Odd question.....

[yamaha_george]

I have been asked if I have ever used UP foam (that self expanding stuff builders use round window & door frames & cavities in walls filler) for making a "buck" or former for making fibre glass moulds etc.

I have not but just curious if any of you have ?

[haro504]

ive thought about it before theres a paint on latex mold stuff that you keep painting on in layers and as it dries gets thicker and after you peal it off and you have a latex mold so i thought about using that first and then spraying on the expansion foam because it sticks so well and hardens, then peal it off and i would have a firm flexable mold. was thinking of this for an upper fairing i havent tried it but seem solid as a theory

[yamaha_george]

ive thought about it before theres a paint on latex mold stuff that you keep painting on in layers and as it dries gets thicker and after you peal it off and you have a latex mold so i thought about using that first and then spraying on the expansion foam because it sticks so well and hardens, then peal it off and i would have a firm flexable mold. was thinking of this for an upper fairing i havent tried it but seem solid as a theory

H,
I have been told there are two types of cannned foam Hi & lo expanding. Hich expanding can actuallly be so powerful as to break the glass when used round window frames. So we need to watch it does not break the original!

the second is that this can really generate HEAT to the point of catching fire if sprayed in large quantities , so it needs to be applied in layers.

What is this latex stuff you were saying about ????

[haro504]

i cant remember what it was called i found it online one day its supposed to be at most craft stores but you just keep painting it on to an item and it builds up till its thickenough to peal off. your supposed to get pretty good detail with it though i though of a foam as a backer for big peices

[haro504]

here some for an idea theres a bunch of diferent kinds with different qualities some take heat better
http://cgi.ebay.com/500ml-Thickened-LIQ ... 3a5aa5693b

[yamaha_george]

i cant remember what it was called i found it online one day its supposed to be at most craft stores but you just keep painting it on to an item and it builds up till its thickenough to peal off. your supposed to get pretty good detail with it though i though of a foam as a backer for big peices

Ok I will try Google for it and the PU foam back to keep it stiff as the latex I know from theatre stuff is just too floppy!!
now now boys keep the mind clean LoL

[yamaha_george]

here some for an idea theres a bunch of diferent kinds with different qualities some take heat better
http://cgi.ebay.com/500ml-Thickened-LIQ ... 3a5aa5693b

Thanks Harro for the link

Thank you to all who replied.
 what I have found out from you and others.

High & Low density foam can exert a lot of force so the base formers need to
be VERY strong

There should be "drain" holes so that excess pressure can escape  (like plumes
in casting)

work in a WELL ventilated area wear a mask as both gases & particles do not
play nice with the human body.

the canned stuff is not as good as two part mixes

 2 part mixes have to be accurate in measurement and well mixed or they are
play the fool.

Boat yards can be persuaded to do your foaming for you when they are on "a
run"

 expect that the  size is not very accurate as the material alters dimensions
with heat & humidity.

DO NOT spray vast quantities at once do it in layers as the material generates
heat when curing (over days) & has been know to self combust!!!

Well now you know as much as I do
Thanks to all who passed on their knowledge.