Liquid cement, what can you do/

Hello everyone,
A couple of question about liquid cements. Specifically, Plastruct Plastic Weld and Flex-i-file plast-i-weld. Is there anything that can be done to keep it from “getting thick”? When first opened it is very thin and flows easily. As I continue to use it, it gets thicker and doesn’t flow as easily. Can it be from the type of brush I use or how it is stored. I keep it in the original bottle with the lid tight and at room temperature. Is there any way to thin it once it starts to thicken up?
Thanks & God Bless You,
Joe :+1: :+1:


The solvent evaporates and the thicker stuff goes thicker.
I switched to pure solvents many years ago, the only “drawback” is that it doesn’t fill
bad joints. Forces me to get the joints near “perfect” before fusing thme with the solvent.
The advantage is that there is very little cleanup afterwards, I don’t use putty for joints anymore.
The pure solvent will also evaporate after a while but the end result is an empty bottle without
any gooey stuff that needs to be cleaned out.
These solvents require very tight seals in the lids

You can thin it out by adding a bit of lacquer thinner to the bottle.

and some lacquer thinner will soften/solve polystyrene so they can be used to glue/weld
plastic parts …

Hello Robin / Heavy Arty,
Thanks for your help.
You say you use solvents. What else would/do you use beside the lacquer thinner?
Heavy Arty.
You say to use the lacquer thinner to thin the cement. How much would you use? That is, would it be a ratio of 10 to 1, 5 to 1 (cement to thinner)?
Thanks & God Bless,
Joe :+1: :+1:

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No idea. I just pour a bit in until it is as thin as I want it. Nothing scientific.

Laquer thinner: Available brands/names/mixtures will differ between where I can shop and where you can shop. I test the product with some scrap styrene (sprue runners, left over parts, packaging, old CD-cases et.c). If it glues I can use it.
Many acetone free nail polish removers can be used.
Laquer thinners from regular paint shops (test on scrap styrene). Automotive paint thinners may be too hot or too difficult to use in a safe manner, look at the precautions taken in car body paint booths …
If the product contains xylol, toluol or ethyl acetate it can be used. Ethyl acetate is the least harmful of those three, it is also a major component of some nail polish removers (significant other can’t complain about the smell if she uses it for her own fingernails …)
My absolute favourite is ethyl acetate.
I stumbled upon the laquer thinner when I tried to use it for aged Humbrol Enamels. It worked great but the paint brush left marks in the part I was painting. Had to find another thinner for my Humbrol tins but I had just become the happy owner of quarter gallon of super thin plastic cement.
Balsam turpentine is the good stuff for Humbrol tins in case you use Humbrol … not mineral based turpentine.
Ethyl Acetate (etac??)
Balsam Turpentine

Hey Guys,
Thanks so much for the additional information. It is very helpful indeed.
God Bless You,
Joe :+1: :+1:

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Hey Guys,
Just an after thought. Is there any particular type of brush you recommend for applying the cement? That is, natural as opposed to synthetic?
Thanks & God Bless You,
Joe :+1: :+1:

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I use small worn out brushes, sometimes synthetic, sometimes natural hair.
If the brush isn’t small enough or is very worn I cut off some of the bristles/hairs