formaldehyde greater than or equal to 1, preferably 1 :0.2 to 1:0.9, preferably 1:0.2 to 1:0.8, and particularly preferably 1:0.3 to 1:0.7. 

6. The method according to claim 1, wherein the acid catalyst for the production of the reaction product from formaldehyde and furfuryl alcohol is an acid with a pKa value of 2.7 to 6, preferably with a pKa value of 3 to 5, and particularly preferably lactic acid or adipic acid, as well as combinations thereof. 

7. The method according to claim 1, wherein the resin component contains O to 25% by weight, preferably 1 to 20% by weight, and in particular preferably 3 to 15% by weight reaction products of formaldehyde and urea. 

8. ( canceled) 

9. The method according to claim 1, wherein the overall amount of water in the resin component is at most 40% by weight, preferably at most 35% by weight, and particularly preferably at most 30% by weight. 

10. The method according to claim 1, wherein the resin component additionally comprises an organic solvent that is not furfuryl alcohol with 1 to 25 carbon atoms, preferably alcohols, in particular ethanol, wherein the amount of organic solvent does not exceed an amount of 30% by weight, preferably an amount of 25% by weight, and par› ticularly preferably an amount of 20% by weight. 

11. The method according to claim 1, wherein the resin component has a viscosity (DIN EN ISO 2555, Brookfield, 25° C.) of 2 mPas to 70 mPas, preferably 5 mPas to 60 mPas and particularly preferably 5 mPas to 50 mPas at 25° C. 

12. The method according to claim 1, wherein the resin component at 20° C. has a surface tension from 10 mN/m to 70 mN/m, preferably from 15 mN/m to 60 mN/m, particu› larly preferably from 15 mN/m to 55 mN/m and especially preferably from 20 mN/m to 50 mN/m, determined by the Wilhelmy plate method with a Kriiss Kl 00 force tensiometer at 20° C. 

13. The method according to claim 1, wherein the amount of the resin component is between 0.1% by weight and 5.3% by weight, preferably between 0.3% by weight and 4.3% by weight, and particularly preferably between 0.5% and 3.1 % by weight, relative to the refractory basic mold material, or respectively between 0.1 % by weight and 5% by weight, preferably between 0.3% by weight and 4% by weight, and particularly preferably between 0.5% by weight and 3% by weight, relative to the mold material mixture. 

14. The method according to claim 1, wherein the acid used for curing the resin component has a pKa value at 25° C. of less than 4, preferably with a pKa value less than or equal to 3.9, preferably with a pKa value less than 3, and particularly preferably within a pKa value less than 1.5. 

15. The method according to claim 1, wherein the acid component of the binder is para-toluenesulfonic acid, sul› furic acid, or lactic acid, or a mixture thereof. 

16. The method according to claim 1, wherein the amount of the acid is between 0.1 % by weight to 3.1 % by weight, preferably between 0.1 % by weight and 2.6% by weight, and particularly preferably between 0.1 % and 2.1 % by weight acid, relative to the refractory basic mold material, or respectively between 0.1% by weight to 3% by weight, preferably between 0.1 % by weight and 2.5% by weight, and particularly preferably between 0.1 % by weight and 2% by weight, relative to the mold material mixture. 

17. The method according to claim 1, wherein the refrac› tory basic mold material comprises one or more constituents 

of the group cons1stmg of quartz sand, zirconium sand, chrome ore sand, olivine, vermiculite, bauxite, fireclay, glass pearls, glass granules, aluminum silicate microspheres and mixtures thereof. 

18. The method according to claim 1, wherein the refrac› tory basic mold material has an average particle diameter of 30 µm to 500 µm, preferably between 40 µm and 400 µm, and particularly preferably between 50 µm and 250 µm. 

19. The method according to claim 1, wherein the refrac› tory basic mold material is used at more than 80% by weight, preferably more than 90% by weight, and particularly pref› erably more than 95% by weight relative to the mold material mixture. 

20. The method according to claim 1, wherein the acid is added to the refractory basic mold material discharged layerwise, wherein the mixture is produced from acid and basic mold material preferably at 10° C. to 45° C., and the layer thickness of the mixture consisting of acid and basic mold material is 0.03 mm to 3 mm, preferably 0.03 mm to 1.5 mm, before selected regions of the mixture consisting of acid and basic mold material are selectively printed with the resin component. 

21. The method according to claim 1, wherein the tem› perature of the printhead is between 20° C. to 80° C. 

22. The method according to claim 1, further comprising the following steps: 

i) after termination of layerwise construction, curing the body in an oven or by microwaving, and then 

ii) removing the unprinted mixture consisting of the acid or resin component and basic molding material from the at least partially cured casting mold. 

23. The method according to claim 1, wherein the print› head has a plurality of nozzles, and the nozzles are prefer› ably selectively controllable individually, wherein the print› head is in particular a drop-on-demand printhead with a bubble jet or piezo system. 

24. The method according to claim 1, wherein the print› head is movably controlled by a computer, at least in one plane, and the nozzles apply at least one component layer› wise, and/or the printhead is heatable. 

25. A mold or core producible according to the method of claim 1 for metal casting, in particular iron, steel, copper or aluminum casting. 

26. The method of claim 1, wherein the resin component comprising a furane resin is a reaction product from at least an aldehyde compound and furfuryl alcohol, and compounds containing nitrogen and/or phenol compounds, wherein the nitrogen content of the resin component is less than 5% by weight, and wherein the resin component comprises more than 5% by weight and less than 50% by weight monomer furfuryl alcohol, relative to the resin component. 

27. The method according to claim 26, wherein: 

the compounds containing nitrogen include urea, and/or 

the amount of the compounds containing nitrogen is chosen such that the overall amount of nitrogen in the resin component is less than 5% by weight, preferably less than 3.5% by weight and particularly preferably less than 2% by weight. 

28. The method according to claim 5, wherein the furane resin is a reaction product from furfuryl alcohol and form› aldehyde, as well as compounds containing nitrogen, such as preferably urea, preferably with a molar ratio of furfuryl 

