PabloPicasso
Well-Known Member
Is fairy washing up liquid a good improvised release agent for epoxy repairs? What else would you, or could, use?
What is the proper stuff called anyway?
What is the proper stuff called anyway?
Release agent
- Thread starter PabloPicasso
- Start date
macd
Well-Known Member
Oddly enough the proper stuff is called release agent, sometimes mould/mold release. Epoxy is generally more demanding of release agents than polyester, but for single-use applications this shouldn't be an issue for you. A good automotive wax polish (preferably carnauba-based), applied in several coats, will usually do the job. Avoid silicone-based polishes which can contaminate the cure. Proprietory relase agents are available as liquids, or spray-on, usually PVA-based.
Obviously a smooth release surface is paramount, whatever agent is used. Ordinary parcel tape works fine, but leaves tell-tale lines. There are also release films made for the purpose: any good epoxy supplier will stock them. Some are single-use, others can be re-used if you're not too fussy about the finish.
Washing-up liquid? I think not.
GrahamM376
Well-Known Member
Just enter "mould release wax" into ebay search, lots of hits. I also used some blue liquid from Scott Bader which is water soluble but can't remember the name.
lw395
Well-Known Member
Depending on what you are doing, a layer of ordinary polythene can be a good answer.
Since most epoxy needs to be coated/painted, a few light lines from parcel tape often won't matter.
Fairy liquid is quite good for cleaning uncured epoxy from brushes. So I'd guess it was pretty useless as a release agent....
Since most epoxy needs to be coated/painted, a few light lines from parcel tape often won't matter.
Fairy liquid is quite good for cleaning uncured epoxy from brushes. So I'd guess it was pretty useless as a release agent....
VicS
Well-Known Member
just to add that PVA mould release is polyvinyl alcohol.
It is not the same as PVA glue which is polyvinyl acatate
It is not the same as PVA glue which is polyvinyl acatate
PabloPicasso
Well-Known Member
are you suggesting parcel tape would not need an additional release agent, and that the epoxy wouldn't stick to its shiny surface?
macd
Well-Known Member
Clearly I don't know what he's suggesting, but I know that epoxy does release from uncoated parcel tape...but I've only tried it on relatively small and simple jobs. For anything with a large area (which, apart from anything else, invites damage in physically separating job from mould), I'd use release agent. A suitable wax polish would certainly do if nothing purpose-made was available. The larger and more complicated the shape of the job, the more reason to use a proprietory release agent.
Incidentally, someone suggested polythene as a release film. It works, sort of, but should only be used with solvent-free epoxies. For some reason it's hard to release when part-cured, but separates OK when fully cured. Polythene should on no account be used with -ester resins (unless you wan the final finish to be...er...polythene). Parcel tape is much to be preferred, not least 'cos you can stick it down.
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gus
Well-Known Member
melinex sheeting is great for making a flat shape in epoxy or polyester as is readily peels and does not adhere.
macd
Well-Known Member
+1
Works a treat on simple curves, too, against a former. No use for compound curves, of course.
Any good resin supplier should stock it (another reason for getting your laminating gear from them and not off a chandlery shelf).
steve jones
Member
Moulds will need to be made from non porous material. I've made loads of moulds from melamine faced MDF and parcel tape works well on cut edges but won't give a great finish. thin strips of thin styrene sheeting work well too. Any mould should use a release agent and washing up liquid is definitely not recommended. As Mac suggests I'd go to a proper supplier rather than a chandler. Alscot in Glasgow (allscotltd.co.uk) are really good and I think they will be able to supply small quantities of resin and release agent. They'd be able to recommend the right gear for your job too.
