Click on the words website post in my post or this one. It is a hot link.

I’ve been gluing together different plastics for 37 years now (!) at my job at TAP Plastics. I’ve seen a lot of really useful solvents disappear here in California as the VOC (Volatile Organic Compound) laws make them illegal. MEK has been the latest added to the list. We used to sell pure MEK by the Gallon and 5 Gallon container, now my customers have to go to Nevada to acquire large quantities of it.

We use MEK at TAP Plastics to solvent weld together ABS and High Impact Styrene (Polystyrene). Nothing works better. If you need some body to the glue, I recommend using SCIGrip Weld-On 16 . The Weld-On 16 contains MEK along with other solvents along with Acrylic Monomer to thicken it. Here is the SDS… TAP Plastics also sells SCIgrip Weld-on 2354 for ABS and Styrene. It is mostly MEK and it is what we have to use in the shop now… Here is the SDS Of course, I use MEK at home.(http://www.largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-smile.gif)

For the expanded PVC (Sintra, Komatex or Celtec) and other PVC sheets we use Weld-On 2007.It is a solvent only formula with no thickeners added so it flows really well.

For Acrylic Plastic we use Weld-On #4, #3 and the TAP Acrylic Cement. #4 is a little slower in evaporation and thus has more time to melt the acrylic and make a strong bond. We use this the most, especially on aquariums and thicker sheets. The TAP brand and the #3 are the same product but we are able to sell it at a lower price since it carries our name. These are the Applicators we use to apply these water thin solvents…

Jon posted this link…" http://nerfhaven.com/forums/topic/18527-intro-to-solvent-welding-plastic/ " and in general it is correct. I would never use MEK or Acetone to glue Acrylic… I’ve mixed up bottles in the past in our shop and I can tell you accidentally using MEK on acrylic doesn’t work. The joints fail quite easily… Also, I’ve never found a solvent that will bond HDPE, UHMW, LDPE, Polypropylene or Delrin. Heck, the solvent applicators mentioned earlier are made of solvent resistant polyethylene! I also found it interesting that he says Methylene Dichloride is banned in Europe while Ethylene Dichloride is not… The opposite occurs here.

Russ Miller

Past BAGRS President

NGRC 2016 Chairman

TAP Plastics Manager

Big thanks Russell. I’ve been using SG #4, but was planning on trying to glue acrylic shingles with MEK. So thanks for the averted mess! I’ll get more #4.

Cliff

I have been using Weld-On 16 primarily because I’ve always had difficulty finding MEK in anything less than a gallon can (and even that was difficult). I was at my local Ace Hardware and I found “Painter’s Solvent,” which says on the can that it replaces MEK. Has anyone ever seen or tried it before? Thoughts?

Sadly, MEK has been banned here in the People’s Republic of Kalifornia. I bought a quart can shortly before they stopped selling it. If I had known, I would have bought a gallon. I haven’t run out yet but I will eventually so I too am curious as to whether there is a decent substitute. I don’t think acetone works very well.

I have used MEK, and acetone, but I also use “Lacqure Thinner”, in fact I use it more than anything else, but it contains some of both of the others, I’ve been told. We can easily get all of them here in Ottawa…Home Depot, and Crappy Tire carry them.

Fred Mills

Thank you Russ for that detailed post. Very helpful info there. I do a lot of work with acrylics and expanded PVC board in my sign shop job. I use SciGrip 4 for acrylic and it works great for me. For foamed PVC to Foamed PVC I have used the self priming PVC pipe adhesive you can get at the big box stores with good results. I use Weldon 16 at home for lots of modeling uses with generally good results. Last night I tried bonding Foamed PVC board to Styrene (A coupler mounting pad to a Delton Classic frame) with MEK and the joint failed after 10 hours or so dry time, Today I re-joined it with Weldon-16 which I have used for the same job before with great results. I also leaned not to over apply the MEK. I was using it to repair a broken truck mount with a PVC pad and a T-Nut from above. I nearly melted through the frame!

Ray Dunakin said:

Sadly, MEK has been banned here in the People’s Republic of Kalifornia. I bought a quart can shortly before they stopped selling it. If I had known, I would have bought a gallon. I haven’t run out yet but I will eventually so I too am curious as to whether there is a decent substitute. I don’t think acetone works very well.

Why not LOAD UP Ray when you visit a state that has not banned it(http://largescalecentral.com/externals/tinymce/plugins/emoticons/img/smiley-tongue-out.gif)

Seems this is very good for acrylics…easy to apply…

https://www.tapplastics.com/product/repair_products/plastic_adhesives/tap_acrylic_cement/130

FYI for Californians, MEK readily available in NV, just a quick trip over the boarder and available at most paint and hardware stores. Minimum size a pint. Best thing is that you can enjoy a day of skiing or gambling while making this purchase.